1Config(3pm)            Perl Programmers Reference Guide            Config(3pm)
2
3
4

NAME

6       Config - access Perl configuration information
7

SYNOPSIS

9           use Config;
10           if ($Config{usethreads}) {
11               print "has thread support\n"
12           }
13
14           use Config qw(myconfig config_sh config_vars config_re);
15
16           print myconfig();
17
18           print config_sh();
19
20           print config_re();
21
22           config_vars(qw(osname archname));
23

DESCRIPTION

25       The Config module contains all the information that was available to
26       the "Configure" program at Perl build time (over 900 values).
27
28       Shell variables from the config.sh file (written by Configure) are
29       stored in the readonly-variable %Config, indexed by their names.
30
31       Values stored in config.sh as 'undef' are returned as undefined values.
32       The perl "exists" function can be used to check if a named variable
33       exists.
34
35       For a description of the variables, please have a look at the Glossary
36       file, as written in the Porting folder, or use the url:
37       https://github.com/Perl/perl5/blob/blead/Porting/Glossary
38
39       myconfig()
40           Returns a textual summary of the major perl configuration values.
41           See also "-V" in "Command Switches" in perlrun.
42
43       config_sh()
44           Returns the entire perl configuration information in the form of
45           the original config.sh shell variable assignment script.
46
47       config_re($regex)
48           Like config_sh() but returns, as a list, only the config entries
49           who's names match the $regex.
50
51       config_vars(@names)
52           Prints to STDOUT the values of the named configuration variable.
53           Each is printed on a separate line in the form:
54
55             name='value';
56
57           Names which are unknown are output as "name='UNKNOWN';".  See also
58           "-V:name" in "Command Switches" in perlrun.
59
60       bincompat_options()
61           Returns a list of C pre-processor options used when compiling this
62           perl binary, which affect its binary compatibility with extensions.
63           "bincompat_options()" and "non_bincompat_options()" are shown
64           together in the output of "perl -V" as Compile-time options.
65
66       non_bincompat_options()
67           Returns a list of C pre-processor options used when compiling this
68           perl binary, which do not affect binary compatibility with
69           extensions.
70
71       compile_date()
72           Returns the compile date (as a string), equivalent to what is shown
73           by "perl -V"
74
75       local_patches()
76           Returns a list of the names of locally applied patches, equivalent
77           to what is shown by "perl -V".
78
79       header_files()
80           Returns a list of the header files that should be used as
81           dependencies for XS code, for this version of Perl on this
82           platform.
83

EXAMPLE

85       Here's a more sophisticated example of using %Config:
86
87           use Config;
88           use strict;
89
90           my %sig_num;
91           my @sig_name;
92           unless($Config{sig_name} && $Config{sig_num}) {
93               die "No sigs?";
94           } else {
95               my @names = split ' ', $Config{sig_name};
96               @sig_num{@names} = split ' ', $Config{sig_num};
97               foreach (@names) {
98                   $sig_name[$sig_num{$_}] ||= $_;
99               }
100           }
101
102           print "signal #17 = $sig_name[17]\n";
103           if ($sig_num{ALRM}) {
104               print "SIGALRM is $sig_num{ALRM}\n";
105           }
106

WARNING

108       Because this information is not stored within the perl executable
109       itself it is possible (but unlikely) that the information does not
110       relate to the actual perl binary which is being used to access it.
111
112       The Config module is installed into the architecture and version
113       specific library directory ($Config{installarchlib}) and it checks the
114       perl version number when loaded.
115
116       The values stored in config.sh may be either single-quoted or double-
117       quoted. Double-quoted strings are handy for those cases where you need
118       to include escape sequences in the strings. To avoid runtime variable
119       interpolation, any "$" and "@" characters are replaced by "\$" and
120       "\@", respectively. This isn't foolproof, of course, so don't embed
121       "\$" or "\@" in double-quoted strings unless you're willing to deal
122       with the consequences. (The slashes will end up escaped and the "$" or
123       "@" will trigger variable interpolation)
124

GLOSSARY

126       Most "Config" variables are determined by the "Configure" script on
127       platforms supported by it (which is most UNIX platforms).  Some
128       platforms have custom-made "Config" variables, and may thus not have
129       some of the variables described below, or may have extraneous variables
130       specific to that particular port.  See the port specific documentation
131       in such cases.
132
133   _
134       "_a"
135           From Unix.U:
136
137           This variable defines the extension used for ordinary library
138           files.  For unix, it is .a.  The . is included.  Other possible
139           values include .lib.
140
141       "_exe"
142           From Unix.U:
143
144           This variable defines the extension used for executable files.
145           "DJGPP", Cygwin and OS/2 use .exe.  Stratus "VOS" uses .pm.  On
146           operating systems which do not require a specific extension for
147           executable files, this variable is empty.
148
149       "_o"
150           From Unix.U:
151
152           This variable defines the extension used for object files.  For
153           unix, it is .o.  The . is included.  Other possible values include
154           .obj.
155
156   a
157       "afs"
158           From afs.U:
159
160           This variable is set to "true" if "AFS" (Andrew File System) is
161           used on the system, "false" otherwise.  It is possible to override
162           this with a hint value or command line option, but you'd better
163           know what you are doing.
164
165       "afsroot"
166           From afs.U:
167
168           This variable is by default set to /afs. In the unlikely case this
169           is not the correct root, it is possible to override this with a
170           hint value or command line option.  This will be used in subsequent
171           tests for AFSness in the configure and test process.
172
173       "alignbytes"
174           From alignbytes.U:
175
176           This variable holds the number of bytes required to align a
177           double-- or a long double when applicable. Usual values are 2, 4
178           and 8.  The default is eight, for safety.
179
180       "aphostname"
181           From d_gethname.U:
182
183           This variable contains the command which can be used to compute the
184           host name. The command is fully qualified by its absolute path, to
185           make it safe when used by a process with super-user privileges.
186
187       "api_revision"
188           From patchlevel.U:
189
190           The three variables, api_revision, api_version, and api_subversion,
191           specify the version of the oldest perl binary compatible with the
192           present perl.  In a full version string such as 5.6.1, api_revision
193           is the 5.  Prior to 5.5.640, the format was a floating point
194           number, like 5.00563.
195
196           perl.c:incpush() and lib/lib.pm will automatically search in
197           $sitelib/.. for older directories back to the limit specified by
198           these api_ variables.  This is only useful if you have a perl
199           library directory tree structured like the default one.  See
200           "INSTALL" for how this works.  The versioned site_perl directory
201           was introduced in 5.005, so that is the lowest possible value.  The
202           version list appropriate for the current system is determined in
203           inc_version_list.U.
204
205           "XXX" To do:  Since compatibility can depend on compile time
206           options (such as bincompat, longlong, etc.) it should (perhaps) be
207           set by Configure, but currently it isn't.  Currently, we read a
208           hard-wired value from patchlevel.h.  Perhaps what we ought to do is
209           take the hard-wired value from patchlevel.h but then modify it if
210           the current Configure options warrant.  patchlevel.h then would use
211           an #ifdef guard.
212
213       "api_subversion"
214           From patchlevel.U:
215
216           The three variables, api_revision, api_version, and api_subversion,
217           specify the version of the oldest perl binary compatible with the
218           present perl.  In a full version string such as 5.6.1,
219           api_subversion is the 1.  See api_revision for full details.
220
221       "api_version"
222           From patchlevel.U:
223
224           The three variables, api_revision, api_version, and api_subversion,
225           specify the version of the oldest perl binary compatible with the
226           present perl.  In a full version string such as 5.6.1, api_version
227           is the 6.  See api_revision for full details.  As a special case,
228           5.5.0 is rendered in the old-style as 5.005.  (In the 5.005_0x
229           maintenance series, this was the only versioned directory in
230           $sitelib.)
231
232       "api_versionstring"
233           From patchlevel.U:
234
235           This variable combines api_revision, api_version, and
236           api_subversion in a format such as 5.6.1 (or 5_6_1) suitable for
237           use as a directory name.  This is filesystem dependent.
238
239       "ar"
240           From Loc.U:
241
242           This variable is used internally by Configure to determine the full
243           pathname (if any) of the ar program.  After Configure runs, the
244           value is reset to a plain "ar" and is not useful.
245
246       "archlib"
247           From archlib.U:
248
249           This variable holds the name of the directory in which the user
250           wants to put architecture-dependent public library files for
251           $package.  It is most often a local directory such as
252           /usr/local/lib.  Programs using this variable must be prepared to
253           deal with filename expansion.
254
255       "archlibexp"
256           From archlib.U:
257
258           This variable is the same as the archlib variable, but is filename
259           expanded at configuration time, for convenient use.
260
261       "archname"
262           From archname.U:
263
264           This variable is a short name to characterize the current
265           architecture.  It is used mainly to construct the default archlib.
266
267       "archname64"
268           From use64bits.U:
269
270           This variable is used for the 64-bitness part of $archname.
271
272       "archobjs"
273           From Unix.U:
274
275           This variable defines any additional objects that must be linked in
276           with the program on this architecture.  On unix, it is usually
277           empty.  It is typically used to include emulations of unix calls or
278           other facilities.  For perl on OS/2, for example, this would
279           include os2/os2.obj.
280
281       "asctime_r_proto"
282           From d_asctime_r.U:
283
284           This variable encodes the prototype of asctime_r.  It is zero if
285           d_asctime_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
286           of reentr.h if d_asctime_r is defined.
287
288       "awk"
289           From Loc.U:
290
291           This variable is used internally by Configure to determine the full
292           pathname (if any) of the awk program.  After Configure runs, the
293           value is reset to a plain "awk" and is not useful.
294
295   b
296       "baserev"
297           From baserev.U:
298
299           The base revision level of this package, from the .package file.
300
301       "bash"
302           From Loc.U:
303
304           This variable is defined but not used by Configure.  The value is
305           the empty string and is not useful.
306
307       "bin"
308           From bin.U:
309
310           This variable holds the name of the directory in which the user
311           wants to put publicly executable images for the package in
312           question.  It is most often a local directory such as
313           /usr/local/bin. Programs using this variable must be prepared to
314           deal with ~name substitution.
315
316       "bin_ELF"
317           From dlsrc.U:
318
319           This variable saves the result from configure if generated binaries
320           are in "ELF" format. Only set to defined when the test has actually
321           been performed, and the result was positive.
322
323       "binexp"
324           From bin.U:
325
326           This is the same as the bin variable, but is filename expanded at
327           configuration time, for use in your makefiles.
328
329       "bison"
330           From Loc.U:
331
332           This variable is used internally by Configure to determine the full
333           pathname (if any) of the bison program.  After Configure runs, the
334           value is reset to a plain "bison" and is not useful.
335
336       "byacc"
337           From Loc.U:
338
339           This variable is used internally by Configure to determine the full
340           pathname (if any) of the byacc program.  After Configure runs, the
341           value is reset to a plain "byacc" and is not useful.
342
343       "byteorder"
344           From byteorder.U:
345
346           This variable holds the byte order in a "UV". In the following,
347           larger digits indicate more significance.  The variable byteorder
348           is either 4321 on a big-endian machine, or 1234 on a little-endian,
349           or 87654321 on a Cray ... or 3412 with weird order !
350
351   c
352       "c" From n.U:
353
354           This variable contains the \c string if that is what causes the
355           echo command to suppress newline.  Otherwise it is null.  Correct
356           usage is $echo $n "prompt for a question: $c".
357
358       "castflags"
359           From d_castneg.U:
360
361           This variable contains a flag that precise difficulties the
362           compiler has casting odd floating values to unsigned long: 0 = ok 1
363           = couldn't cast < 0 2 = couldn't cast >= 0x80000000 4 = couldn't
364           cast in argument expression list
365
366       "cat"
367           From Loc.U:
368
369           This variable is used internally by Configure to determine the full
370           pathname (if any) of the cat program.  After Configure runs, the
371           value is reset to a plain "cat" and is not useful.
372
373       "cc"
374           From cc.U:
375
376           This variable holds the name of a command to execute a C compiler
377           which can resolve multiple global references that happen to have
378           the same name.  Usual values are "cc" and "gcc".  Fervent "ANSI"
379           compilers may be called "c89".  "AIX" has xlc.
380
381       "cccdlflags"
382           From dlsrc.U:
383
384           This variable contains any special flags that might need to be
385           passed with "cc -c" to compile modules to be used to create a
386           shared library that will be used for dynamic loading.  For hpux,
387           this should be +z.  It is up to the makefile to use it.
388
389       "ccdlflags"
390           From dlsrc.U:
391
392           This variable contains any special flags that might need to be
393           passed to cc to link with a shared library for dynamic loading.  It
394           is up to the makefile to use it.  For sunos 4.1, it should be
395           empty.
396
397       "ccflags"
398           From ccflags.U:
399
400           This variable contains any additional C compiler flags desired by
401           the user.  It is up to the Makefile to use this.
402
403       "ccflags_uselargefiles"
404           From uselfs.U:
405
406           This variable contains the compiler flags needed by large file
407           builds and added to ccflags by hints files.
408
409       "ccname"
410           From Checkcc.U:
411
412           This can set either by hints files or by Configure.  If using gcc,
413           this is gcc, and if not, usually equal to cc, unimpressive, no?
414           Some platforms, however, make good use of this by storing the
415           flavor of the C compiler being used here.  For example if using the
416           Sun WorkShop suite, ccname will be "workshop".
417
418       "ccsymbols"
419           From Cppsym.U:
420
421           The variable contains the symbols defined by the C compiler alone.
422           The symbols defined by cpp or by cc when it calls cpp are not in
423           this list, see cppsymbols and cppccsymbols.  The list is a space-
424           separated list of symbol=value tokens.
425
426       "ccversion"
427           From Checkcc.U:
428
429           This can set either by hints files or by Configure.  If using a
430           (non-gcc) vendor cc, this variable may contain a version for the
431           compiler.
432
433       "cf_by"
434           From cf_who.U:
435
436           Login name of the person who ran the Configure script and answered
437           the questions. This is used to tag both config.sh and config_h.SH.
438
439       "cf_email"
440           From cf_email.U:
441
442           Electronic mail address of the person who ran Configure. This can
443           be used by units that require the user's e-mail, like MailList.U.
444
445       "cf_time"
446           From cf_who.U:
447
448           Holds the output of the "date" command when the configuration file
449           was produced. This is used to tag both config.sh and config_h.SH.
450
451       "charbits"
452           From charsize.U:
453
454           This variable contains the value of the "CHARBITS" symbol, which
455           indicates to the C program how many bits there are in a character.
456
457       "charsize"
458           From charsize.U:
459
460           This variable contains the value of the "CHARSIZE" symbol, which
461           indicates to the C program how many bytes there are in a character.
462
463       "chgrp"
464           From Loc.U:
465
466           This variable is defined but not used by Configure.  The value is
467           the empty string and is not useful.
468
469       "chmod"
470           From Loc.U:
471
472           This variable is used internally by Configure to determine the full
473           pathname (if any) of the chmod program.  After Configure runs, the
474           value is reset to a plain "chmod" and is not useful.
475
476       "chown"
477           From Loc.U:
478
479           This variable is defined but not used by Configure.  The value is
480           the empty string and is not useful.
481
482       "clocktype"
483           From d_times.U:
484
485           This variable holds the type returned by times(). It can be long,
486           or clock_t on "BSD" sites (in which case <sys/types.h> should be
487           included).
488
489       "comm"
490           From Loc.U:
491
492           This variable is used internally by Configure to determine the full
493           pathname (if any) of the comm program.  After Configure runs, the
494           value is reset to a plain "comm" and is not useful.
495
496       "compress"
497           From Loc.U:
498
499           This variable is defined but not used by Configure.  The value is
500           the empty string and is not useful.
501
502       "config_arg0"
503           From Options.U:
504
505           This variable contains the string used to invoke the Configure
506           command, as reported by the shell in the $0 variable.
507
508       "config_argc"
509           From Options.U:
510
511           This variable contains the number of command-line arguments passed
512           to Configure, as reported by the shell in the $# variable.  The
513           individual arguments are stored as variables config_arg1,
514           config_arg2, etc.
515
516       "config_args"
517           From Options.U:
518
519           This variable contains a single string giving the command-line
520           arguments passed to Configure. Spaces within arguments, quotes, and
521           escaped characters are not correctly preserved.  To reconstruct the
522           command line, you must assemble the individual command line pieces,
523           given in config_arg[0-9]*.
524
525       "contains"
526           From contains.U:
527
528           This variable holds the command to do a grep with a proper return
529           status.  On most sane systems it is simply "grep".  On insane
530           systems it is a grep followed by a cat followed by a test.  This
531           variable is primarily for the use of other Configure units.
532
533       "cp"
534           From Loc.U:
535
536           This variable is used internally by Configure to determine the full
537           pathname (if any) of the cp program.  After Configure runs, the
538           value is reset to a plain "cp" and is not useful.
539
540       "cpio"
541           From Loc.U:
542
543           This variable is defined but not used by Configure.  The value is
544           the empty string and is not useful.
545
546       "cpp"
547           From Loc.U:
548
549           This variable is used internally by Configure to determine the full
550           pathname (if any) of the cpp program.  After Configure runs, the
551           value is reset to a plain "cpp" and is not useful.
552
553       "cpp_stuff"
554           From cpp_stuff.U:
555
556           This variable contains an identification of the concatenation
557           mechanism used by the C preprocessor.
558
559       "cppccsymbols"
560           From Cppsym.U:
561
562           The variable contains the symbols defined by the C compiler when it
563           calls cpp.  The symbols defined by the cc alone or cpp alone are
564           not in this list, see ccsymbols and cppsymbols.  The list is a
565           space-separated list of symbol=value tokens.
566
567       "cppflags"
568           From ccflags.U:
569
570           This variable holds the flags that will be passed to the C pre-
571           processor. It is up to the Makefile to use it.
572
573       "cpplast"
574           From cppstdin.U:
575
576           This variable has the same functionality as cppminus, only it
577           applies to cpprun and not cppstdin.
578
579       "cppminus"
580           From cppstdin.U:
581
582           This variable contains the second part of the string which will
583           invoke the C preprocessor on the standard input and produce to
584           standard output.  This variable will have the value "-" if cppstdin
585           needs a minus to specify standard input, otherwise the value is "".
586
587       "cpprun"
588           From cppstdin.U:
589
590           This variable contains the command which will invoke a C
591           preprocessor on standard input and put the output to stdout. It is
592           guaranteed not to be a wrapper and may be a null string if no
593           preprocessor can be made directly available. This preprocessor
594           might be different from the one used by the C compiler. Don't
595           forget to append cpplast after the preprocessor options.
596
597       "cppstdin"
598           From cppstdin.U:
599
600           This variable contains the command which will invoke the C
601           preprocessor on standard input and put the output to stdout.  It is
602           primarily used by other Configure units that ask about preprocessor
603           symbols.
604
605       "cppsymbols"
606           From Cppsym.U:
607
608           The variable contains the symbols defined by the C preprocessor
609           alone.  The symbols defined by cc or by cc when it calls cpp are
610           not in this list, see ccsymbols and cppccsymbols.  The list is a
611           space-separated list of symbol=value tokens.
612
613       "crypt_r_proto"
614           From d_crypt_r.U:
615
616           This variable encodes the prototype of crypt_r.  It is zero if
617           d_crypt_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
618           of reentr.h if d_crypt_r is defined.
619
620       "cryptlib"
621           From d_crypt.U:
622
623           This variable holds -lcrypt or the path to a libcrypt.a archive if
624           the crypt() function is not defined in the standard C library. It
625           is up to the Makefile to use this.
626
627       "csh"
628           From Loc.U:
629
630           This variable is used internally by Configure to determine the full
631           pathname (if any) of the csh program.  After Configure runs, the
632           value is reset to a plain "csh" and is not useful.
633
634       "ctermid_r_proto"
635           From d_ctermid_r.U:
636
637           This variable encodes the prototype of ctermid_r.  It is zero if
638           d_ctermid_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
639           of reentr.h if d_ctermid_r is defined.
640
641       "ctime_r_proto"
642           From d_ctime_r.U:
643
644           This variable encodes the prototype of ctime_r.  It is zero if
645           d_ctime_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
646           of reentr.h if d_ctime_r is defined.
647
648   d
649       "d__fwalk"
650           From d__fwalk.U:
651
652           This variable conditionally defines "HAS__FWALK" if _fwalk() is
653           available to apply a function to all the file handles.
654
655       "d_accept4"
656           From d_accept4.U:
657
658           This variable conditionally defines HAS_ACCEPT4 if accept4() is
659           available to accept socket connections.
660
661       "d_access"
662           From d_access.U:
663
664           This variable conditionally defines "HAS_ACCESS" if the access()
665           system call is available to check for access permissions using real
666           IDs.
667
668       "d_accessx"
669           From d_accessx.U:
670
671           This variable conditionally defines the "HAS_ACCESSX" symbol, which
672           indicates to the C program that the accessx() routine is available.
673
674       "d_acosh"
675           From d_acosh.U:
676
677           This variable conditionally defines the "HAS_ACOSH" symbol, which
678           indicates to the C program that the acosh() routine is available.
679
680       "d_aintl"
681           From d_aintl.U:
682
683           This variable conditionally defines the "HAS_AINTL" symbol, which
684           indicates to the C program that the aintl() routine is available.
685           If copysignl is also present we can emulate modfl.
686
687       "d_alarm"
688           From d_alarm.U:
689
690           This variable conditionally defines the "HAS_ALARM" symbol, which
691           indicates to the C program that the alarm() routine is available.
692
693       "d_archlib"
694           From archlib.U:
695
696           This variable conditionally defines "ARCHLIB" to hold the pathname
697           of architecture-dependent library files for $package.  If $archlib
698           is the same as $privlib, then this is set to undef.
699
700       "d_asctime64"
701           From d_timefuncs64.U:
702
703           This variable conditionally defines the HAS_ASCTIME64 symbol, which
704           indicates to the C program that the asctime64 () routine is
705           available.
706
707       "d_asctime_r"
708           From d_asctime_r.U:
709
710           This variable conditionally defines the "HAS_ASCTIME_R" symbol,
711           which indicates to the C program that the asctime_r() routine is
712           available.
713
714       "d_asinh"
715           From d_asinh.U:
716
717           This variable conditionally defines the "HAS_ASINH" symbol, which
718           indicates to the C program that the asinh() routine is available.
719
720       "d_atanh"
721           From d_atanh.U:
722
723           This variable conditionally defines the "HAS_ATANH" symbol, which
724           indicates to the C program that the atanh() routine is available.
725
726       "d_atolf"
727           From atolf.U:
728
729           This variable conditionally defines the "HAS_ATOLF" symbol, which
730           indicates to the C program that the atolf() routine is available.
731
732       "d_atoll"
733           From atoll.U:
734
735           This variable conditionally defines the "HAS_ATOLL" symbol, which
736           indicates to the C program that the atoll() routine is available.
737
738       "d_attribute_deprecated"
739           From d_attribut.U:
740
741           This variable conditionally defines "HASATTRIBUTE_DEPRECATED",
742           which indicates that "GCC" can handle the attribute for marking
743           deprecated APIs
744
745       "d_attribute_format"
746           From d_attribut.U:
747
748           This variable conditionally defines "HASATTRIBUTE_FORMAT", which
749           indicates the C compiler can check for printf-like formats.
750
751       "d_attribute_malloc"
752           From d_attribut.U:
753
754           This variable conditionally defines "HASATTRIBUTE_MALLOC", which
755           indicates the C compiler can understand functions as having malloc-
756           like semantics.
757
758       "d_attribute_nonnull"
759           From d_attribut.U:
760
761           This variable conditionally defines "HASATTRIBUTE_NONNULL", which
762           indicates that the C compiler can know that certain arguments must
763           not be "NULL", and will check accordingly at compile time.
764
765       "d_attribute_noreturn"
766           From d_attribut.U:
767
768           This variable conditionally defines "HASATTRIBUTE_NORETURN", which
769           indicates that the C compiler can know that certain functions are
770           guaranteed never to return.
771
772       "d_attribute_pure"
773           From d_attribut.U:
774
775           This variable conditionally defines "HASATTRIBUTE_PURE", which
776           indicates that the C compiler can know that certain functions are
777           "pure" functions, meaning that they have no side effects, and only
778           rely on function input and/or global data for their results.
779
780       "d_attribute_unused"
781           From d_attribut.U:
782
783           This variable conditionally defines "HASATTRIBUTE_UNUSED", which
784           indicates that the C compiler can know that certain variables and
785           arguments may not always be used, and to not throw warnings if they
786           don't get used.
787
788       "d_attribute_warn_unused_result"
789           From d_attribut.U:
790
791           This variable conditionally defines
792           "HASATTRIBUTE_WARN_UNUSED_RESULT", which indicates that the C
793           compiler can know that certain functions have a return values that
794           must not be ignored, such as malloc() or open().
795
796       "d_backtrace"
797           From d_backtrace.U:
798
799           This variable conditionally defines the "HAS_BACKTRACE" symbol,
800           which indicates to the C program that the backtrace() routine is
801           available to get a stack trace.
802
803       "d_bsd"
804           From Guess.U:
805
806           This symbol conditionally defines the symbol "BSD" when running on
807           a "BSD" system.
808
809       "d_bsdgetpgrp"
810           From d_getpgrp.U:
811
812           This variable conditionally defines "USE_BSD_GETPGRP" if getpgrp
813           needs one arguments whereas "USG" one needs none.
814
815       "d_bsdsetpgrp"
816           From d_setpgrp.U:
817
818           This variable conditionally defines "USE_BSD_SETPGRP" if setpgrp
819           needs two arguments whereas "USG" one needs none.  See also
820           d_setpgid for a "POSIX" interface.
821
822       "d_builtin_add_overflow"
823           From d_builtin_overflow.U:
824
825           This variable conditionally defines "HAS_BUILTIN_ADD_OVERFLOW",
826           which indicates that the compiler supports
827           __builtin_add_overflow(x,y,&z) for safely adding x and y into z
828           while checking for overflow.
829
830       "d_builtin_choose_expr"
831           From d_builtin.U:
832
833           This conditionally defines "HAS_BUILTIN_CHOOSE_EXPR", which
834           indicates that the compiler supports __builtin_choose_expr(x,y,z).
835           This built-in function is analogous to the "x?y:z" operator in C,
836           except that the expression returned has its type unaltered by
837           promotion rules. Also, the built-in function does not evaluate the
838           expression that was not chosen.
839
840       "d_builtin_expect"
841           From d_builtin.U:
842
843           This conditionally defines "HAS_BUILTIN_EXPECT", which indicates
844           that the compiler supports __builtin_expect(exp,c).  You may use
845           __builtin_expect to provide the compiler with branch prediction
846           information.
847
848       "d_builtin_mul_overflow"
849           From d_builtin_overflow.U:
850
851           This variable conditionally defines "HAS_BUILTIN_MUL_OVERFLOW",
852           which indicates that the compiler supports
853           __builtin_mul_overflow(x,y,&z) for safely multiplying x and y into
854           z while checking for overflow.
855
856       "d_builtin_sub_overflow"
857           From d_builtin_overflow.U:
858
859           This variable conditionally defines "HAS_BUILTIN_SUB_OVERFLOW",
860           which indicates that the compiler supports
861           __builtin_sub_overflow(x,y,&z) for safely subtracting y from x into
862           z while checking for overflow.
863
864       "d_c99_variadic_macros"
865           From d_c99_variadic.U:
866
867           This variable conditionally defines the HAS_C99_VARIADIC_MACROS
868           symbol, which indicates to the C program that C99 variadic macros
869           are available.
870
871       "d_casti32"
872           From d_casti32.U:
873
874           This variable conditionally defines CASTI32, which indicates
875           whether the C compiler can cast large floats to 32-bit ints.
876
877       "d_castneg"
878           From d_castneg.U:
879
880           This variable conditionally defines "CASTNEG", which indicates
881           whether the C compiler can cast negative float to unsigned.
882
883       "d_cbrt"
884           From d_cbrt.U:
885
886           This variable conditionally defines the "HAS_CBRT" symbol, which
887           indicates to the C program that the cbrt() (cube root) function is
888           available.
889
890       "d_chown"
891           From d_chown.U:
892
893           This variable conditionally defines the "HAS_CHOWN" symbol, which
894           indicates to the C program that the chown() routine is available.
895
896       "d_chroot"
897           From d_chroot.U:
898
899           This variable conditionally defines the "HAS_CHROOT" symbol, which
900           indicates to the C program that the chroot() routine is available.
901
902       "d_chsize"
903           From d_chsize.U:
904
905           This variable conditionally defines the "CHSIZE" symbol, which
906           indicates to the C program that the chsize() routine is available
907           to truncate files.  You might need a -lx to get this routine.
908
909       "d_class"
910           From d_class.U:
911
912           This variable conditionally defines the "HAS_CLASS" symbol, which
913           indicates to the C program that the class() routine is available.
914
915       "d_clearenv"
916           From d_clearenv.U:
917
918           This variable conditionally defines the "HAS_CLEARENV" symbol,
919           which indicates to the C program that the clearenv () routine is
920           available.
921
922       "d_closedir"
923           From d_closedir.U:
924
925           This variable conditionally defines "HAS_CLOSEDIR" if closedir() is
926           available.
927
928       "d_cmsghdr_s"
929           From d_cmsghdr_s.U:
930
931           This variable conditionally defines the "HAS_STRUCT_CMSGHDR"
932           symbol, which indicates that the struct cmsghdr is supported.
933
934       "d_copysign"
935           From d_copysign.U:
936
937           This variable conditionally defines the "HAS_COPYSIGN" symbol,
938           which indicates to the C program that the copysign() routine is
939           available.
940
941       "d_copysignl"
942           From d_copysignl.U:
943
944           This variable conditionally defines the "HAS_COPYSIGNL" symbol,
945           which indicates to the C program that the copysignl() routine is
946           available.  If aintl is also present we can emulate modfl.
947
948       "d_cplusplus"
949           From d_cplusplus.U:
950
951           This variable conditionally defines the "USE_CPLUSPLUS" symbol,
952           which indicates that a C++ compiler was used to compiled Perl and
953           will be used to compile extensions.
954
955       "d_crypt"
956           From d_crypt.U:
957
958           This variable conditionally defines the "CRYPT" symbol, which
959           indicates to the C program that the crypt() routine is available to
960           encrypt passwords and the like.
961
962       "d_crypt_r"
963           From d_crypt_r.U:
964
965           This variable conditionally defines the "HAS_CRYPT_R" symbol, which
966           indicates to the C program that the crypt_r() routine is available.
967
968       "d_csh"
969           From d_csh.U:
970
971           This variable conditionally defines the "CSH" symbol, which
972           indicates to the C program that the C-shell exists.
973
974       "d_ctermid"
975           From d_ctermid.U:
976
977           This variable conditionally defines "CTERMID" if ctermid() is
978           available to generate filename for terminal.
979
980       "d_ctermid_r"
981           From d_ctermid_r.U:
982
983           This variable conditionally defines the "HAS_CTERMID_R" symbol,
984           which indicates to the C program that the ctermid_r() routine is
985           available.
986
987       "d_ctime64"
988           From d_timefuncs64.U:
989
990           This variable conditionally defines the HAS_CTIME64 symbol, which
991           indicates to the C program that the ctime64 () routine is
992           available.
993
994       "d_ctime_r"
995           From d_ctime_r.U:
996
997           This variable conditionally defines the "HAS_CTIME_R" symbol, which
998           indicates to the C program that the ctime_r() routine is available.
999
1000       "d_cuserid"
1001           From d_cuserid.U:
1002
1003           This variable conditionally defines the "HAS_CUSERID" symbol, which
1004           indicates to the C program that the cuserid() routine is available
1005           to get character login names.
1006
1007       "d_dbminitproto"
1008           From d_dbminitproto.U:
1009
1010           This variable conditionally defines the "HAS_DBMINIT_PROTO" symbol,
1011           which indicates to the C program that the system provides a
1012           prototype for the dbminit() function.  Otherwise, it is up to the
1013           program to supply one.
1014
1015       "d_difftime"
1016           From d_difftime.U:
1017
1018           This variable conditionally defines the "HAS_DIFFTIME" symbol,
1019           which indicates to the C program that the difftime() routine is
1020           available.
1021
1022       "d_difftime64"
1023           From d_timefuncs64.U:
1024
1025           This variable conditionally defines the HAS_DIFFTIME64 symbol,
1026           which indicates to the C program that the difftime64 () routine is
1027           available.
1028
1029       "d_dir_dd_fd"
1030           From d_dir_dd_fd.U:
1031
1032           This variable conditionally defines the "HAS_DIR_DD_FD" symbol,
1033           which indicates that the "DIR" directory stream type contains a
1034           member variable called dd_fd.
1035
1036       "d_dirfd"
1037           From d_dirfd.U:
1038
1039           This variable conditionally defines the "HAS_DIRFD" constant, which
1040           indicates to the C program that dirfd() is available to return the
1041           file descriptor of a directory stream.
1042
1043       "d_dirnamlen"
1044           From i_dirent.U:
1045
1046           This variable conditionally defines "DIRNAMLEN", which indicates to
1047           the C program that the length of directory entry names is provided
1048           by a d_namelen field.
1049
1050       "d_dladdr"
1051           From d_dladdr.U:
1052
1053           This variable conditionally defines the "HAS_DLADDR" symbol, which
1054           indicates to the C program that the dladdr() routine is available
1055           to get a stack trace.
1056
1057       "d_dlerror"
1058           From d_dlerror.U:
1059
1060           This variable conditionally defines the "HAS_DLERROR" symbol, which
1061           indicates to the C program that the dlerror() routine is available.
1062
1063       "d_dlopen"
1064           From d_dlopen.U:
1065
1066           This variable conditionally defines the "HAS_DLOPEN" symbol, which
1067           indicates to the C program that the dlopen() routine is available.
1068
1069       "d_dlsymun"
1070           From d_dlsymun.U:
1071
1072           This variable conditionally defines "DLSYM_NEEDS_UNDERSCORE", which
1073           indicates that we need to prepend an underscore to the symbol name
1074           before calling dlsym().
1075
1076       "d_dosuid"
1077           From d_dosuid.U:
1078
1079           This variable conditionally defines the symbol "DOSUID", which
1080           tells the C program that it should insert setuid emulation code on
1081           hosts which have setuid #! scripts disabled.
1082
1083       "d_double_has_inf"
1084           From longdblfio.U:
1085
1086           This variable conditionally defines the symbol "DOUBLE_HAS_INF"
1087           which indicates that the double type has an infinity.
1088
1089       "d_double_has_nan"
1090           From longdblfio.U:
1091
1092           This variable conditionally defines the symbol "DOUBLE_HAS_NAN"
1093           which indicates that the double type has a not-a-number.
1094
1095       "d_double_has_negative_zero"
1096           From longdblfio.U:
1097
1098           This variable conditionally defines the symbol
1099           "DOUBLE_HAS_NEGATIVE_ZERO" which indicates that the double type has
1100           a negative zero.
1101
1102       "d_double_has_subnormals"
1103           From longdblfio.U:
1104
1105           This variable conditionally defines the symbol
1106           "DOUBLE_HAS_SUBNORMALS" which indicates that the double type has
1107           subnormals (denormals).
1108
1109       "d_double_style_cray"
1110           From longdblfio.U:
1111
1112           This variable conditionally defines the symbol "DOUBLE_STYLE_CRAY"
1113           which indicates that the double is the 64-bit "CRAY" mainframe
1114           format.
1115
1116       "d_double_style_ibm"
1117           From longdblfio.U:
1118
1119           This variable conditionally defines the symbol "DOUBLE_STYLE_IBM",
1120           which indicates that the double is the 64-bit "IBM" mainframe
1121           format.
1122
1123       "d_double_style_ieee"
1124           From longdblfio.U:
1125
1126           This variable conditionally defines the symbol "DOUBLE_STYLE_IEEE",
1127           which indicates that the double is the 64-bit "IEEE" 754.
1128
1129       "d_double_style_vax"
1130           From longdblfio.U:
1131
1132           This variable conditionally defines the symbol "DOUBLE_STYLE_VAX",
1133           which indicates that the double is the 64-bit "VAX" format D or G.
1134
1135       "d_drand48_r"
1136           From d_drand48_r.U:
1137
1138           This variable conditionally defines the HAS_DRAND48_R symbol, which
1139           indicates to the C program that the drand48_r() routine is
1140           available.
1141
1142       "d_drand48proto"
1143           From d_drand48proto.U:
1144
1145           This variable conditionally defines the HAS_DRAND48_PROTO symbol,
1146           which indicates to the C program that the system provides a
1147           prototype for the drand48() function.  Otherwise, it is up to the
1148           program to supply one.
1149
1150       "d_dup2"
1151           From d_dup2.U:
1152
1153           This variable conditionally defines HAS_DUP2 if dup2() is available
1154           to duplicate file descriptors.
1155
1156       "d_dup3"
1157           From d_dup3.U:
1158
1159           This variable conditionally defines HAS_DUP3 if dup3() is available
1160           to duplicate file descriptors.
1161
1162       "d_duplocale"
1163           From d_newlocale.U:
1164
1165           This variable conditionally defines the "HAS_DUPLOCALE" symbol,
1166           which indicates to the C program that the duplocale() routine is
1167           available to duplicate a locale object.
1168
1169       "d_eaccess"
1170           From d_eaccess.U:
1171
1172           This variable conditionally defines the "HAS_EACCESS" symbol, which
1173           indicates to the C program that the eaccess() routine is available.
1174
1175       "d_endgrent"
1176           From d_endgrent.U:
1177
1178           This variable conditionally defines the "HAS_ENDGRENT" symbol,
1179           which indicates to the C program that the endgrent() routine is
1180           available for sequential access of the group database.
1181
1182       "d_endgrent_r"
1183           From d_endgrent_r.U:
1184
1185           This variable conditionally defines the "HAS_ENDGRENT_R" symbol,
1186           which indicates to the C program that the endgrent_r() routine is
1187           available.
1188
1189       "d_endhent"
1190           From d_endhent.U:
1191
1192           This variable conditionally defines "HAS_ENDHOSTENT" if
1193           endhostent() is available to close whatever was being used for host
1194           queries.
1195
1196       "d_endhostent_r"
1197           From d_endhostent_r.U:
1198
1199           This variable conditionally defines the "HAS_ENDHOSTENT_R" symbol,
1200           which indicates to the C program that the endhostent_r() routine is
1201           available.
1202
1203       "d_endnent"
1204           From d_endnent.U:
1205
1206           This variable conditionally defines "HAS_ENDNETENT" if endnetent()
1207           is available to close whatever was being used for network queries.
1208
1209       "d_endnetent_r"
1210           From d_endnetent_r.U:
1211
1212           This variable conditionally defines the "HAS_ENDNETENT_R" symbol,
1213           which indicates to the C program that the endnetent_r() routine is
1214           available.
1215
1216       "d_endpent"
1217           From d_endpent.U:
1218
1219           This variable conditionally defines "HAS_ENDPROTOENT" if
1220           endprotoent() is available to close whatever was being used for
1221           protocol queries.
1222
1223       "d_endprotoent_r"
1224           From d_endprotoent_r.U:
1225
1226           This variable conditionally defines the "HAS_ENDPROTOENT_R" symbol,
1227           which indicates to the C program that the endprotoent_r() routine
1228           is available.
1229
1230       "d_endpwent"
1231           From d_endpwent.U:
1232
1233           This variable conditionally defines the "HAS_ENDPWENT" symbol,
1234           which indicates to the C program that the endpwent() routine is
1235           available for sequential access of the passwd database.
1236
1237       "d_endpwent_r"
1238           From d_endpwent_r.U:
1239
1240           This variable conditionally defines the "HAS_ENDPWENT_R" symbol,
1241           which indicates to the C program that the endpwent_r() routine is
1242           available.
1243
1244       "d_endsent"
1245           From d_endsent.U:
1246
1247           This variable conditionally defines "HAS_ENDSERVENT" if
1248           endservent() is available to close whatever was being used for
1249           service queries.
1250
1251       "d_endservent_r"
1252           From d_endservent_r.U:
1253
1254           This variable conditionally defines the "HAS_ENDSERVENT_R" symbol,
1255           which indicates to the C program that the endservent_r() routine is
1256           available.
1257
1258       "d_eofnblk"
1259           From nblock_io.U:
1260
1261           This variable conditionally defines "EOF_NONBLOCK" if "EOF" can be
1262           seen when reading from a non-blocking I/O source.
1263
1264       "d_erf"
1265           From d_erf.U:
1266
1267           This variable conditionally defines the "HAS_ERF" symbol, which
1268           indicates to the C program that the erf() routine is available.
1269
1270       "d_erfc"
1271           From d_erfc.U:
1272
1273           This variable conditionally defines the "HAS_ERFC" symbol, which
1274           indicates to the C program that the erfc() routine is available.
1275
1276       "d_eunice"
1277           From Guess.U:
1278
1279           This variable conditionally defines the symbols "EUNICE" and "VAX",
1280           which alerts the C program that it must deal with idiosyncrasies of
1281           "VMS".
1282
1283       "d_exp2"
1284           From d_exp2.U:
1285
1286           This variable conditionally defines the HAS_EXP2 symbol, which
1287           indicates to the C program that the exp2() routine is available.
1288
1289       "d_expm1"
1290           From d_expm1.U:
1291
1292           This variable conditionally defines the HAS_EXPM1 symbol, which
1293           indicates to the C program that the expm1() routine is available.
1294
1295       "d_faststdio"
1296           From d_faststdio.U:
1297
1298           This variable conditionally defines the "HAS_FAST_STDIO" symbol,
1299           which indicates to the C program that the "fast stdio" is available
1300           to manipulate the stdio buffers directly.
1301
1302       "d_fchdir"
1303           From d_fchdir.U:
1304
1305           This variable conditionally defines the "HAS_FCHDIR" symbol, which
1306           indicates to the C program that the fchdir() routine is available.
1307
1308       "d_fchmod"
1309           From d_fchmod.U:
1310
1311           This variable conditionally defines the "HAS_FCHMOD" symbol, which
1312           indicates to the C program that the fchmod() routine is available
1313           to change mode of opened files.
1314
1315       "d_fchmodat"
1316           From d_fsat.U:
1317
1318           This variable conditionally defines the "HAS_FCHMODAT" symbol,
1319           which indicates the "POSIX" fchmodat() function is available.
1320
1321       "d_fchown"
1322           From d_fchown.U:
1323
1324           This variable conditionally defines the "HAS_FCHOWN" symbol, which
1325           indicates to the C program that the fchown() routine is available
1326           to change ownership of opened files.
1327
1328       "d_fcntl"
1329           From d_fcntl.U:
1330
1331           This variable conditionally defines the "HAS_FCNTL" symbol, and
1332           indicates whether the fcntl() function exists
1333
1334       "d_fcntl_can_lock"
1335           From d_fcntl_can_lock.U:
1336
1337           This variable conditionally defines the "FCNTL_CAN_LOCK" symbol and
1338           indicates whether file locking with fcntl() works.
1339
1340       "d_fd_macros"
1341           From d_fd_set.U:
1342
1343           This variable contains the eventual value of the "HAS_FD_MACROS"
1344           symbol, which indicates if your C compiler knows about the macros
1345           which manipulate an fd_set.
1346
1347       "d_fd_set"
1348           From d_fd_set.U:
1349
1350           This variable contains the eventual value of the "HAS_FD_SET"
1351           symbol, which indicates if your C compiler knows about the fd_set
1352           typedef.
1353
1354       "d_fdclose"
1355           From d_fdclose.U:
1356
1357           This variable conditionally defines the "HAS_FDCLOSE" symbol, which
1358           indicates to the C program that the fdclose() routine is available.
1359
1360       "d_fdim"
1361           From d_fdim.U:
1362
1363           This variable conditionally defines the "HAS_FDIM" symbol, which
1364           indicates to the C program that the fdim() routine is available.
1365
1366       "d_fds_bits"
1367           From d_fd_set.U:
1368
1369           This variable contains the eventual value of the "HAS_FDS_BITS"
1370           symbol, which indicates if your fd_set typedef contains the
1371           fds_bits member.  If you have an fd_set typedef, but the dweebs who
1372           installed it did a half-fast job and neglected to provide the
1373           macros to manipulate an fd_set, "HAS_FDS_BITS" will let us know how
1374           to fix the gaffe.
1375
1376       "d_fegetround"
1377           From d_fegetround.U:
1378
1379           This variable conditionally defines "HAS_FEGETROUND" if
1380           fegetround() is available to get the floating point rounding mode.
1381
1382       "d_fgetpos"
1383           From d_fgetpos.U:
1384
1385           This variable conditionally defines "HAS_FGETPOS" if fgetpos() is
1386           available to get the file position indicator.
1387
1388       "d_finite"
1389           From d_finite.U:
1390
1391           This variable conditionally defines the "HAS_FINITE" symbol, which
1392           indicates to the C program that the finite() routine is available.
1393
1394       "d_finitel"
1395           From d_finitel.U:
1396
1397           This variable conditionally defines the "HAS_FINITEL" symbol, which
1398           indicates to the C program that the finitel() routine is available.
1399
1400       "d_flexfnam"
1401           From d_flexfnam.U:
1402
1403           This variable conditionally defines the "FLEXFILENAMES" symbol,
1404           which indicates that the system supports filenames longer than 14
1405           characters.
1406
1407       "d_flock"
1408           From d_flock.U:
1409
1410           This variable conditionally defines "HAS_FLOCK" if flock() is
1411           available to do file locking.
1412
1413       "d_flockproto"
1414           From d_flockproto.U:
1415
1416           This variable conditionally defines the "HAS_FLOCK_PROTO" symbol,
1417           which indicates to the C program that the system provides a
1418           prototype for the flock() function.  Otherwise, it is up to the
1419           program to supply one.
1420
1421       "d_fma"
1422           From d_fma.U:
1423
1424           This variable conditionally defines the "HAS_FMA" symbol, which
1425           indicates to the C program that the fma() routine is available.
1426
1427       "d_fmax"
1428           From d_fmax.U:
1429
1430           This variable conditionally defines the "HAS_FMAX" symbol, which
1431           indicates to the C program that the fmax() routine is available.
1432
1433       "d_fmin"
1434           From d_fmin.U:
1435
1436           This variable conditionally defines the "HAS_FMIN" symbol, which
1437           indicates to the C program that the fmin() routine is available.
1438
1439       "d_fork"
1440           From d_fork.U:
1441
1442           This variable conditionally defines the "HAS_FORK" symbol, which
1443           indicates to the C program that the fork() routine is available.
1444
1445       "d_fp_class"
1446           From d_fp_class.U:
1447
1448           This variable conditionally defines the "HAS_FP_CLASS" symbol,
1449           which indicates to the C program that the fp_class() routine is
1450           available.
1451
1452       "d_fp_classify"
1453           From d_fpclassify.U:
1454
1455           This variable conditionally defines the "HAS_FP_CLASSIFY" symbol,
1456           which indicates to the C program that the fp_classify() routine is
1457           available.
1458
1459       "d_fp_classl"
1460           From d_fp_classl.U:
1461
1462           This variable conditionally defines the "HAS_FP_CLASSL" symbol,
1463           which indicates to the C program that the fp_classl() routine is
1464           available.
1465
1466       "d_fpathconf"
1467           From d_pathconf.U:
1468
1469           This variable conditionally defines the "HAS_FPATHCONF" symbol,
1470           which indicates to the C program that the pathconf() routine is
1471           available to determine file-system related limits and options
1472           associated with a given open file descriptor.
1473
1474       "d_fpclass"
1475           From d_fpclass.U:
1476
1477           This variable conditionally defines the "HAS_FPCLASS" symbol, which
1478           indicates to the C program that the fpclass() routine is available.
1479
1480       "d_fpclassify"
1481           From d_fpclassify.U:
1482
1483           This variable conditionally defines the "HAS_FPCLASSIFY" symbol,
1484           which indicates to the C program that the fpclassify() routine is
1485           available.
1486
1487       "d_fpclassl"
1488           From d_fpclassl.U:
1489
1490           This variable conditionally defines the "HAS_FPCLASSL" symbol,
1491           which indicates to the C program that the fpclassl() routine is
1492           available.
1493
1494       "d_fpgetround"
1495           From d_fpgetround.U:
1496
1497           This variable conditionally defines "HAS_FPGETROUND" if
1498           fpgetround() is available to get the floating point rounding mode.
1499
1500       "d_fpos64_t"
1501           From d_fpos64_t.U:
1502
1503           This symbol will be defined if the C compiler supports fpos64_t.
1504
1505       "d_freelocale"
1506           From d_newlocale.U:
1507
1508           This variable conditionally defines the "HAS_FREELOCALE" symbol,
1509           which indicates to the C program that the freelocale() routine is
1510           available to deallocates the resources associated with a locale
1511           object.
1512
1513       "d_frexpl"
1514           From d_frexpl.U:
1515
1516           This variable conditionally defines the "HAS_FREXPL" symbol, which
1517           indicates to the C program that the frexpl() routine is available.
1518
1519       "d_fs_data_s"
1520           From d_fs_data_s.U:
1521
1522           This variable conditionally defines the "HAS_STRUCT_FS_DATA"
1523           symbol, which indicates that the struct fs_data is supported.
1524
1525       "d_fseeko"
1526           From d_fseeko.U:
1527
1528           This variable conditionally defines the "HAS_FSEEKO" symbol, which
1529           indicates to the C program that the fseeko() routine is available.
1530
1531       "d_fsetpos"
1532           From d_fsetpos.U:
1533
1534           This variable conditionally defines "HAS_FSETPOS" if fsetpos() is
1535           available to set the file position indicator.
1536
1537       "d_fstatfs"
1538           From d_fstatfs.U:
1539
1540           This variable conditionally defines the "HAS_FSTATFS" symbol, which
1541           indicates to the C program that the fstatfs() routine is available.
1542
1543       "d_fstatvfs"
1544           From d_statvfs.U:
1545
1546           This variable conditionally defines the "HAS_FSTATVFS" symbol,
1547           which indicates to the C program that the fstatvfs() routine is
1548           available.
1549
1550       "d_fsync"
1551           From d_fsync.U:
1552
1553           This variable conditionally defines the "HAS_FSYNC" symbol, which
1554           indicates to the C program that the fsync() routine is available.
1555
1556       "d_ftello"
1557           From d_ftello.U:
1558
1559           This variable conditionally defines the "HAS_FTELLO" symbol, which
1560           indicates to the C program that the ftello() routine is available.
1561
1562       "d_ftime"
1563           From d_ftime.U:
1564
1565           This variable conditionally defines the "HAS_FTIME" symbol, which
1566           indicates that the ftime() routine exists.  The ftime() routine is
1567           basically a sub-second accuracy clock.
1568
1569       "d_futimes"
1570           From d_futimes.U:
1571
1572           This variable conditionally defines the "HAS_FUTIMES" symbol, which
1573           indicates to the C program that the futimes() routine is available.
1574
1575       "d_gai_strerror"
1576           From d_gai_strerror.U:
1577
1578           This variable conditionally defines the "HAS_GAI_STRERROR" symbol
1579           if the gai_strerror() routine is available and can be used to
1580           translate error codes returned by getaddrinfo() into human readable
1581           strings.
1582
1583       "d_Gconvert"
1584           From d_gconvert.U:
1585
1586           This variable holds what Gconvert is defined as to convert floating
1587           point numbers into strings.  By default, Configure sets "this"
1588           macro to use the first of gconvert, gcvt, or sprintf that pass
1589           sprintf-%g-like behavior tests.  If perl is using long doubles, the
1590           macro uses the first of the following functions that pass
1591           Configure's tests: qgcvt, sprintf (if Configure knows how to make
1592           sprintf format long doubles--see sPRIgldbl), gconvert, gcvt, and
1593           sprintf (casting to double).  The gconvert_preference and
1594           gconvert_ld_preference variables can be used to alter Configure's
1595           preferences, for doubles and long doubles, respectively.  If
1596           present, they contain a space-separated list of one or more of the
1597           above function names in the order they should be tried.
1598
1599           d_Gconvert may be set to override Configure with a platform-
1600           specific function.  If this function expects a double, a different
1601           value may need to be set by the uselongdouble.cbu call-back unit so
1602           that long doubles can be formatted without loss of precision.
1603
1604       "d_gdbm_ndbm_h_uses_prototypes"
1605           From i_ndbm.U:
1606
1607           This variable conditionally defines the "NDBM_H_USES_PROTOTYPES"
1608           symbol, which indicates that the gdbm-ndbm.h include file uses real
1609           "ANSI" C prototypes instead of K&R style function declarations. K&R
1610           style declarations are unsupported in C++, so the include file
1611           requires special handling when using a C++ compiler and this
1612           variable is undefined. Consult the different
1613           d_*ndbm_h_uses_prototypes variables to get the same information for
1614           alternative ndbm.h include files.
1615
1616       "d_gdbmndbm_h_uses_prototypes"
1617           From i_ndbm.U:
1618
1619           This variable conditionally defines the "NDBM_H_USES_PROTOTYPES"
1620           symbol, which indicates that the gdbm/ndbm.h include file uses real
1621           "ANSI" C prototypes instead of K&R style function declarations. K&R
1622           style declarations are unsupported in C++, so the include file
1623           requires special handling when using a C++ compiler and this
1624           variable is undefined. Consult the different
1625           d_*ndbm_h_uses_prototypes variables to get the same information for
1626           alternative ndbm.h include files.
1627
1628       "d_getaddrinfo"
1629           From d_getaddrinfo.U:
1630
1631           This variable conditionally defines the "HAS_GETADDRINFO" symbol,
1632           which indicates to the C program that the getaddrinfo() function is
1633           available.
1634
1635       "d_getcwd"
1636           From d_getcwd.U:
1637
1638           This variable conditionally defines the "HAS_GETCWD" symbol, which
1639           indicates to the C program that the getcwd() routine is available
1640           to get the current working directory.
1641
1642       "d_getespwnam"
1643           From d_getespwnam.U:
1644
1645           This variable conditionally defines "HAS_GETESPWNAM" if
1646           getespwnam() is available to retrieve enhanced (shadow) password
1647           entries by name.
1648
1649       "d_getfsstat"
1650           From d_getfsstat.U:
1651
1652           This variable conditionally defines the "HAS_GETFSSTAT" symbol,
1653           which indicates to the C program that the getfsstat() routine is
1654           available.
1655
1656       "d_getgrent"
1657           From d_getgrent.U:
1658
1659           This variable conditionally defines the "HAS_GETGRENT" symbol,
1660           which indicates to the C program that the getgrent() routine is
1661           available for sequential access of the group database.
1662
1663       "d_getgrent_r"
1664           From d_getgrent_r.U:
1665
1666           This variable conditionally defines the "HAS_GETGRENT_R" symbol,
1667           which indicates to the C program that the getgrent_r() routine is
1668           available.
1669
1670       "d_getgrgid_r"
1671           From d_getgrgid_r.U:
1672
1673           This variable conditionally defines the "HAS_GETGRGID_R" symbol,
1674           which indicates to the C program that the getgrgid_r() routine is
1675           available.
1676
1677       "d_getgrnam_r"
1678           From d_getgrnam_r.U:
1679
1680           This variable conditionally defines the "HAS_GETGRNAM_R" symbol,
1681           which indicates to the C program that the getgrnam_r() routine is
1682           available.
1683
1684       "d_getgrps"
1685           From d_getgrps.U:
1686
1687           This variable conditionally defines the "HAS_GETGROUPS" symbol,
1688           which indicates to the C program that the getgroups() routine is
1689           available to get the list of process groups.
1690
1691       "d_gethbyaddr"
1692           From d_gethbyad.U:
1693
1694           This variable conditionally defines the "HAS_GETHOSTBYADDR" symbol,
1695           which indicates to the C program that the gethostbyaddr() routine
1696           is available to look up hosts by their "IP" addresses.
1697
1698       "d_gethbyname"
1699           From d_gethbynm.U:
1700
1701           This variable conditionally defines the "HAS_GETHOSTBYNAME" symbol,
1702           which indicates to the C program that the gethostbyname() routine
1703           is available to look up host names in some data base or other.
1704
1705       "d_gethent"
1706           From d_gethent.U:
1707
1708           This variable conditionally defines "HAS_GETHOSTENT" if
1709           gethostent() is available to look up host names in some data base
1710           or another.
1711
1712       "d_gethname"
1713           From d_gethname.U:
1714
1715           This variable conditionally defines the "HAS_GETHOSTNAME" symbol,
1716           which indicates to the C program that the gethostname() routine may
1717           be used to derive the host name.
1718
1719       "d_gethostbyaddr_r"
1720           From d_gethostbyaddr_r.U:
1721
1722           This variable conditionally defines the "HAS_GETHOSTBYADDR_R"
1723           symbol, which indicates to the C program that the gethostbyaddr_r()
1724           routine is available.
1725
1726       "d_gethostbyname_r"
1727           From d_gethostbyname_r.U:
1728
1729           This variable conditionally defines the "HAS_GETHOSTBYNAME_R"
1730           symbol, which indicates to the C program that the gethostbyname_r()
1731           routine is available.
1732
1733       "d_gethostent_r"
1734           From d_gethostent_r.U:
1735
1736           This variable conditionally defines the "HAS_GETHOSTENT_R" symbol,
1737           which indicates to the C program that the gethostent_r() routine is
1738           available.
1739
1740       "d_gethostprotos"
1741           From d_gethostprotos.U:
1742
1743           This variable conditionally defines the "HAS_GETHOST_PROTOS"
1744           symbol, which indicates to the C program that <netdb.h> supplies
1745           prototypes for the various gethost*() functions.  See also
1746           netdbtype.U for probing for various netdb types.
1747
1748       "d_getitimer"
1749           From d_getitimer.U:
1750
1751           This variable conditionally defines the "HAS_GETITIMER" symbol,
1752           which indicates to the C program that the getitimer() routine is
1753           available.
1754
1755       "d_getlogin"
1756           From d_getlogin.U:
1757
1758           This variable conditionally defines the "HAS_GETLOGIN" symbol,
1759           which indicates to the C program that the getlogin() routine is
1760           available to get the login name.
1761
1762       "d_getlogin_r"
1763           From d_getlogin_r.U:
1764
1765           This variable conditionally defines the "HAS_GETLOGIN_R" symbol,
1766           which indicates to the C program that the getlogin_r() routine is
1767           available.
1768
1769       "d_getmnt"
1770           From d_getmnt.U:
1771
1772           This variable conditionally defines the "HAS_GETMNT" symbol, which
1773           indicates to the C program that the getmnt() routine is available
1774           to retrieve one or more mount info blocks by filename.
1775
1776       "d_getmntent"
1777           From d_getmntent.U:
1778
1779           This variable conditionally defines the "HAS_GETMNTENT" symbol,
1780           which indicates to the C program that the getmntent() routine is
1781           available to iterate through mounted files to get their mount info.
1782
1783       "d_getnameinfo"
1784           From d_getnameinfo.U:
1785
1786           This variable conditionally defines the "HAS_GETNAMEINFO" symbol,
1787           which indicates to the C program that the getnameinfo() function is
1788           available.
1789
1790       "d_getnbyaddr"
1791           From d_getnbyad.U:
1792
1793           This variable conditionally defines the "HAS_GETNETBYADDR" symbol,
1794           which indicates to the C program that the getnetbyaddr() routine is
1795           available to look up networks by their "IP" addresses.
1796
1797       "d_getnbyname"
1798           From d_getnbynm.U:
1799
1800           This variable conditionally defines the "HAS_GETNETBYNAME" symbol,
1801           which indicates to the C program that the getnetbyname() routine is
1802           available to look up networks by their names.
1803
1804       "d_getnent"
1805           From d_getnent.U:
1806
1807           This variable conditionally defines "HAS_GETNETENT" if getnetent()
1808           is available to look up network names in some data base or another.
1809
1810       "d_getnetbyaddr_r"
1811           From d_getnetbyaddr_r.U:
1812
1813           This variable conditionally defines the "HAS_GETNETBYADDR_R"
1814           symbol, which indicates to the C program that the getnetbyaddr_r()
1815           routine is available.
1816
1817       "d_getnetbyname_r"
1818           From d_getnetbyname_r.U:
1819
1820           This variable conditionally defines the "HAS_GETNETBYNAME_R"
1821           symbol, which indicates to the C program that the getnetbyname_r()
1822           routine is available.
1823
1824       "d_getnetent_r"
1825           From d_getnetent_r.U:
1826
1827           This variable conditionally defines the "HAS_GETNETENT_R" symbol,
1828           which indicates to the C program that the getnetent_r() routine is
1829           available.
1830
1831       "d_getnetprotos"
1832           From d_getnetprotos.U:
1833
1834           This variable conditionally defines the "HAS_GETNET_PROTOS" symbol,
1835           which indicates to the C program that <netdb.h> supplies prototypes
1836           for the various getnet*() functions.  See also netdbtype.U for
1837           probing for various netdb types.
1838
1839       "d_getpagsz"
1840           From d_getpagsz.U:
1841
1842           This variable conditionally defines "HAS_GETPAGESIZE" if
1843           getpagesize() is available to get the system page size.
1844
1845       "d_getpbyname"
1846           From d_getprotby.U:
1847
1848           This variable conditionally defines the "HAS_GETPROTOBYNAME"
1849           symbol, which indicates to the C program that the getprotobyname()
1850           routine is available to look up protocols by their name.
1851
1852       "d_getpbynumber"
1853           From d_getprotby.U:
1854
1855           This variable conditionally defines the "HAS_GETPROTOBYNUMBER"
1856           symbol, which indicates to the C program that the
1857           getprotobynumber() routine is available to look up protocols by
1858           their number.
1859
1860       "d_getpent"
1861           From d_getpent.U:
1862
1863           This variable conditionally defines "HAS_GETPROTOENT" if
1864           getprotoent() is available to look up protocols in some data base
1865           or another.
1866
1867       "d_getpgid"
1868           From d_getpgid.U:
1869
1870           This variable conditionally defines the "HAS_GETPGID" symbol, which
1871           indicates to the C program that the getpgid(pid) function is
1872           available to get the process group id.
1873
1874       "d_getpgrp"
1875           From d_getpgrp.U:
1876
1877           This variable conditionally defines "HAS_GETPGRP" if getpgrp() is
1878           available to get the current process group.
1879
1880       "d_getpgrp2"
1881           From d_getpgrp2.U:
1882
1883           This variable conditionally defines the HAS_GETPGRP2 symbol, which
1884           indicates to the C program that the getpgrp2() (as in DG/"UX")
1885           routine is available to get the current process group.
1886
1887       "d_getppid"
1888           From d_getppid.U:
1889
1890           This variable conditionally defines the "HAS_GETPPID" symbol, which
1891           indicates to the C program that the getppid() routine is available
1892           to get the parent process "ID".
1893
1894       "d_getprior"
1895           From d_getprior.U:
1896
1897           This variable conditionally defines "HAS_GETPRIORITY" if
1898           getpriority() is available to get a process's priority.
1899
1900       "d_getprotobyname_r"
1901           From d_getprotobyname_r.U:
1902
1903           This variable conditionally defines the "HAS_GETPROTOBYNAME_R"
1904           symbol, which indicates to the C program that the
1905           getprotobyname_r() routine is available.
1906
1907       "d_getprotobynumber_r"
1908           From d_getprotobynumber_r.U:
1909
1910           This variable conditionally defines the "HAS_GETPROTOBYNUMBER_R"
1911           symbol, which indicates to the C program that the
1912           getprotobynumber_r() routine is available.
1913
1914       "d_getprotoent_r"
1915           From d_getprotoent_r.U:
1916
1917           This variable conditionally defines the "HAS_GETPROTOENT_R" symbol,
1918           which indicates to the C program that the getprotoent_r() routine
1919           is available.
1920
1921       "d_getprotoprotos"
1922           From d_getprotoprotos.U:
1923
1924           This variable conditionally defines the "HAS_GETPROTO_PROTOS"
1925           symbol, which indicates to the C program that <netdb.h> supplies
1926           prototypes for the various getproto*() functions.  See also
1927           netdbtype.U for probing for various netdb types.
1928
1929       "d_getprpwnam"
1930           From d_getprpwnam.U:
1931
1932           This variable conditionally defines "HAS_GETPRPWNAM" if
1933           getprpwnam() is available to retrieve protected (shadow) password
1934           entries by name.
1935
1936       "d_getpwent"
1937           From d_getpwent.U:
1938
1939           This variable conditionally defines the "HAS_GETPWENT" symbol,
1940           which indicates to the C program that the getpwent() routine is
1941           available for sequential access of the passwd database.
1942
1943       "d_getpwent_r"
1944           From d_getpwent_r.U:
1945
1946           This variable conditionally defines the "HAS_GETPWENT_R" symbol,
1947           which indicates to the C program that the getpwent_r() routine is
1948           available.
1949
1950       "d_getpwnam_r"
1951           From d_getpwnam_r.U:
1952
1953           This variable conditionally defines the "HAS_GETPWNAM_R" symbol,
1954           which indicates to the C program that the getpwnam_r() routine is
1955           available.
1956
1957       "d_getpwuid_r"
1958           From d_getpwuid_r.U:
1959
1960           This variable conditionally defines the "HAS_GETPWUID_R" symbol,
1961           which indicates to the C program that the getpwuid_r() routine is
1962           available.
1963
1964       "d_getsbyname"
1965           From d_getsrvby.U:
1966
1967           This variable conditionally defines the "HAS_GETSERVBYNAME" symbol,
1968           which indicates to the C program that the getservbyname() routine
1969           is available to look up services by their name.
1970
1971       "d_getsbyport"
1972           From d_getsrvby.U:
1973
1974           This variable conditionally defines the "HAS_GETSERVBYPORT" symbol,
1975           which indicates to the C program that the getservbyport() routine
1976           is available to look up services by their port.
1977
1978       "d_getsent"
1979           From d_getsent.U:
1980
1981           This variable conditionally defines "HAS_GETSERVENT" if
1982           getservent() is available to look up network services in some data
1983           base or another.
1984
1985       "d_getservbyname_r"
1986           From d_getservbyname_r.U:
1987
1988           This variable conditionally defines the "HAS_GETSERVBYNAME_R"
1989           symbol, which indicates to the C program that the getservbyname_r()
1990           routine is available.
1991
1992       "d_getservbyport_r"
1993           From d_getservbyport_r.U:
1994
1995           This variable conditionally defines the "HAS_GETSERVBYPORT_R"
1996           symbol, which indicates to the C program that the getservbyport_r()
1997           routine is available.
1998
1999       "d_getservent_r"
2000           From d_getservent_r.U:
2001
2002           This variable conditionally defines the "HAS_GETSERVENT_R" symbol,
2003           which indicates to the C program that the getservent_r() routine is
2004           available.
2005
2006       "d_getservprotos"
2007           From d_getservprotos.U:
2008
2009           This variable conditionally defines the "HAS_GETSERV_PROTOS"
2010           symbol, which indicates to the C program that <netdb.h> supplies
2011           prototypes for the various getserv*() functions.  See also
2012           netdbtype.U for probing for various netdb types.
2013
2014       "d_getspnam"
2015           From d_getspnam.U:
2016
2017           This variable conditionally defines "HAS_GETSPNAM" if getspnam() is
2018           available to retrieve SysV shadow password entries by name.
2019
2020       "d_getspnam_r"
2021           From d_getspnam_r.U:
2022
2023           This variable conditionally defines the "HAS_GETSPNAM_R" symbol,
2024           which indicates to the C program that the getspnam_r() routine is
2025           available.
2026
2027       "d_gettimeod"
2028           From d_ftime.U:
2029
2030           This variable conditionally defines the "HAS_GETTIMEOFDAY" symbol,
2031           which indicates that the gettimeofday() system call exists (to
2032           obtain a sub-second accuracy clock). You should probably include
2033           <sys/resource.h>.
2034
2035       "d_gmtime64"
2036           From d_timefuncs64.U:
2037
2038           This variable conditionally defines the HAS_GMTIME64 symbol, which
2039           indicates to the C program that the gmtime64 () routine is
2040           available.
2041
2042       "d_gmtime_r"
2043           From d_gmtime_r.U:
2044
2045           This variable conditionally defines the "HAS_GMTIME_R" symbol,
2046           which indicates to the C program that the gmtime_r() routine is
2047           available.
2048
2049       "d_gnulibc"
2050           From d_gnulibc.U:
2051
2052           Defined if we're dealing with the "GNU" C Library.
2053
2054       "d_grpasswd"
2055           From i_grp.U:
2056
2057           This variable conditionally defines "GRPASSWD", which indicates
2058           that struct group in <grp.h> contains gr_passwd.
2059
2060       "d_has_C_UTF8"
2061           From d_setlocale.U:
2062
2063           This variable is set to either "true" or "false" depending on
2064           whether the compilation system supports the C.UTF-8 locale.
2065
2066       "d_hasmntopt"
2067           From d_hasmntopt.U:
2068
2069           This variable conditionally defines the "HAS_HASMNTOPT" symbol,
2070           which indicates to the C program that the hasmntopt() routine is
2071           available to query the mount options of file systems.
2072
2073       "d_htonl"
2074           From d_htonl.U:
2075
2076           This variable conditionally defines "HAS_HTONL" if htonl() and its
2077           friends are available to do network order byte swapping.
2078
2079       "d_hypot"
2080           From d_hypot.U:
2081
2082           This variable conditionally defines "HAS_HYPOT" if hypot is
2083           available for numerically stable hypotenuse function.
2084
2085       "d_ilogb"
2086           From d_ilogb.U:
2087
2088           This variable conditionally defines the "HAS_ILOGB" symbol, which
2089           indicates to the C program that the ilogb() routine is available
2090           for extracting the exponent of double x as a signed integer.
2091
2092       "d_ilogbl"
2093           From d_ilogbl.U:
2094
2095           This variable conditionally defines the "HAS_ILOGBL" symbol, which
2096           indicates to the C program that the ilogbl() routine is available
2097           for extracting the exponent of long double x as a signed integer.
2098           If scalbnl is also present we can emulate frexpl.
2099
2100       "d_inc_version_list"
2101           From inc_version_list.U:
2102
2103           This variable conditionally defines "PERL_INC_VERSION_LIST".  It is
2104           set to undef when "PERL_INC_VERSION_LIST" is empty.
2105
2106       "d_inetaton"
2107           From d_inetaton.U:
2108
2109           This variable conditionally defines the "HAS_INET_ATON" symbol,
2110           which indicates to the C program that the inet_aton() function is
2111           available to parse "IP" address "dotted-quad" strings.
2112
2113       "d_inetntop"
2114           From d_inetntop.U:
2115
2116           This variable conditionally defines the "HAS_INETNTOP" symbol,
2117           which indicates to the C program that the inet_ntop() function is
2118           available.
2119
2120       "d_inetpton"
2121           From d_inetpton.U:
2122
2123           This variable conditionally defines the "HAS_INETPTON" symbol,
2124           which indicates to the C program that the inet_pton() function is
2125           available.
2126
2127       "d_int64_t"
2128           From d_int64_t.U:
2129
2130           This symbol will be defined if the C compiler supports int64_t.
2131
2132       "d_ip_mreq"
2133           From d_socket.U:
2134
2135           This variable conditionally defines the "HAS_IP_MREQ" symbol, which
2136           indicates the availability of a struct ip_mreq.
2137
2138       "d_ip_mreq_source"
2139           From d_socket.U:
2140
2141           This variable conditionally defines the "HAS_IP_MREQ_SOURCE"
2142           symbol, which indicates the availability of a struct
2143           ip_mreq_source.
2144
2145       "d_ipv6_mreq"
2146           From d_socket.U:
2147
2148           This variable conditionally defines the HAS_IPV6_MREQ symbol, which
2149           indicates the availability of a struct ipv6_mreq.
2150
2151       "d_ipv6_mreq_source"
2152           From d_socket.U:
2153
2154           This variable conditionally defines the HAS_IPV6_MREQ_SOURCE
2155           symbol, which indicates the availability of a struct
2156           ipv6_mreq_source.
2157
2158       "d_isascii"
2159           From d_isascii.U:
2160
2161           This variable conditionally defines the "HAS_ISASCII" constant,
2162           which indicates to the C program that isascii() is available.
2163
2164       "d_isblank"
2165           From d_isblank.U:
2166
2167           This variable conditionally defines the "HAS_ISBLANK" constant,
2168           which indicates to the C program that isblank() is available.
2169
2170       "d_isfinite"
2171           From d_isfinite.U:
2172
2173           This variable conditionally defines the "HAS_ISFINITE" symbol,
2174           which indicates to the C program that the isfinite() routine is
2175           available.
2176
2177       "d_isfinitel"
2178           From d_isfinitel.U:
2179
2180           This variable conditionally defines the "HAS_ISFINITEL" symbol,
2181           which indicates to the C program that the isfinitel() routine is
2182           available.
2183
2184       "d_isinf"
2185           From d_isinf.U:
2186
2187           This variable conditionally defines the "HAS_ISINF" symbol, which
2188           indicates to the C program that the isinf() routine is available.
2189
2190       "d_isinfl"
2191           From d_isinfl.U:
2192
2193           This variable conditionally defines the "HAS_ISINFL" symbol, which
2194           indicates to the C program that the isinfl() routine is available.
2195
2196       "d_isless"
2197           From d_isless.U:
2198
2199           This variable conditionally defines the "HAS_ISLESS" symbol, which
2200           indicates to the C program that the isless() routine is available.
2201
2202       "d_isnan"
2203           From d_isnan.U:
2204
2205           This variable conditionally defines the "HAS_ISNAN" symbol, which
2206           indicates to the C program that the isnan() routine is available.
2207
2208       "d_isnanl"
2209           From d_isnanl.U:
2210
2211           This variable conditionally defines the "HAS_ISNANL" symbol, which
2212           indicates to the C program that the isnanl() routine is available.
2213
2214       "d_isnormal"
2215           From d_isnormal.U:
2216
2217           This variable conditionally defines the "HAS_ISNORMAL" symbol,
2218           which indicates to the C program that the isnormal() routine is
2219           available.
2220
2221       "d_j0"
2222           From d_j0.U:
2223
2224           This variable conditionally defines the HAS_J0 symbol, which
2225           indicates to the C program that the j0() routine is available.
2226
2227       "d_j0l"
2228           From d_j0.U:
2229
2230           This variable conditionally defines the HAS_J0L symbol, which
2231           indicates to the C program that the j0l() routine is available.
2232
2233       "d_killpg"
2234           From d_killpg.U:
2235
2236           This variable conditionally defines the "HAS_KILLPG" symbol, which
2237           indicates to the C program that the killpg() routine is available
2238           to kill process groups.
2239
2240       "d_lc_monetary_2008"
2241           From d_lc_monetary_2008.U:
2242
2243           This variable conditionally defines HAS_LC_MONETARY_2008 if libc
2244           has the international currency locale rules from "POSIX"
2245           1003.1-2008.
2246
2247       "d_lchown"
2248           From d_lchown.U:
2249
2250           This variable conditionally defines the "HAS_LCHOWN" symbol, which
2251           indicates to the C program that the lchown() routine is available
2252           to operate on a symbolic link (instead of following the link).
2253
2254       "d_ldbl_dig"
2255           From d_ldbl_dig.U:
2256
2257           This variable conditionally defines d_ldbl_dig if this system's
2258           header files provide "LDBL_DIG", which is the number of significant
2259           digits in a long double precision number.
2260
2261       "d_ldexpl"
2262           From d_longdbl.U:
2263
2264           This variable conditionally defines the "HAS_LDEXPL" symbol, which
2265           indicates to the C program that the ldexpl() routine is available.
2266
2267       "d_lgamma"
2268           From d_lgamma.U:
2269
2270           This variable conditionally defines the "HAS_LGAMMA" symbol, which
2271           indicates to the C program that the lgamma() routine is available
2272           for the log gamma function.  See also d_tgamma and d_lgamma_r.
2273
2274       "d_lgamma_r"
2275           From d_lgamma_r.U:
2276
2277           This variable conditionally defines the "HAS_LGAMMA_R" symbol,
2278           which indicates to the C program that the lgamma_r() routine is
2279           available for the log gamma function, without using the global
2280           signgam variable.
2281
2282       "d_libm_lib_version"
2283           From d_libm_lib_version.U:
2284
2285           This variable conditionally defines the "LIBM_LIB_VERSION" symbol,
2286           which indicates to the C program that math.h defines "_LIB_VERSION"
2287           being available in libm
2288
2289       "d_libname_unique"
2290           From so.U:
2291
2292           This variable is defined if the target system insists on unique
2293           basenames for shared library files. This is currently true on
2294           Android, false everywhere else we know of.  Defaults to "undef".
2295
2296       "d_link"
2297           From d_link.U:
2298
2299           This variable conditionally defines "HAS_LINK" if link() is
2300           available to create hard links.
2301
2302       "d_linkat"
2303           From d_fsat.U:
2304
2305           This variable conditionally defines the "HAS_LINKAT" symbol, which
2306           indicates the "POSIX" linkat() function is available.
2307
2308       "d_llrint"
2309           From d_llrint.U:
2310
2311           This variable conditionally defines the "HAS_LLRINT" symbol, which
2312           indicates to the C program that the llrint() routine is available
2313           to return the long long value closest to a double (according to the
2314           current rounding mode).
2315
2316       "d_llrintl"
2317           From d_llrintl.U:
2318
2319           This variable conditionally defines the "HAS_LLRINTL" symbol, which
2320           indicates to the C program that the llrintl() routine is available
2321           to return the long long value closest to a long double (according
2322           to the current rounding mode).
2323
2324       "d_llround"
2325           From d_llround.U:
2326
2327           This variable conditionally defines the "HAS_LLROUND" symbol, which
2328           indicates to the C program that the llround() routine is available
2329           to return the long long value nearest to x.
2330
2331       "d_llroundl"
2332           From d_llroundl.U:
2333
2334           This variable conditionally defines the "HAS_LLROUNDL" symbol,
2335           which indicates to the C program that the llroundl() routine is
2336           available to return the long long value nearest to x away from
2337           zero.
2338
2339       "d_localeconv_l"
2340           From d_localeconv_l.U:
2341
2342           This variable conditionally defines the "HAS_LOCALECONV_L" symbol,
2343           which indicates to the C program that the localeconv_l() routine is
2344           available.
2345
2346       "d_localtime64"
2347           From d_timefuncs64.U:
2348
2349           This variable conditionally defines the HAS_LOCALTIME64 symbol,
2350           which indicates to the C program that the localtime64 () routine is
2351           available.
2352
2353       "d_localtime_r"
2354           From d_localtime_r.U:
2355
2356           This variable conditionally defines the "HAS_LOCALTIME_R" symbol,
2357           which indicates to the C program that the localtime_r() routine is
2358           available.
2359
2360       "d_localtime_r_needs_tzset"
2361           From d_localtime_r.U:
2362
2363           This variable conditionally defines the "LOCALTIME_R_NEEDS_TZSET"
2364           symbol, which makes us call tzset before localtime_r()
2365
2366       "d_locconv"
2367           From d_locconv.U:
2368
2369           This variable conditionally defines "HAS_LOCALECONV" if
2370           localeconv() is available for numeric and monetary formatting
2371           conventions.
2372
2373       "d_lockf"
2374           From d_lockf.U:
2375
2376           This variable conditionally defines "HAS_LOCKF" if lockf() is
2377           available to do file locking.
2378
2379       "d_log1p"
2380           From d_log1p.U:
2381
2382           This variable conditionally defines the HAS_LOG1P symbol, which
2383           indicates to the C program that the logp1() routine is available to
2384           compute log(1 + x) for values of x close to zero.
2385
2386       "d_log2"
2387           From d_log2.U:
2388
2389           This variable conditionally defines the HAS_LOG2 symbol, which
2390           indicates to the C program that the log2() routine is available to
2391           compute log base two.
2392
2393       "d_logb"
2394           From d_logb.U:
2395
2396           This variable conditionally defines the "HAS_LOGB" symbol, which
2397           indicates to the C program that the logb() routine is available to
2398           extract the exponent of x.
2399
2400       "d_long_double_style_ieee"
2401           From d_longdbl.U:
2402
2403           This variable conditionally defines "LONG_DOUBLE_STYLE_IEEE" if the
2404           long double is any of the "IEEE" 754 style long doubles:
2405           "LONG_DOUBLE_STYLE_IEEE_STD", "LONG_DOUBLE_STYLE_IEEE_EXTENDED",
2406           "LONG_DOUBLE_STYLE_IEEE_DOUBLEDOUBLE".
2407
2408       "d_long_double_style_ieee_doubledouble"
2409           From d_longdbl.U:
2410
2411           This variable conditionally defines
2412           "LONG_DOUBLE_STYLE_IEEE_DOUBLEDOUBLE" if the long double is the
2413           128-bit "IEEE" 754 double-double.
2414
2415       "d_long_double_style_ieee_extended"
2416           From d_longdbl.U:
2417
2418           This variable conditionally defines
2419           "LONG_DOUBLE_STYLE_IEEE_EXTENDED" if the long double is the 80-bit
2420           "IEEE" 754 extended precision.  Note that despite the "extended"
2421           this is less than the "std", since thisis an extension of the
2422           double precision.
2423
2424       "d_long_double_style_ieee_std"
2425           From d_longdbl.U:
2426
2427           This variable conditionally defines "LONG_DOUBLE_STYLE_IEEE_STD" if
2428           the long double is the 128-bit "IEEE" 754.
2429
2430       "d_long_double_style_vax"
2431           From d_longdbl.U:
2432
2433           This variable conditionally defines "LONG_DOUBLE_STYLE_VAX" if the
2434           long double is the 128-bit "VAX" format H.
2435
2436       "d_longdbl"
2437           From d_longdbl.U:
2438
2439           This variable conditionally defines "HAS_LONG_DOUBLE" if the long
2440           double type is supported.
2441
2442       "d_longlong"
2443           From d_longlong.U:
2444
2445           This variable conditionally defines "HAS_LONG_LONG" if the long
2446           long type is supported.
2447
2448       "d_lrint"
2449           From d_lrint.U:
2450
2451           This variable conditionally defines the "HAS_LRINT" symbol, which
2452           indicates to the C program that the lrint() routine is available to
2453           return the integral value closest to a double (according to the
2454           current rounding mode).
2455
2456       "d_lrintl"
2457           From d_lrintl.U:
2458
2459           This variable conditionally defines the "HAS_LRINTL" symbol, which
2460           indicates to the C program that the lrintl() routine is available
2461           to return the integral value closest to a long double (according to
2462           the current rounding mode).
2463
2464       "d_lround"
2465           From d_lround.U:
2466
2467           This variable conditionally defines the "HAS_LROUND" symbol, which
2468           indicates to the C program that the lround() routine is available
2469           to return the integral value nearest to x.
2470
2471       "d_lroundl"
2472           From d_lroundl.U:
2473
2474           This variable conditionally defines the "HAS_LROUNDL" symbol, which
2475           indicates to the C program that the lroundl() routine is available
2476           to return the integral value nearest to x away from zero.
2477
2478       "d_lseekproto"
2479           From d_lseekproto.U:
2480
2481           This variable conditionally defines the "HAS_LSEEK_PROTO" symbol,
2482           which indicates to the C program that the system provides a
2483           prototype for the lseek() function.  Otherwise, it is up to the
2484           program to supply one.
2485
2486       "d_lstat"
2487           From d_lstat.U:
2488
2489           This variable conditionally defines "HAS_LSTAT" if lstat() is
2490           available to do file stats on symbolic links.
2491
2492       "d_madvise"
2493           From d_madvise.U:
2494
2495           This variable conditionally defines "HAS_MADVISE" if madvise() is
2496           available to map a file into memory.
2497
2498       "d_malloc_good_size"
2499           From d_malloc_size.U:
2500
2501           This symbol, if defined, indicates that the malloc_good_size
2502           routine is available for use.
2503
2504       "d_malloc_size"
2505           From d_malloc_size.U:
2506
2507           This symbol, if defined, indicates that the malloc_size routine is
2508           available for use.
2509
2510       "d_mblen"
2511           From d_mblen.U:
2512
2513           This variable conditionally defines the "HAS_MBLEN" symbol, which
2514           indicates to the C program that the mblen() routine is available to
2515           find the number of bytes in a multibye character.
2516
2517       "d_mbrlen"
2518           From d_mbrlen.U:
2519
2520           This variable conditionally defines the "HAS_MBRLEN" symbol if the
2521           mbrlen() routine is available to be used to get the length of
2522           multi-byte character strings.
2523
2524       "d_mbrtowc"
2525           From d_mbrtowc.U:
2526
2527           This variable conditionally defines the "HAS_MBRTOWC" symbol if the
2528           mbrtowc() routine is available to be used to convert a multi-byte
2529           character into a wide character.
2530
2531       "d_mbstowcs"
2532           From d_mbstowcs.U:
2533
2534           This variable conditionally defines the "HAS_MBSTOWCS" symbol,
2535           which indicates to the C program that the mbstowcs() routine is
2536           available to convert a multibyte string into a wide character
2537           string.
2538
2539       "d_mbtowc"
2540           From d_mbtowc.U:
2541
2542           This variable conditionally defines the "HAS_MBTOWC" symbol, which
2543           indicates to the C program that the mbtowc() routine is available
2544           to convert multibyte to a wide character.
2545
2546       "d_memmem"
2547           From d_memmem.U:
2548
2549           This variable conditionally defines the "HAS_MEMMEM" symbol, which
2550           indicates to the C program that the memmem() routine is available
2551           to return a pointer to the start of the first occurance of a
2552           substring in a memory area (or "NULL" if not found).
2553
2554       "d_memrchr"
2555           From d_memrchr.U:
2556
2557           This variable conditionally defines the "HAS_MEMRCHR" symbol, which
2558           indicates to the C program that the memrchr() routine is available
2559           to return a pointer to the last occurrence of a byte in a memory
2560           area (or "NULL" if not found).
2561
2562       "d_mkdir"
2563           From d_mkdir.U:
2564
2565           This variable conditionally defines the "HAS_MKDIR" symbol, which
2566           indicates to the C program that the mkdir() routine is available to
2567           create directories..
2568
2569       "d_mkdtemp"
2570           From d_mkdtemp.U:
2571
2572           This variable conditionally defines the "HAS_MKDTEMP" symbol, which
2573           indicates to the C program that the mkdtemp() routine is available
2574           to exclusively create a uniquely named temporary directory.
2575
2576       "d_mkfifo"
2577           From d_mkfifo.U:
2578
2579           This variable conditionally defines the "HAS_MKFIFO" symbol, which
2580           indicates to the C program that the mkfifo() routine is available.
2581
2582       "d_mkostemp"
2583           From d_mkostemp.U:
2584
2585           This variable conditionally defines "HAS_MKOSTEMP" if mkostemp() is
2586           available to exclusively create and open a uniquely named (with a
2587           suffix) temporary file.
2588
2589       "d_mkstemp"
2590           From d_mkstemp.U:
2591
2592           This variable conditionally defines the "HAS_MKSTEMP" symbol, which
2593           indicates to the C program that the mkstemp() routine is available
2594           to exclusively create and open a uniquely named temporary file.
2595
2596       "d_mkstemps"
2597           From d_mkstemps.U:
2598
2599           This variable conditionally defines the "HAS_MKSTEMPS" symbol,
2600           which indicates to the C program that the mkstemps() routine is
2601           available to exclusively create and open a uniquely named (with a
2602           suffix) temporary file.
2603
2604       "d_mktime"
2605           From d_mktime.U:
2606
2607           This variable conditionally defines the "HAS_MKTIME" symbol, which
2608           indicates to the C program that the mktime() routine is available.
2609
2610       "d_mktime64"
2611           From d_timefuncs64.U:
2612
2613           This variable conditionally defines the HAS_MKTIME64 symbol, which
2614           indicates to the C program that the mktime64 () routine is
2615           available.
2616
2617       "d_mmap"
2618           From d_mmap.U:
2619
2620           This variable conditionally defines "HAS_MMAP" if mmap() is
2621           available to map a file into memory.
2622
2623       "d_modfl"
2624           From d_modfl.U:
2625
2626           This variable conditionally defines the "HAS_MODFL" symbol, which
2627           indicates to the C program that the modfl() routine is available.
2628
2629       "d_modflproto"
2630           From d_modfl.U:
2631
2632           This symbol, if defined, indicates that the system provides a
2633           prototype for the modfl() function.  Otherwise, it is up to the
2634           program to supply one.  C99 says it should be long double
2635           modfl(long double, long double *);
2636
2637       "d_mprotect"
2638           From d_mprotect.U:
2639
2640           This variable conditionally defines "HAS_MPROTECT" if mprotect() is
2641           available to modify the access protection of a memory mapped file.
2642
2643       "d_msg"
2644           From d_msg.U:
2645
2646           This variable conditionally defines the "HAS_MSG" symbol, which
2647           indicates that the entire msg*(2) library is present.
2648
2649       "d_msg_ctrunc"
2650           From d_socket.U:
2651
2652           This variable conditionally defines the "HAS_MSG_CTRUNC" symbol,
2653           which indicates that the "MSG_CTRUNC" is available.  #ifdef is not
2654           enough because it may be an enum, glibc has been known to do this.
2655
2656       "d_msg_dontroute"
2657           From d_socket.U:
2658
2659           This variable conditionally defines the "HAS_MSG_DONTROUTE" symbol,
2660           which indicates that the "MSG_DONTROUTE" is available.  #ifdef is
2661           not enough because it may be an enum, glibc has been known to do
2662           this.
2663
2664       "d_msg_oob"
2665           From d_socket.U:
2666
2667           This variable conditionally defines the "HAS_MSG_OOB" symbol, which
2668           indicates that the "MSG_OOB" is available.  #ifdef is not enough
2669           because it may be an enum, glibc has been known to do this.
2670
2671       "d_msg_peek"
2672           From d_socket.U:
2673
2674           This variable conditionally defines the "HAS_MSG_PEEK" symbol,
2675           which indicates that the "MSG_PEEK" is available.  #ifdef is not
2676           enough because it may be an enum, glibc has been known to do this.
2677
2678       "d_msg_proxy"
2679           From d_socket.U:
2680
2681           This variable conditionally defines the "HAS_MSG_PROXY" symbol,
2682           which indicates that the "MSG_PROXY" is available.  #ifdef is not
2683           enough because it may be an enum, glibc has been known to do this.
2684
2685       "d_msgctl"
2686           From d_msgctl.U:
2687
2688           This variable conditionally defines the "HAS_MSGCTL" symbol, which
2689           indicates to the C program that the msgctl() routine is available.
2690
2691       "d_msgget"
2692           From d_msgget.U:
2693
2694           This variable conditionally defines the "HAS_MSGGET" symbol, which
2695           indicates to the C program that the msgget() routine is available.
2696
2697       "d_msghdr_s"
2698           From d_msghdr_s.U:
2699
2700           This variable conditionally defines the "HAS_STRUCT_MSGHDR" symbol,
2701           which indicates that the struct msghdr is supported.
2702
2703       "d_msgrcv"
2704           From d_msgrcv.U:
2705
2706           This variable conditionally defines the "HAS_MSGRCV" symbol, which
2707           indicates to the C program that the msgrcv() routine is available.
2708
2709       "d_msgsnd"
2710           From d_msgsnd.U:
2711
2712           This variable conditionally defines the "HAS_MSGSND" symbol, which
2713           indicates to the C program that the msgsnd() routine is available.
2714
2715       "d_msync"
2716           From d_msync.U:
2717
2718           This variable conditionally defines "HAS_MSYNC" if msync() is
2719           available to synchronize a mapped file.
2720
2721       "d_munmap"
2722           From d_munmap.U:
2723
2724           This variable conditionally defines "HAS_MUNMAP" if munmap() is
2725           available to unmap a region mapped by mmap().
2726
2727       "d_mymalloc"
2728           From mallocsrc.U:
2729
2730           This variable conditionally defines "MYMALLOC" in case other parts
2731           of the source want to take special action if "MYMALLOC" is used.
2732           This may include different sorts of profiling or error detection.
2733
2734       "d_nan"
2735           From d_nan.U:
2736
2737           This variable conditionally defines "HAS_NAN" if nan() is available
2738           to generate NaN.
2739
2740       "d_nanosleep"
2741           From d_nanosleep.U:
2742
2743           This variable conditionally defines "HAS_NANOSLEEP" if nanosleep()
2744           is available to sleep with 1E-9 sec accuracy.
2745
2746       "d_ndbm"
2747           From i_ndbm.U:
2748
2749           This variable conditionally defines the "HAS_NDBM" symbol, which
2750           indicates that both the ndbm.h include file and an appropriate ndbm
2751           library exist.  Consult the different i_*ndbm variables to find out
2752           the actual include location.  Sometimes, a system has the header
2753           file but not the library.  This variable will only be set if the
2754           system has both.
2755
2756       "d_ndbm_h_uses_prototypes"
2757           From i_ndbm.U:
2758
2759           This variable conditionally defines the "NDBM_H_USES_PROTOTYPES"
2760           symbol, which indicates that the ndbm.h include file uses real
2761           "ANSI" C prototypes instead of K&R style function declarations. K&R
2762           style declarations are unsupported in C++, so the include file
2763           requires special handling when using a C++ compiler and this
2764           variable is undefined. Consult the different
2765           d_*ndbm_h_uses_prototypes variables to get the same information for
2766           alternative ndbm.h include files.
2767
2768       "d_nearbyint"
2769           From d_nearbyint.U:
2770
2771           This variable conditionally defines "HAS_NEARBYINT" if nearbyint()
2772           is available to return the integral value closest to (according to
2773           the current rounding mode) to x.
2774
2775       "d_newlocale"
2776           From d_newlocale.U:
2777
2778           This variable conditionally defines the "HAS_NEWLOCALE" symbol,
2779           which indicates to the C program that the newlocale() routine is
2780           available to return a new locale object or modify an existing
2781           locale object.
2782
2783       "d_nextafter"
2784           From d_nextafter.U:
2785
2786           This variable conditionally defines "HAS_NEXTAFTER" if nextafter()
2787           is available to return the next machine representable double from x
2788           in direction y.
2789
2790       "d_nexttoward"
2791           From d_nexttoward.U:
2792
2793           This variable conditionally defines "HAS_NEXTTOWARD" if
2794           nexttoward() is available to return the next machine representable
2795           long double from x in direction y.
2796
2797       "d_nice"
2798           From d_nice.U:
2799
2800           This variable conditionally defines the "HAS_NICE" symbol, which
2801           indicates to the C program that the nice() routine is available.
2802
2803       "d_nl_langinfo"
2804           From d_nl_langinfo.U:
2805
2806           This variable conditionally defines the "HAS_NL_LANGINFO" symbol,
2807           which indicates to the C program that the nl_langinfo() routine is
2808           available.
2809
2810       "d_nv_preserves_uv"
2811           From perlxv.U:
2812
2813           This variable indicates whether a variable of type nvtype can
2814           preserve all the bits a variable of type uvtype.
2815
2816       "d_nv_zero_is_allbits_zero"
2817           From perlxv.U:
2818
2819           This variable indicates whether a variable of type nvtype stores
2820           0.0 in memory as all bits zero.
2821
2822       "d_off64_t"
2823           From d_off64_t.U:
2824
2825           This symbol will be defined if the C compiler supports off64_t.
2826
2827       "d_old_pthread_create_joinable"
2828           From d_pthrattrj.U:
2829
2830           This variable conditionally defines pthread_create_joinable.  undef
2831           if pthread.h defines "PTHREAD_CREATE_JOINABLE".
2832
2833       "d_oldpthreads"
2834           From usethreads.U:
2835
2836           This variable conditionally defines the "OLD_PTHREADS_API" symbol,
2837           and indicates that Perl should be built to use the old draft
2838           "POSIX" threads "API".  This is only potentially meaningful if
2839           usethreads is set.
2840
2841       "d_oldsock"
2842           From d_socket.U:
2843
2844           This variable conditionally defines the "OLDSOCKET" symbol, which
2845           indicates that the "BSD" socket interface is based on 4.1c and not
2846           4.2.
2847
2848       "d_open3"
2849           From d_open3.U:
2850
2851           This variable conditionally defines the HAS_OPEN3 manifest
2852           constant, which indicates to the C program that the 3 argument
2853           version of the open(2) function is available.
2854
2855       "d_openat"
2856           From d_fsat.U:
2857
2858           This variable conditionally defines the "HAS_OPENAT" symbol, which
2859           indicates the "POSIX" openat() function is available.
2860
2861       "d_pathconf"
2862           From d_pathconf.U:
2863
2864           This variable conditionally defines the "HAS_PATHCONF" symbol,
2865           which indicates to the C program that the pathconf() routine is
2866           available to determine file-system related limits and options
2867           associated with a given filename.
2868
2869       "d_pause"
2870           From d_pause.U:
2871
2872           This variable conditionally defines the "HAS_PAUSE" symbol, which
2873           indicates to the C program that the pause() routine is available to
2874           suspend a process until a signal is received.
2875
2876       "d_perl_otherlibdirs"
2877           From otherlibdirs.U:
2878
2879           This variable conditionally defines "PERL_OTHERLIBDIRS", which
2880           contains a colon-separated set of paths for the perl binary to
2881           include in @"INC".  See also otherlibdirs.
2882
2883       "d_phostname"
2884           From d_gethname.U:
2885
2886           This variable conditionally defines the "HAS_PHOSTNAME" symbol,
2887           which contains the shell command which, when fed to popen(), may be
2888           used to derive the host name.
2889
2890       "d_pipe"
2891           From d_pipe.U:
2892
2893           This variable conditionally defines the "HAS_PIPE" symbol, which
2894           indicates to the C program that the pipe() routine is available to
2895           create an inter-process channel.
2896
2897       "d_pipe2"
2898           From d_pipe2.U:
2899
2900           This variable conditionally defines the HAS_PIPE2 symbol, which
2901           indicates to the C program that the pipe2() routine is available to
2902           create an inter-process channel.
2903
2904       "d_poll"
2905           From d_poll.U:
2906
2907           This variable conditionally defines the "HAS_POLL" symbol, which
2908           indicates to the C program that the poll() routine is available to
2909           poll active file descriptors.
2910
2911       "d_portable"
2912           From d_portable.U:
2913
2914           This variable conditionally defines the "PORTABLE" symbol, which
2915           indicates to the C program that it should not assume that it is
2916           running on the machine it was compiled on.
2917
2918       "d_prctl"
2919           From d_prctl.U:
2920
2921           This variable conditionally defines the "HAS_PRCTL" symbol, which
2922           indicates to the C program that the prctl() routine is available.
2923           Note that there are at least two prctl variants: Linux and Irix.
2924           While they are somewhat similar, they are incompatible.
2925
2926       "d_prctl_set_name"
2927           From d_prctl.U:
2928
2929           This variable conditionally defines the "HAS_PRCTL_SET_NAME"
2930           symbol, which indicates to the C program that the prctl() routine
2931           supports the "PR_SET_NAME" option.
2932
2933       "d_PRId64"
2934           From quadfio.U:
2935
2936           This variable conditionally defines the PERL_PRId64 symbol, which
2937           indicates that stdio has a symbol to print 64-bit decimal numbers.
2938
2939       "d_PRIeldbl"
2940           From longdblfio.U:
2941
2942           This variable conditionally defines the PERL_PRIfldbl symbol, which
2943           indicates that stdio has a symbol to print long doubles.
2944
2945       "d_PRIEUldbl"
2946           From longdblfio.U:
2947
2948           This variable conditionally defines the PERL_PRIfldbl symbol, which
2949           indicates that stdio has a symbol to print long doubles.  The "U"
2950           in the name is to separate this from d_PRIeldbl so that even case-
2951           blind systems can see the difference.
2952
2953       "d_PRIfldbl"
2954           From longdblfio.U:
2955
2956           This variable conditionally defines the PERL_PRIfldbl symbol, which
2957           indicates that stdio has a symbol to print long doubles.
2958
2959       "d_PRIFUldbl"
2960           From longdblfio.U:
2961
2962           This variable conditionally defines the PERL_PRIfldbl symbol, which
2963           indicates that stdio has a symbol to print long doubles.  The "U"
2964           in the name is to separate this from d_PRIfldbl so that even case-
2965           blind systems can see the difference.
2966
2967       "d_PRIgldbl"
2968           From longdblfio.U:
2969
2970           This variable conditionally defines the PERL_PRIfldbl symbol, which
2971           indicates that stdio has a symbol to print long doubles.
2972
2973       "d_PRIGUldbl"
2974           From longdblfio.U:
2975
2976           This variable conditionally defines the PERL_PRIfldbl symbol, which
2977           indicates that stdio has a symbol to print long doubles.  The "U"
2978           in the name is to separate this from d_PRIgldbl so that even case-
2979           blind systems can see the difference.
2980
2981       "d_PRIi64"
2982           From quadfio.U:
2983
2984           This variable conditionally defines the PERL_PRIi64 symbol, which
2985           indicates that stdio has a symbol to print 64-bit decimal numbers.
2986
2987       "d_printf_format_null"
2988           From d_attribut.U:
2989
2990           This variable conditionally defines "PRINTF_FORMAT_NULL_OK", which
2991           indicates the C compiler allows printf-like formats to be null.
2992
2993       "d_PRIo64"
2994           From quadfio.U:
2995
2996           This variable conditionally defines the PERL_PRIo64 symbol, which
2997           indicates that stdio has a symbol to print 64-bit octal numbers.
2998
2999       "d_PRIu64"
3000           From quadfio.U:
3001
3002           This variable conditionally defines the PERL_PRIu64 symbol, which
3003           indicates that stdio has a symbol to print 64-bit unsigned decimal
3004           numbers.
3005
3006       "d_PRIx64"
3007           From quadfio.U:
3008
3009           This variable conditionally defines the PERL_PRIx64 symbol, which
3010           indicates that stdio has a symbol to print 64-bit hexadecimal
3011           numbers.
3012
3013       "d_PRIXU64"
3014           From quadfio.U:
3015
3016           This variable conditionally defines the PERL_PRIXU64 symbol, which
3017           indicates that stdio has a symbol to print 64-bit hExADECimAl
3018           numbers.  The "U" in the name is to separate this from d_PRIx64 so
3019           that even case-blind systems can see the difference.
3020
3021       "d_procselfexe"
3022           From d_procselfexe.U:
3023
3024           Defined if $procselfexe is symlink to the absolute pathname of the
3025           executing program.
3026
3027       "d_pseudofork"
3028           From d_vfork.U:
3029
3030           This variable conditionally defines the "HAS_PSEUDOFORK" symbol,
3031           which indicates that an emulation of the fork routine is available.
3032
3033       "d_pthread_atfork"
3034           From d_pthread_atfork.U:
3035
3036           This variable conditionally defines the "HAS_PTHREAD_ATFORK"
3037           symbol, which indicates to the C program that the pthread_atfork()
3038           routine is available.
3039
3040       "d_pthread_attr_setscope"
3041           From d_pthread_attr_ss.U:
3042
3043           This variable conditionally defines "HAS_PTHREAD_ATTR_SETSCOPE" if
3044           pthread_attr_setscope() is available to set the contention scope
3045           attribute of a thread attribute object.
3046
3047       "d_pthread_yield"
3048           From d_pthread_y.U:
3049
3050           This variable conditionally defines the "HAS_PTHREAD_YIELD" symbol
3051           if the pthread_yield routine is available to yield the execution of
3052           the current thread.
3053
3054       "d_ptrdiff_t"
3055           From d_ptrdiff_t.U:
3056
3057           This symbol will be defined if the C compiler supports ptrdiff_t.
3058
3059       "d_pwage"
3060           From i_pwd.U:
3061
3062           This variable conditionally defines "PWAGE", which indicates that
3063           struct passwd contains pw_age.
3064
3065       "d_pwchange"
3066           From i_pwd.U:
3067
3068           This variable conditionally defines "PWCHANGE", which indicates
3069           that struct passwd contains pw_change.
3070
3071       "d_pwclass"
3072           From i_pwd.U:
3073
3074           This variable conditionally defines "PWCLASS", which indicates that
3075           struct passwd contains pw_class.
3076
3077       "d_pwcomment"
3078           From i_pwd.U:
3079
3080           This variable conditionally defines "PWCOMMENT", which indicates
3081           that struct passwd contains pw_comment.
3082
3083       "d_pwexpire"
3084           From i_pwd.U:
3085
3086           This variable conditionally defines "PWEXPIRE", which indicates
3087           that struct passwd contains pw_expire.
3088
3089       "d_pwgecos"
3090           From i_pwd.U:
3091
3092           This variable conditionally defines "PWGECOS", which indicates that
3093           struct passwd contains pw_gecos.
3094
3095       "d_pwpasswd"
3096           From i_pwd.U:
3097
3098           This variable conditionally defines "PWPASSWD", which indicates
3099           that struct passwd contains pw_passwd.
3100
3101       "d_pwquota"
3102           From i_pwd.U:
3103
3104           This variable conditionally defines "PWQUOTA", which indicates that
3105           struct passwd contains pw_quota.
3106
3107       "d_qgcvt"
3108           From d_qgcvt.U:
3109
3110           This variable conditionally defines the "HAS_QGCVT" symbol, which
3111           indicates to the C program that the qgcvt() routine is available.
3112
3113       "d_quad"
3114           From quadtype.U:
3115
3116           This variable, if defined, tells that there's a 64-bit integer
3117           type, quadtype.
3118
3119       "d_querylocale"
3120           From d_newlocale.U:
3121
3122           This variable conditionally defines the "HAS_QUERYLOCALE" symbol,
3123           which indicates to the C program that the querylocale() routine is
3124           available to return the name of the locale for a category mask.
3125
3126       "d_random_r"
3127           From d_random_r.U:
3128
3129           This variable conditionally defines the "HAS_RANDOM_R" symbol,
3130           which indicates to the C program that the random_r() routine is
3131           available.
3132
3133       "d_re_comp"
3134           From d_regcmp.U:
3135
3136           This variable conditionally defines the "HAS_RECOMP" symbol, which
3137           indicates to the C program that the re_comp() routine is available
3138           for regular patern matching (usally on "BSD"). If so, it is likely
3139           that re_exec() exists.
3140
3141       "d_readdir"
3142           From d_readdir.U:
3143
3144           This variable conditionally defines "HAS_READDIR" if readdir() is
3145           available to read directory entries.
3146
3147       "d_readdir64_r"
3148           From d_readdir64_r.U:
3149
3150           This variable conditionally defines the HAS_READDIR64_R symbol,
3151           which indicates to the C program that the readdir64_r() routine is
3152           available.
3153
3154       "d_readdir_r"
3155           From d_readdir_r.U:
3156
3157           This variable conditionally defines the "HAS_READDIR_R" symbol,
3158           which indicates to the C program that the readdir_r() routine is
3159           available.
3160
3161       "d_readlink"
3162           From d_readlink.U:
3163
3164           This variable conditionally defines the "HAS_READLINK" symbol,
3165           which indicates to the C program that the readlink() routine is
3166           available to read the value of a symbolic link.
3167
3168       "d_readv"
3169           From d_readv.U:
3170
3171           This variable conditionally defines the "HAS_READV" symbol, which
3172           indicates to the C program that the readv() routine is available.
3173
3174       "d_recvmsg"
3175           From d_recvmsg.U:
3176
3177           This variable conditionally defines the "HAS_RECVMSG" symbol, which
3178           indicates to the C program that the recvmsg() routine is available.
3179
3180       "d_regcmp"
3181           From d_regcmp.U:
3182
3183           This variable conditionally defines the "HAS_REGCMP" symbol, which
3184           indicates to the C program that the regcmp() routine is available
3185           for regular patern matching (usally on System V).
3186
3187       "d_regcomp"
3188           From d_regcmp.U:
3189
3190           This variable conditionally defines the "HAS_REGCOMP" symbol, which
3191           indicates to the C program that the regcomp() routine is available
3192           for regular patern matching (usally on POSIX.2 conforming systems).
3193
3194       "d_remainder"
3195           From d_remainder.U:
3196
3197           This variable conditionally defines the "HAS_REMAINDER" symbol,
3198           which indicates to the C program that the remainder() routine is
3199           available.
3200
3201       "d_remquo"
3202           From d_remquo.U:
3203
3204           This variable conditionally defines the "HAS_REMQUO" symbol, which
3205           indicates to the C program that the remquo() routine is available.
3206
3207       "d_rename"
3208           From d_rename.U:
3209
3210           This variable conditionally defines the "HAS_RENAME" symbol, which
3211           indicates to the C program that the rename() routine is available
3212           to rename files.
3213
3214       "d_renameat"
3215           From d_fsat.U:
3216
3217           This variable conditionally defines the "HAS_RENAMEAT" symbol,
3218           which indicates the "POSIX" renameat() function is available.
3219
3220       "d_rewinddir"
3221           From d_readdir.U:
3222
3223           This variable conditionally defines "HAS_REWINDDIR" if rewinddir()
3224           is available.
3225
3226       "d_rint"
3227           From d_rint.U:
3228
3229           This variable conditionally defines the "HAS_RINT" symbol, which
3230           indicates to the C program that the rint() routine is available.
3231
3232       "d_rmdir"
3233           From d_rmdir.U:
3234
3235           This variable conditionally defines "HAS_RMDIR" if rmdir() is
3236           available to remove directories.
3237
3238       "d_round"
3239           From d_round.U:
3240
3241           This variable conditionally defines the "HAS_ROUND" symbol, which
3242           indicates to the C program that the round() routine is available.
3243
3244       "d_sbrkproto"
3245           From d_sbrkproto.U:
3246
3247           This variable conditionally defines the "HAS_SBRK_PROTO" symbol,
3248           which indicates to the C program that the system provides a
3249           prototype for the sbrk() function.  Otherwise, it is up to the
3250           program to supply one.
3251
3252       "d_scalbn"
3253           From d_scalbn.U:
3254
3255           This variable conditionally defines the "HAS_SCALBN" symbol, which
3256           indicates to the C program that the scalbn() routine is available.
3257
3258       "d_scalbnl"
3259           From d_scalbnl.U:
3260
3261           This variable conditionally defines the "HAS_SCALBNL" symbol, which
3262           indicates to the C program that the scalbnl() routine is available.
3263           If ilogbl is also present we can emulate frexpl.
3264
3265       "d_sched_yield"
3266           From d_pthread_y.U:
3267
3268           This variable conditionally defines the "HAS_SCHED_YIELD" symbol if
3269           the sched_yield routine is available to yield the execution of the
3270           current thread.
3271
3272       "d_scm_rights"
3273           From d_socket.U:
3274
3275           This variable conditionally defines the "HAS_SCM_RIGHTS" symbol,
3276           which indicates that the "SCM_RIGHTS" is available.  #ifdef is not
3277           enough because it may be an enum, glibc has been known to do this.
3278
3279       "d_SCNfldbl"
3280           From longdblfio.U:
3281
3282           This variable conditionally defines the PERL_PRIfldbl symbol, which
3283           indicates that stdio has a symbol to scan long doubles.
3284
3285       "d_seekdir"
3286           From d_readdir.U:
3287
3288           This variable conditionally defines "HAS_SEEKDIR" if seekdir() is
3289           available.
3290
3291       "d_select"
3292           From d_select.U:
3293
3294           This variable conditionally defines "HAS_SELECT" if select() is
3295           available to select active file descriptors. A <sys/time.h>
3296           inclusion may be necessary for the timeout field.
3297
3298       "d_sem"
3299           From d_sem.U:
3300
3301           This variable conditionally defines the "HAS_SEM" symbol, which
3302           indicates that the entire sem*(2) library is present.
3303
3304       "d_semctl"
3305           From d_semctl.U:
3306
3307           This variable conditionally defines the "HAS_SEMCTL" symbol, which
3308           indicates to the C program that the semctl() routine is available.
3309
3310       "d_semctl_semid_ds"
3311           From d_union_semun.U:
3312
3313           This variable conditionally defines "USE_SEMCTL_SEMID_DS", which
3314           indicates that struct semid_ds * is to be used for semctl
3315           "IPC_STAT".
3316
3317       "d_semctl_semun"
3318           From d_union_semun.U:
3319
3320           This variable conditionally defines "USE_SEMCTL_SEMUN", which
3321           indicates that union semun is to be used for semctl "IPC_STAT".
3322
3323       "d_semget"
3324           From d_semget.U:
3325
3326           This variable conditionally defines the "HAS_SEMGET" symbol, which
3327           indicates to the C program that the semget() routine is available.
3328
3329       "d_semop"
3330           From d_semop.U:
3331
3332           This variable conditionally defines the "HAS_SEMOP" symbol, which
3333           indicates to the C program that the semop() routine is available.
3334
3335       "d_sendmsg"
3336           From d_sendmsg.U:
3337
3338           This variable conditionally defines the "HAS_SENDMSG" symbol, which
3339           indicates to the C program that the sendmsg() routine is available.
3340
3341       "d_setegid"
3342           From d_setegid.U:
3343
3344           This variable conditionally defines the "HAS_SETEGID" symbol, which
3345           indicates to the C program that the setegid() routine is available
3346           to change the effective gid of the current program.
3347
3348       "d_seteuid"
3349           From d_seteuid.U:
3350
3351           This variable conditionally defines the "HAS_SETEUID" symbol, which
3352           indicates to the C program that the seteuid() routine is available
3353           to change the effective uid of the current program.
3354
3355       "d_setgrent"
3356           From d_setgrent.U:
3357
3358           This variable conditionally defines the "HAS_SETGRENT" symbol,
3359           which indicates to the C program that the setgrent() routine is
3360           available for initializing sequential access to the group database.
3361
3362       "d_setgrent_r"
3363           From d_setgrent_r.U:
3364
3365           This variable conditionally defines the "HAS_SETGRENT_R" symbol,
3366           which indicates to the C program that the setgrent_r() routine is
3367           available.
3368
3369       "d_setgrps"
3370           From d_setgrps.U:
3371
3372           This variable conditionally defines the "HAS_SETGROUPS" symbol,
3373           which indicates to the C program that the setgroups() routine is
3374           available to set the list of process groups.
3375
3376       "d_sethent"
3377           From d_sethent.U:
3378
3379           This variable conditionally defines "HAS_SETHOSTENT" if
3380           sethostent() is available.
3381
3382       "d_sethostent_r"
3383           From d_sethostent_r.U:
3384
3385           This variable conditionally defines the "HAS_SETHOSTENT_R" symbol,
3386           which indicates to the C program that the sethostent_r() routine is
3387           available.
3388
3389       "d_setitimer"
3390           From d_setitimer.U:
3391
3392           This variable conditionally defines the "HAS_SETITIMER" symbol,
3393           which indicates to the C program that the setitimer() routine is
3394           available.
3395
3396       "d_setlinebuf"
3397           From d_setlnbuf.U:
3398
3399           This variable conditionally defines the "HAS_SETLINEBUF" symbol,
3400           which indicates to the C program that the setlinebuf() routine is
3401           available to change stderr or stdout from block-buffered or
3402           unbuffered to a line-buffered mode.
3403
3404       "d_setlocale"
3405           From d_setlocale.U:
3406
3407           This variable conditionally defines "HAS_SETLOCALE" if setlocale()
3408           is available to handle locale-specific ctype implementations.
3409
3410       "d_setlocale_accepts_any_locale_name"
3411           From d_setlocale.U:
3412
3413           This variable conditionally defines
3414           "SETLOCALE_ACCEPTS_ANY_LOCALE_NAME" if setlocale() accepts any
3415           locale name.
3416
3417       "d_setlocale_r"
3418           From d_setlocale_r.U:
3419
3420           This variable conditionally defines the "HAS_SETLOCALE_R" symbol,
3421           which indicates to the C program that the setlocale_r() routine is
3422           available.
3423
3424       "d_setnent"
3425           From d_setnent.U:
3426
3427           This variable conditionally defines "HAS_SETNETENT" if setnetent()
3428           is available.
3429
3430       "d_setnetent_r"
3431           From d_setnetent_r.U:
3432
3433           This variable conditionally defines the "HAS_SETNETENT_R" symbol,
3434           which indicates to the C program that the setnetent_r() routine is
3435           available.
3436
3437       "d_setpent"
3438           From d_setpent.U:
3439
3440           This variable conditionally defines "HAS_SETPROTOENT" if
3441           setprotoent() is available.
3442
3443       "d_setpgid"
3444           From d_setpgid.U:
3445
3446           This variable conditionally defines the "HAS_SETPGID" symbol if the
3447           setpgid(pid, gpid) function is available to set process group "ID".
3448
3449       "d_setpgrp"
3450           From d_setpgrp.U:
3451
3452           This variable conditionally defines "HAS_SETPGRP" if setpgrp() is
3453           available to set the current process group.
3454
3455       "d_setpgrp2"
3456           From d_setpgrp2.U:
3457
3458           This variable conditionally defines the HAS_SETPGRP2 symbol, which
3459           indicates to the C program that the setpgrp2() (as in DG/"UX")
3460           routine is available to set the current process group.
3461
3462       "d_setprior"
3463           From d_setprior.U:
3464
3465           This variable conditionally defines "HAS_SETPRIORITY" if
3466           setpriority() is available to set a process's priority.
3467
3468       "d_setproctitle"
3469           From d_setproctitle.U:
3470
3471           This variable conditionally defines the "HAS_SETPROCTITLE" symbol,
3472           which indicates to the C program that the setproctitle() routine is
3473           available.
3474
3475       "d_setprotoent_r"
3476           From d_setprotoent_r.U:
3477
3478           This variable conditionally defines the "HAS_SETPROTOENT_R" symbol,
3479           which indicates to the C program that the setprotoent_r() routine
3480           is available.
3481
3482       "d_setpwent"
3483           From d_setpwent.U:
3484
3485           This variable conditionally defines the "HAS_SETPWENT" symbol,
3486           which indicates to the C program that the setpwent() routine is
3487           available for initializing sequential access to the passwd
3488           database.
3489
3490       "d_setpwent_r"
3491           From d_setpwent_r.U:
3492
3493           This variable conditionally defines the "HAS_SETPWENT_R" symbol,
3494           which indicates to the C program that the setpwent_r() routine is
3495           available.
3496
3497       "d_setregid"
3498           From d_setregid.U:
3499
3500           This variable conditionally defines "HAS_SETREGID" if setregid() is
3501           available to change the real and effective gid of the current
3502           process.
3503
3504       "d_setresgid"
3505           From d_setregid.U:
3506
3507           This variable conditionally defines "HAS_SETRESGID" if setresgid()
3508           is available to change the real, effective and saved gid of the
3509           current process.
3510
3511       "d_setresuid"
3512           From d_setreuid.U:
3513
3514           This variable conditionally defines "HAS_SETREUID" if setresuid()
3515           is available to change the real, effective and saved uid of the
3516           current process.
3517
3518       "d_setreuid"
3519           From d_setreuid.U:
3520
3521           This variable conditionally defines "HAS_SETREUID" if setreuid() is
3522           available to change the real and effective uid of the current
3523           process.
3524
3525       "d_setrgid"
3526           From d_setrgid.U:
3527
3528           This variable conditionally defines the "HAS_SETRGID" symbol, which
3529           indicates to the C program that the setrgid() routine is available
3530           to change the real gid of the current program.
3531
3532       "d_setruid"
3533           From d_setruid.U:
3534
3535           This variable conditionally defines the "HAS_SETRUID" symbol, which
3536           indicates to the C program that the setruid() routine is available
3537           to change the real uid of the current program.
3538
3539       "d_setsent"
3540           From d_setsent.U:
3541
3542           This variable conditionally defines "HAS_SETSERVENT" if
3543           setservent() is available.
3544
3545       "d_setservent_r"
3546           From d_setservent_r.U:
3547
3548           This variable conditionally defines the "HAS_SETSERVENT_R" symbol,
3549           which indicates to the C program that the setservent_r() routine is
3550           available.
3551
3552       "d_setsid"
3553           From d_setsid.U:
3554
3555           This variable conditionally defines "HAS_SETSID" if setsid() is
3556           available to set the process group "ID".
3557
3558       "d_setvbuf"
3559           From d_setvbuf.U:
3560
3561           This variable conditionally defines the "HAS_SETVBUF" symbol, which
3562           indicates to the C program that the setvbuf() routine is available
3563           to change buffering on an open stdio stream.
3564
3565       "d_shm"
3566           From d_shm.U:
3567
3568           This variable conditionally defines the "HAS_SHM" symbol, which
3569           indicates that the entire shm*(2) library is present.
3570
3571       "d_shmat"
3572           From d_shmat.U:
3573
3574           This variable conditionally defines the "HAS_SHMAT" symbol, which
3575           indicates to the C program that the shmat() routine is available.
3576
3577       "d_shmatprototype"
3578           From d_shmat.U:
3579
3580           This variable conditionally defines the "HAS_SHMAT_PROTOTYPE"
3581           symbol, which indicates that sys/shm.h has a prototype for shmat.
3582
3583       "d_shmctl"
3584           From d_shmctl.U:
3585
3586           This variable conditionally defines the "HAS_SHMCTL" symbol, which
3587           indicates to the C program that the shmctl() routine is available.
3588
3589       "d_shmdt"
3590           From d_shmdt.U:
3591
3592           This variable conditionally defines the "HAS_SHMDT" symbol, which
3593           indicates to the C program that the shmdt() routine is available.
3594
3595       "d_shmget"
3596           From d_shmget.U:
3597
3598           This variable conditionally defines the "HAS_SHMGET" symbol, which
3599           indicates to the C program that the shmget() routine is available.
3600
3601       "d_sigaction"
3602           From d_sigaction.U:
3603
3604           This variable conditionally defines the "HAS_SIGACTION" symbol,
3605           which indicates that the Vr4 sigaction() routine is available.
3606
3607       "d_siginfo_si_addr"
3608           From d_siginfo_si.U:
3609
3610           This variable conditionally defines the "HAS_SIGINFO_SI_ADDR"
3611           symbol, which indicates that the siginfo_t struct has the si_addr
3612           member.
3613
3614       "d_siginfo_si_band"
3615           From d_siginfo_si.U:
3616
3617           This variable conditionally defines the "HAS_SIGINFO_SI_BAND"
3618           symbol, which indicates that the siginfo_t struct has the si_band
3619           member.
3620
3621       "d_siginfo_si_errno"
3622           From d_siginfo_si.U:
3623
3624           This variable conditionally defines the "HAS_SIGINFO_SI_ERRNO"
3625           symbol, which indicates that the siginfo_t struct has the si_errno
3626           member.
3627
3628       "d_siginfo_si_fd"
3629           From d_siginfo_si.U:
3630
3631           This variable conditionally defines the "HAS_SIGINFO_SI_FD" symbol,
3632           which indicates that the siginfo_t struct has the si_fd member.
3633
3634       "d_siginfo_si_pid"
3635           From d_siginfo_si.U:
3636
3637           This variable conditionally defines the "HAS_SIGINFO_SI_PID"
3638           symbol, which indicates that the siginfo_t struct has the si_pid
3639           member.
3640
3641       "d_siginfo_si_status"
3642           From d_siginfo_si.U:
3643
3644           This variable conditionally defines the "HAS_SIGINFO_SI_STATUS"
3645           symbol, which indicates that the siginfo_t struct has the si_status
3646           member.
3647
3648       "d_siginfo_si_uid"
3649           From d_siginfo_si.U:
3650
3651           This variable conditionally defines the "HAS_SIGINFO_SI_UID"
3652           symbol, which indicates that the siginfo_t struct has the si_uid
3653           member.
3654
3655       "d_siginfo_si_value"
3656           From d_siginfo_si.U:
3657
3658           This variable conditionally defines the "HAS_SIGINFO_SI_VALUE"
3659           symbol, which indicates that the siginfo_t struct has the si_value
3660           member.
3661
3662       "d_signbit"
3663           From d_signbit.U:
3664
3665           This variable conditionally defines the "HAS_SIGNBIT" symbol, which
3666           indicates to the C program that the signbit() routine is available
3667           and safe to use with perl's intern "NV" type.
3668
3669       "d_sigprocmask"
3670           From d_sigprocmask.U:
3671
3672           This variable conditionally defines "HAS_SIGPROCMASK" if
3673           sigprocmask() is available to examine or change the signal mask of
3674           the calling process.
3675
3676       "d_sigsetjmp"
3677           From d_sigsetjmp.U:
3678
3679           This variable conditionally defines the "HAS_SIGSETJMP" symbol,
3680           which indicates that the sigsetjmp() routine is available to call
3681           setjmp() and optionally save the process's signal mask.
3682
3683       "d_sin6_scope_id"
3684           From d_socket.U:
3685
3686           This variable conditionally defines the HAS_SIN6_SCOPE_ID symbol,
3687           which indicates that a struct sockaddr_in6 structure has the
3688           sin6_scope_id member.
3689
3690       "d_sitearch"
3691           From sitearch.U:
3692
3693           This variable conditionally defines "SITEARCH" to hold the pathname
3694           of architecture-dependent library files for $package.  If $sitearch
3695           is the same as $archlib, then this is set to undef.
3696
3697       "d_snprintf"
3698           From d_snprintf.U:
3699
3700           This variable conditionally defines the "HAS_SNPRINTF" symbol,
3701           which indicates to the C program that the snprintf () library
3702           function is available.
3703
3704       "d_sockaddr_in6"
3705           From d_socket.U:
3706
3707           This variable conditionally defines the HAS_SOCKADDR_IN6 symbol,
3708           which indicates the availability of a struct sockaddr_in6.
3709
3710       "d_sockaddr_sa_len"
3711           From d_socket.U:
3712
3713           This variable conditionally defines the "HAS_SOCKADDR_SA_LEN"
3714           symbol, which indicates that a struct sockaddr structure has the
3715           sa_len member.
3716
3717       "d_sockatmark"
3718           From d_sockatmark.U:
3719
3720           This variable conditionally defines the "HAS_SOCKATMARK" symbol,
3721           which indicates to the C program that the sockatmark() routine is
3722           available.
3723
3724       "d_sockatmarkproto"
3725           From d_sockatmarkproto.U:
3726
3727           This variable conditionally defines the "HAS_SOCKATMARK_PROTO"
3728           symbol, which indicates to the C program that the system provides a
3729           prototype for the sockatmark() function.  Otherwise, it is up to
3730           the program to supply one.
3731
3732       "d_socket"
3733           From d_socket.U:
3734
3735           This variable conditionally defines "HAS_SOCKET", which indicates
3736           that the "BSD" socket interface is supported.
3737
3738       "d_socklen_t"
3739           From d_socklen_t.U:
3740
3741           This symbol will be defined if the C compiler supports socklen_t.
3742
3743       "d_sockpair"
3744           From d_socket.U:
3745
3746           This variable conditionally defines the "HAS_SOCKETPAIR" symbol,
3747           which indicates that the "BSD" socketpair() is supported.
3748
3749       "d_socks5_init"
3750           From d_socks5_init.U:
3751
3752           This variable conditionally defines the HAS_SOCKS5_INIT symbol,
3753           which indicates to the C program that the socks5_init() routine is
3754           available.
3755
3756       "d_sqrtl"
3757           From d_sqrtl.U:
3758
3759           This variable conditionally defines the "HAS_SQRTL" symbol, which
3760           indicates to the C program that the sqrtl() routine is available.
3761
3762       "d_srand48_r"
3763           From d_srand48_r.U:
3764
3765           This variable conditionally defines the HAS_SRAND48_R symbol, which
3766           indicates to the C program that the srand48_r() routine is
3767           available.
3768
3769       "d_srandom_r"
3770           From d_srandom_r.U:
3771
3772           This variable conditionally defines the "HAS_SRANDOM_R" symbol,
3773           which indicates to the C program that the srandom_r() routine is
3774           available.
3775
3776       "d_sresgproto"
3777           From d_sresgproto.U:
3778
3779           This variable conditionally defines the "HAS_SETRESGID_PROTO"
3780           symbol, which indicates to the C program that the system provides a
3781           prototype for the setresgid() function.  Otherwise, it is up to the
3782           program to supply one.
3783
3784       "d_sresuproto"
3785           From d_sresuproto.U:
3786
3787           This variable conditionally defines the "HAS_SETRESUID_PROTO"
3788           symbol, which indicates to the C program that the system provides a
3789           prototype for the setresuid() function.  Otherwise, it is up to the
3790           program to supply one.
3791
3792       "d_stat"
3793           From d_stat.U:
3794
3795           This variable conditionally defines "HAS_STAT" if stat() is
3796           available to get file status.
3797
3798       "d_statblks"
3799           From d_statblks.U:
3800
3801           This variable conditionally defines "USE_STAT_BLOCKS" if this
3802           system has a stat structure declaring st_blksize and st_blocks.
3803
3804       "d_statfs_f_flags"
3805           From d_statfs_f_flags.U:
3806
3807           This variable conditionally defines the "HAS_STRUCT_STATFS_F_FLAGS"
3808           symbol, which indicates to struct statfs from has f_flags member.
3809           This kind of struct statfs is coming from sys/mount.h ("BSD"), not
3810           from sys/statfs.h ("SYSV").
3811
3812       "d_statfs_s"
3813           From d_statfs_s.U:
3814
3815           This variable conditionally defines the "HAS_STRUCT_STATFS" symbol,
3816           which indicates that the struct statfs is supported.
3817
3818       "d_static_inline"
3819           From d_static_inline.U:
3820
3821           This variable conditionally defines the "HAS_STATIC_INLINE" symbol,
3822           which indicates that the C compiler supports C99-style static
3823           inline.  That is, the function can't be called from another
3824           translation unit.
3825
3826       "d_statvfs"
3827           From d_statvfs.U:
3828
3829           This variable conditionally defines the "HAS_STATVFS" symbol, which
3830           indicates to the C program that the statvfs() routine is available.
3831
3832       "d_stdio_cnt_lval"
3833           From d_stdstdio.U:
3834
3835           This variable conditionally defines "STDIO_CNT_LVALUE" if the
3836           "FILE_cnt" macro can be used as an lvalue.
3837
3838       "d_stdio_ptr_lval"
3839           From d_stdstdio.U:
3840
3841           This variable conditionally defines "STDIO_PTR_LVALUE" if the
3842           "FILE_ptr" macro can be used as an lvalue.
3843
3844       "d_stdio_ptr_lval_nochange_cnt"
3845           From d_stdstdio.U:
3846
3847           This symbol is defined if using the "FILE_ptr" macro as an lvalue
3848           to increase the pointer by n leaves File_cnt(fp) unchanged.
3849
3850       "d_stdio_ptr_lval_sets_cnt"
3851           From d_stdstdio.U:
3852
3853           This symbol is defined if using the "FILE_ptr" macro as an lvalue
3854           to increase the pointer by n has the side effect of decreasing the
3855           value of File_cnt(fp) by n.
3856
3857       "d_stdio_stream_array"
3858           From stdio_streams.U:
3859
3860           This variable tells whether there is an array holding the stdio
3861           streams.
3862
3863       "d_stdiobase"
3864           From d_stdstdio.U:
3865
3866           This variable conditionally defines "USE_STDIO_BASE" if this system
3867           has a "FILE" structure declaring a usable _base field (or
3868           equivalent) in stdio.h.
3869
3870       "d_stdstdio"
3871           From d_stdstdio.U:
3872
3873           This variable conditionally defines "USE_STDIO_PTR" if this system
3874           has a "FILE" structure declaring usable _ptr and _cnt fields (or
3875           equivalent) in stdio.h.
3876
3877       "d_strcoll"
3878           From d_strcoll.U:
3879
3880           This variable conditionally defines "HAS_STRCOLL" if strcoll() is
3881           available to compare strings using collating information.
3882
3883       "d_strerror_l"
3884           From d_strerror_l.U:
3885
3886           This variable conditionally defines the "HAS_STRERROR_L" symbol,
3887           which indicates to the C program that the strerror_l() routine is
3888           available to return the error message for a given errno value in a
3889           particular locale (identified by a locale_t object).
3890
3891       "d_strerror_r"
3892           From d_strerror_r.U:
3893
3894           This variable conditionally defines the "HAS_STRERROR_R" symbol,
3895           which indicates to the C program that the strerror_r() routine is
3896           available.
3897
3898       "d_strftime"
3899           From d_strftime.U:
3900
3901           This variable conditionally defines the "HAS_STRFTIME" symbol,
3902           which indicates to the C program that the strftime() routine is
3903           available.
3904
3905       "d_strlcat"
3906           From d_strlcat.U:
3907
3908           This variable conditionally defines the "HAS_STRLCAT" symbol, which
3909           indicates to the C program that the strlcat () routine is
3910           available.
3911
3912       "d_strlcpy"
3913           From d_strlcpy.U:
3914
3915           This variable conditionally defines the "HAS_STRLCPY" symbol, which
3916           indicates to the C program that the strlcpy () routine is
3917           available.
3918
3919       "d_strnlen"
3920           From d_strnlen.U:
3921
3922           This variable conditionally defines the "HAS_STRNLEN" symbol, which
3923           indicates to the C program that the strnlen () routine is
3924           available.
3925
3926       "d_strtod"
3927           From d_strtod.U:
3928
3929           This variable conditionally defines the "HAS_STRTOD" symbol, which
3930           indicates to the C program that the strtod() routine is available
3931           to provide better numeric string conversion than atof().
3932
3933       "d_strtod_l"
3934           From d_strtod_l.U:
3935
3936           This variable conditionally defines the "HAS_STRTOD_L" symbol,
3937           which indicates to the C program that the strtod_l() routine is
3938           available.
3939
3940       "d_strtol"
3941           From d_strtol.U:
3942
3943           This variable conditionally defines the "HAS_STRTOL" symbol, which
3944           indicates to the C program that the strtol() routine is available
3945           to provide better numeric string conversion than atoi() and
3946           friends.
3947
3948       "d_strtold"
3949           From d_strtold.U:
3950
3951           This variable conditionally defines the "HAS_STRTOLD" symbol, which
3952           indicates to the C program that the strtold() routine is available.
3953
3954       "d_strtold_l"
3955           From d_strtold_l.U:
3956
3957           This variable conditionally defines the "HAS_STRTOLD_L" symbol,
3958           which indicates to the C program that the strtold_l() routine is
3959           available.
3960
3961       "d_strtoll"
3962           From d_strtoll.U:
3963
3964           This variable conditionally defines the "HAS_STRTOLL" symbol, which
3965           indicates to the C program that the strtoll() routine is available.
3966
3967       "d_strtoq"
3968           From d_strtoq.U:
3969
3970           This variable conditionally defines the "HAS_STRTOQ" symbol, which
3971           indicates to the C program that the strtoq() routine is available.
3972
3973       "d_strtoul"
3974           From d_strtoul.U:
3975
3976           This variable conditionally defines the "HAS_STRTOUL" symbol, which
3977           indicates to the C program that the strtoul() routine is available
3978           to provide conversion of strings to unsigned long.
3979
3980       "d_strtoull"
3981           From d_strtoull.U:
3982
3983           This variable conditionally defines the "HAS_STRTOULL" symbol,
3984           which indicates to the C program that the strtoull() routine is
3985           available.
3986
3987       "d_strtouq"
3988           From d_strtouq.U:
3989
3990           This variable conditionally defines the "HAS_STRTOUQ" symbol, which
3991           indicates to the C program that the strtouq() routine is available.
3992
3993       "d_strxfrm"
3994           From d_strxfrm.U:
3995
3996           This variable conditionally defines "HAS_STRXFRM" if strxfrm() is
3997           available to transform strings.
3998
3999       "d_suidsafe"
4000           From d_dosuid.U:
4001
4002           This variable conditionally defines "SETUID_SCRIPTS_ARE_SECURE_NOW"
4003           if setuid scripts can be secure.  This test looks in /dev/fd/.
4004
4005       "d_symlink"
4006           From d_symlink.U:
4007
4008           This variable conditionally defines the "HAS_SYMLINK" symbol, which
4009           indicates to the C program that the symlink() routine is available
4010           to create symbolic links.
4011
4012       "d_syscall"
4013           From d_syscall.U:
4014
4015           This variable conditionally defines "HAS_SYSCALL" if syscall() is
4016           available call arbitrary system calls.
4017
4018       "d_syscallproto"
4019           From d_syscallproto.U:
4020
4021           This variable conditionally defines the "HAS_SYSCALL_PROTO" symbol,
4022           which indicates to the C program that the system provides a
4023           prototype for the syscall() function.  Otherwise, it is up to the
4024           program to supply one.
4025
4026       "d_sysconf"
4027           From d_sysconf.U:
4028
4029           This variable conditionally defines the "HAS_SYSCONF" symbol, which
4030           indicates to the C program that the sysconf() routine is available
4031           to determine system related limits and options.
4032
4033       "d_sysernlst"
4034           From d_strerror.U:
4035
4036           This variable conditionally defines "HAS_SYS_ERRNOLIST" if
4037           sys_errnolist[] is available to translate error numbers to the
4038           symbolic name.
4039
4040       "d_syserrlst"
4041           From d_strerror.U:
4042
4043           This variable conditionally defines "HAS_SYS_ERRLIST" if
4044           sys_errlist[] is available to translate error numbers to strings.
4045
4046       "d_system"
4047           From d_system.U:
4048
4049           This variable conditionally defines "HAS_SYSTEM" if system() is
4050           available to issue a shell command.
4051
4052       "d_tcgetpgrp"
4053           From d_tcgtpgrp.U:
4054
4055           This variable conditionally defines the "HAS_TCGETPGRP" symbol,
4056           which indicates to the C program that the tcgetpgrp() routine is
4057           available.  to get foreground process group "ID".
4058
4059       "d_tcsetpgrp"
4060           From d_tcstpgrp.U:
4061
4062           This variable conditionally defines the "HAS_TCSETPGRP" symbol,
4063           which indicates to the C program that the tcsetpgrp() routine is
4064           available to set foreground process group "ID".
4065
4066       "d_telldir"
4067           From d_readdir.U:
4068
4069           This variable conditionally defines "HAS_TELLDIR" if telldir() is
4070           available.
4071
4072       "d_telldirproto"
4073           From d_telldirproto.U:
4074
4075           This variable conditionally defines the "HAS_TELLDIR_PROTO" symbol,
4076           which indicates to the C program that the system provides a
4077           prototype for the telldir() function.  Otherwise, it is up to the
4078           program to supply one.
4079
4080       "d_tgamma"
4081           From d_tgamma.U:
4082
4083           This variable conditionally defines the "HAS_TGAMMA" symbol, which
4084           indicates to the C program that the tgamma() routine is available
4085           for the gamma function.  See also d_lgamma.
4086
4087       "d_thread_safe_nl_langinfo_l"
4088           From d_nl_langinfo_l.U:
4089
4090           This variable contains the eventual value of the
4091           "HAS_THREAD_SAFE_NL_LANGINFO_L" symbol, which indicates if the
4092           nl_langinfo_l() function exists and is thread-safe.
4093
4094       "d_time"
4095           From d_time.U:
4096
4097           This variable conditionally defines the "HAS_TIME" symbol, which
4098           indicates that the time() routine exists.  The time() routine is
4099           normally provided on "UNIX" systems.
4100
4101       "d_timegm"
4102           From d_timegm.U:
4103
4104           This variable conditionally defines the "HAS_TIMEGM" symbol, which
4105           indicates to the C program that the timegm () routine is available.
4106
4107       "d_times"
4108           From d_times.U:
4109
4110           This variable conditionally defines the "HAS_TIMES" symbol, which
4111           indicates that the times() routine exists.  The times() routine is
4112           normally provided on "UNIX" systems. You may have to include
4113           <sys/times.h>.
4114
4115       "d_tm_tm_gmtoff"
4116           From i_time.U:
4117
4118           This variable conditionally defines "HAS_TM_TM_GMTOFF", which
4119           indicates indicates to the C program that the struct tm has the
4120           tm_gmtoff field.
4121
4122       "d_tm_tm_zone"
4123           From i_time.U:
4124
4125           This variable conditionally defines "HAS_TM_TM_ZONE", which
4126           indicates indicates to the C program that the struct tm has the
4127           tm_zone field.
4128
4129       "d_tmpnam_r"
4130           From d_tmpnam_r.U:
4131
4132           This variable conditionally defines the "HAS_TMPNAM_R" symbol,
4133           which indicates to the C program that the tmpnam_r() routine is
4134           available.
4135
4136       "d_towlower"
4137           From d_towlower.U:
4138
4139           This variable conditionally defines the "HAS_TOWLOWER" symbol,
4140           which indicates to the C program that the towlower() routine is
4141           available.
4142
4143       "d_towupper"
4144           From d_towupper.U:
4145
4146           This variable conditionally defines the "HAS_TOWUPPER" symbol,
4147           which indicates to the C program that the towupper() routine is
4148           available.
4149
4150       "d_trunc"
4151           From d_trunc.U:
4152
4153           This variable conditionally defines the "HAS_TRUNC" symbol, which
4154           indicates to the C program that the trunc() routine is available to
4155           round doubles towards zero.
4156
4157       "d_truncate"
4158           From d_truncate.U:
4159
4160           This variable conditionally defines "HAS_TRUNCATE" if truncate() is
4161           available to truncate files.
4162
4163       "d_truncl"
4164           From d_truncl.U:
4165
4166           This variable conditionally defines the "HAS_TRUNCL" symbol, which
4167           indicates to the C program that the truncl() routine is available
4168           to round long doubles towards zero. If copysignl is also present,
4169           we can emulate modfl.
4170
4171       "d_ttyname_r"
4172           From d_ttyname_r.U:
4173
4174           This variable conditionally defines the "HAS_TTYNAME_R" symbol,
4175           which indicates to the C program that the ttyname_r() routine is
4176           available.
4177
4178       "d_tzname"
4179           From d_tzname.U:
4180
4181           This variable conditionally defines "HAS_TZNAME" if tzname[] is
4182           available to access timezone names.
4183
4184       "d_u32align"
4185           From d_u32align.U:
4186
4187           This variable tells whether you must access character data through
4188           U32-aligned pointers.
4189
4190       "d_ualarm"
4191           From d_ualarm.U:
4192
4193           This variable conditionally defines the "HAS_UALARM" symbol, which
4194           indicates to the C program that the ualarm() routine is available.
4195
4196       "d_umask"
4197           From d_umask.U:
4198
4199           This variable conditionally defines the "HAS_UMASK" symbol, which
4200           indicates to the C program that the umask() routine is available.
4201           to set and get the value of the file creation mask.
4202
4203       "d_uname"
4204           From d_gethname.U:
4205
4206           This variable conditionally defines the "HAS_UNAME" symbol, which
4207           indicates to the C program that the uname() routine may be used to
4208           derive the host name.
4209
4210       "d_union_semun"
4211           From d_union_semun.U:
4212
4213           This variable conditionally defines "HAS_UNION_SEMUN" if the union
4214           semun is defined by including <sys/sem.h>.
4215
4216       "d_unlinkat"
4217           From d_fsat.U:
4218
4219           This variable conditionally defines the "HAS_UNLINKAT" symbol,
4220           which indicates the "POSIX" unlinkat() function isavailable.
4221
4222       "d_unordered"
4223           From d_unordered.U:
4224
4225           This variable conditionally defines the "HAS_UNORDERED" symbol,
4226           which indicates to the C program that the unordered() routine is
4227           available.
4228
4229       "d_unsetenv"
4230           From d_unsetenv.U:
4231
4232           This variable conditionally defines the "HAS_UNSETENV" symbol,
4233           which indicates to the C program that the unsetenv () routine is
4234           available.
4235
4236       "d_uselocale"
4237           From d_newlocale.U:
4238
4239           This variable conditionally defines the "HAS_USELOCALE" symbol,
4240           which indicates to the C program that the uselocale() routine is
4241           available to set the current locale for the calling thread.
4242
4243       "d_usleep"
4244           From d_usleep.U:
4245
4246           This variable conditionally defines "HAS_USLEEP" if usleep() is
4247           available to do high granularity sleeps.
4248
4249       "d_usleepproto"
4250           From d_usleepproto.U:
4251
4252           This variable conditionally defines the "HAS_USLEEP_PROTO" symbol,
4253           which indicates to the C program that the system provides a
4254           prototype for the usleep() function.  Otherwise, it is up to the
4255           program to supply one.
4256
4257       "d_ustat"
4258           From d_ustat.U:
4259
4260           This variable conditionally defines "HAS_USTAT" if ustat() is
4261           available to query file system statistics by dev_t.
4262
4263       "d_vendorarch"
4264           From vendorarch.U:
4265
4266           This variable conditionally defined "PERL_VENDORARCH".
4267
4268       "d_vendorbin"
4269           From vendorbin.U:
4270
4271           This variable conditionally defines "PERL_VENDORBIN".
4272
4273       "d_vendorlib"
4274           From vendorlib.U:
4275
4276           This variable conditionally defines "PERL_VENDORLIB".
4277
4278       "d_vendorscript"
4279           From vendorscript.U:
4280
4281           This variable conditionally defines "PERL_VENDORSCRIPT".
4282
4283       "d_vfork"
4284           From d_vfork.U:
4285
4286           This variable conditionally defines the "HAS_VFORK" symbol, which
4287           indicates the vfork() routine is available.
4288
4289       "d_void_closedir"
4290           From d_closedir.U:
4291
4292           This variable conditionally defines "VOID_CLOSEDIR" if closedir()
4293           does not return a value.
4294
4295       "d_voidsig"
4296           From d_voidsig.U:
4297
4298           This variable conditionally defines "VOIDSIG" if this system
4299           declares "void (*signal(...))()" in signal.h.  The old way was to
4300           declare it as "int (*signal(...))()".
4301
4302       "d_voidtty"
4303           From i_sysioctl.U:
4304
4305           This variable conditionally defines "USE_IOCNOTTY" to indicate that
4306           the ioctl() call with "TIOCNOTTY" should be used to void tty
4307           association.  Otherwise (on "USG" probably), it is enough to close
4308           the standard file descriptors and do a setpgrp().
4309
4310       "d_vsnprintf"
4311           From d_snprintf.U:
4312
4313           This variable conditionally defines the "HAS_VSNPRINTF" symbol,
4314           which indicates to the C program that the vsnprintf () library
4315           function is available.
4316
4317       "d_wait4"
4318           From d_wait4.U:
4319
4320           This variable conditionally defines the HAS_WAIT4 symbol, which
4321           indicates the wait4() routine is available.
4322
4323       "d_waitpid"
4324           From d_waitpid.U:
4325
4326           This variable conditionally defines "HAS_WAITPID" if waitpid() is
4327           available to wait for child process.
4328
4329       "d_wcscmp"
4330           From d_wcscmp.U:
4331
4332           This variable conditionally defines the "HAS_WCSCMP" symbol if the
4333           wcscmp() routine is available and can be used to compare wide
4334           character strings.
4335
4336       "d_wcstombs"
4337           From d_wcstombs.U:
4338
4339           This variable conditionally defines the "HAS_WCSTOMBS" symbol,
4340           which indicates to the C program that the wcstombs() routine is
4341           available to convert wide character strings to multibyte strings.
4342
4343       "d_wcsxfrm"
4344           From d_wcsxfrm.U:
4345
4346           This variable conditionally defines the "HAS_WCSXFRM" symbol if the
4347           wcsxfrm() routine is available and can be used to compare wide
4348           character strings.
4349
4350       "d_wctomb"
4351           From d_wctomb.U:
4352
4353           This variable conditionally defines the "HAS_WCTOMB" symbol, which
4354           indicates to the C program that the wctomb() routine is available
4355           to convert a wide character to a multibyte.
4356
4357       "d_writev"
4358           From d_writev.U:
4359
4360           This variable conditionally defines the "HAS_WRITEV" symbol, which
4361           indicates to the C program that the writev() routine is available.
4362
4363       "d_xenix"
4364           From Guess.U:
4365
4366           This variable conditionally defines the symbol "XENIX", which
4367           alerts the C program that it runs under Xenix.
4368
4369       "date"
4370           From Loc.U:
4371
4372           This variable is used internally by Configure to determine the full
4373           pathname (if any) of the date program.  After Configure runs, the
4374           value is reset to a plain "date" and is not useful.
4375
4376       "db_hashtype"
4377           From i_db.U:
4378
4379           This variable contains the type of the hash structure element in
4380           the <db.h> header file.  In older versions of "DB", it was int,
4381           while in newer ones it is u_int32_t.
4382
4383       "db_prefixtype"
4384           From i_db.U:
4385
4386           This variable contains the type of the prefix structure element in
4387           the <db.h> header file.  In older versions of "DB", it was int,
4388           while in newer ones it is size_t.
4389
4390       "db_version_major"
4391           From i_db.U:
4392
4393           This variable contains the major version number of Berkeley "DB"
4394           found in the <db.h> header file.
4395
4396       "db_version_minor"
4397           From i_db.U:
4398
4399           This variable contains the minor version number of Berkeley "DB"
4400           found in the <db.h> header file.  For "DB" version 1 this is always
4401           0.
4402
4403       "db_version_patch"
4404           From i_db.U:
4405
4406           This variable contains the patch version number of Berkeley "DB"
4407           found in the <db.h> header file.  For "DB" version 1 this is always
4408           0.
4409
4410       "default_inc_excludes_dot"
4411           From defaultincdot.U:
4412
4413           When defined, remove the legacy . from @"INC"
4414
4415       "direntrytype"
4416           From i_dirent.U:
4417
4418           This symbol is set to "struct direct" or "struct dirent" depending
4419           on whether dirent is available or not. You should use this pseudo
4420           type to portably declare your directory entries.
4421
4422       "dlext"
4423           From dlext.U:
4424
4425           This variable contains the extension that is to be used for the
4426           dynamically loaded modules that perl generates.
4427
4428       "dlsrc"
4429           From dlsrc.U:
4430
4431           This variable contains the name of the dynamic loading file that
4432           will be used with the package.
4433
4434       "doubleinfbytes"
4435           From infnan.U:
4436
4437           This variable contains comma-separated list of hexadecimal bytes
4438           for the double precision infinity.
4439
4440       "doublekind"
4441           From longdblfio.U:
4442
4443           This variable, if defined, encodes the type of a double: 1 = "IEEE"
4444           754 32-bit little endian, 2 = "IEEE" 754 32-bit big endian, 3 =
4445           "IEEE" 754 64-bit little endian, 4 = "IEEE" 754 64-bit big endian,
4446           5 = "IEEE" 754 128-bit little endian, 6 = "IEEE" 754 128-bit big
4447           endian, 7 = "IEEE" 754 64-bit mixed endian le-be, 8 = "IEEE" 754
4448           64-bit mixed endian be-le, 9 = "VAX" 32bit little endian F float
4449           format 10 = "VAX" 64bit little endian D float format 11 = "VAX"
4450           64bit little endian G float format 12 = "IBM" 32bit format 13 =
4451           "IBM" 64bit format 14 = Cray 64bit format -1 = unknown format.
4452
4453       "doublemantbits"
4454           From mantbits.U:
4455
4456           This symbol, if defined, tells how many mantissa bits there are in
4457           double precision floating point format.  Note that this is usually
4458           "DBL_MANT_DIG" minus one, since with the standard "IEEE" 754
4459           formats "DBL_MANT_DIG" includes the implicit bit which doesn't
4460           really exist.
4461
4462       "doublenanbytes"
4463           From infnan.U:
4464
4465           This variable contains comma-separated list of hexadecimal bytes
4466           for the double precision not-a-number.
4467
4468       "doublesize"
4469           From doublesize.U:
4470
4471           This variable contains the value of the "DOUBLESIZE" symbol, which
4472           indicates to the C program how many bytes there are in a double.
4473
4474       "drand01"
4475           From randfunc.U:
4476
4477           Indicates the macro to be used to generate normalized random
4478           numbers.  Uses randfunc, often divided by (double) (((unsigned
4479           long) 1 << randbits)) in order to normalize the result.  In C
4480           programs, the macro "Drand01" is mapped to drand01.
4481
4482       "drand48_r_proto"
4483           From d_drand48_r.U:
4484
4485           This variable encodes the prototype of drand48_r.  It is zero if
4486           d_drand48_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
4487           of reentr.h if d_drand48_r is defined.
4488
4489       "dtrace"
4490           From usedtrace.U:
4491
4492           This variable holds the location of the dtrace executable.
4493
4494       "dtraceobject"
4495           From dtraceobject.U:
4496
4497           Whether we need to build an object file with the dtrace tool.
4498
4499       "dtracexnolibs"
4500           From dtraceobject.U:
4501
4502           Whether dtrace accepts -xnolibs.  If available we call dtrace -h
4503           and dtrace -G with -xnolibs to allow dtrace to run in a jail on
4504           FreeBSD.
4505
4506       "dynamic_ext"
4507           From Extensions.U:
4508
4509           This variable holds a list of "XS" extension files we want to link
4510           dynamically into the package.  It is used by Makefile.
4511
4512   e
4513       "eagain"
4514           From nblock_io.U:
4515
4516           This variable bears the symbolic errno code set by read() when no
4517           data is present on the file and non-blocking I/O was enabled
4518           (otherwise, read() blocks naturally).
4519
4520       "ebcdic"
4521           From ebcdic.U:
4522
4523           This variable conditionally defines "EBCDIC" if this system uses
4524           "EBCDIC" encoding.
4525
4526       "echo"
4527           From Loc.U:
4528
4529           This variable is used internally by Configure to determine the full
4530           pathname (if any) of the echo program.  After Configure runs, the
4531           value is reset to a plain "echo" and is not useful.
4532
4533       "egrep"
4534           From Loc.U:
4535
4536           This variable is used internally by Configure to determine the full
4537           pathname (if any) of the egrep program.  After Configure runs, the
4538           value is reset to a plain "egrep" and is not useful.
4539
4540       "emacs"
4541           From Loc.U:
4542
4543           This variable is defined but not used by Configure.  The value is
4544           the empty string and is not useful.
4545
4546       "endgrent_r_proto"
4547           From d_endgrent_r.U:
4548
4549           This variable encodes the prototype of endgrent_r.  It is zero if
4550           d_endgrent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4551           macros of reentr.h if d_endgrent_r is defined.
4552
4553       "endhostent_r_proto"
4554           From d_endhostent_r.U:
4555
4556           This variable encodes the prototype of endhostent_r.  It is zero if
4557           d_endhostent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4558           macros of reentr.h if d_endhostent_r is defined.
4559
4560       "endnetent_r_proto"
4561           From d_endnetent_r.U:
4562
4563           This variable encodes the prototype of endnetent_r.  It is zero if
4564           d_endnetent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4565           macros of reentr.h if d_endnetent_r is defined.
4566
4567       "endprotoent_r_proto"
4568           From d_endprotoent_r.U:
4569
4570           This variable encodes the prototype of endprotoent_r.  It is zero
4571           if d_endprotoent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4572           macros of reentr.h if d_endprotoent_r is defined.
4573
4574       "endpwent_r_proto"
4575           From d_endpwent_r.U:
4576
4577           This variable encodes the prototype of endpwent_r.  It is zero if
4578           d_endpwent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4579           macros of reentr.h if d_endpwent_r is defined.
4580
4581       "endservent_r_proto"
4582           From d_endservent_r.U:
4583
4584           This variable encodes the prototype of endservent_r.  It is zero if
4585           d_endservent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4586           macros of reentr.h if d_endservent_r is defined.
4587
4588       "eunicefix"
4589           From Init.U:
4590
4591           When running under Eunice this variable contains a command which
4592           will convert a shell script to the proper form of text file for it
4593           to be executable by the shell.  On other systems it is a no-op.
4594
4595       "exe_ext"
4596           From Unix.U:
4597
4598           This is an old synonym for _exe.
4599
4600       "expr"
4601           From Loc.U:
4602
4603           This variable is used internally by Configure to determine the full
4604           pathname (if any) of the expr program.  After Configure runs, the
4605           value is reset to a plain "expr" and is not useful.
4606
4607       "extensions"
4608           From Extensions.U:
4609
4610           This variable holds a list of all extension files (both "XS" and
4611           non-xs) installed with the package.  It is propagated to Config.pm
4612           and is typically used to test whether a particular extension is
4613           available.
4614
4615       "extern_C"
4616           From Csym.U:
4617
4618           "ANSI" C requires "extern" where C++ requires 'extern "C"'. This
4619           variable can be used in Configure to do the right thing.
4620
4621       "extras"
4622           From Extras.U:
4623
4624           This variable holds a list of extra modules to install.
4625
4626   f
4627       "fflushall"
4628           From fflushall.U:
4629
4630           This symbol, if defined, tells that to flush all pending stdio
4631           output one must loop through all the stdio file handles stored in
4632           an array and fflush them.  Note that if fflushNULL is defined,
4633           fflushall will not even be probed for and will be left undefined.
4634
4635       "fflushNULL"
4636           From fflushall.U:
4637
4638           This symbol, if defined, tells that fflush("NULL") correctly
4639           flushes all pending stdio output without side effects. In
4640           particular, on some platforms calling fflush("NULL") *still*
4641           corrupts "STDIN" if it is a pipe.
4642
4643       "find"
4644           From Loc.U:
4645
4646           This variable is defined but not used by Configure.  The value is
4647           the empty string and is not useful.
4648
4649       "firstmakefile"
4650           From Unix.U:
4651
4652           This variable defines the first file searched by make.  On unix, it
4653           is makefile (then Makefile).  On case-insensitive systems, it might
4654           be something else.  This is only used to deal with convoluted make
4655           depend tricks.
4656
4657       "flex"
4658           From Loc.U:
4659
4660           This variable is defined but not used by Configure.  The value is
4661           the empty string and is not useful.
4662
4663       "fpossize"
4664           From fpossize.U:
4665
4666           This variable contains the size of a fpostype in bytes.
4667
4668       "fpostype"
4669           From fpostype.U:
4670
4671           This variable defines Fpos_t to be something like fpos_t, long,
4672           uint, or whatever type is used to declare file positions in libc.
4673
4674       "freetype"
4675           From mallocsrc.U:
4676
4677           This variable contains the return type of free().  It is usually
4678           void, but occasionally int.
4679
4680       "from"
4681           From Cross.U:
4682
4683           This variable contains the command used by Configure to copy files
4684           from the target host.  Useful and available only during Perl build.
4685           The string ":" if not cross-compiling.
4686
4687       "full_ar"
4688           From Loc_ar.U:
4689
4690           This variable contains the full pathname to "ar", whether or not
4691           the user has specified "portability".  This is only used in the
4692           Makefile.SH.
4693
4694       "full_csh"
4695           From d_csh.U:
4696
4697           This variable contains the full pathname to "csh", whether or not
4698           the user has specified "portability".  This is only used in the
4699           compiled C program, and we assume that all systems which can share
4700           this executable will have the same full pathname to csh.
4701
4702       "full_sed"
4703           From Loc_sed.U:
4704
4705           This variable contains the full pathname to "sed", whether or not
4706           the user has specified "portability".  This is only used in the
4707           compiled C program, and we assume that all systems which can share
4708           this executable will have the same full pathname to sed.
4709
4710   g
4711       "gccansipedantic"
4712           From gccvers.U:
4713
4714           If "GNU" cc (gcc) is used, this variable will enable (if set) the
4715           -ansi and -pedantic ccflags for building core files (through cflags
4716           script). (See Porting/pumpkin.pod for full description).
4717
4718       "gccosandvers"
4719           From gccvers.U:
4720
4721           If "GNU" cc (gcc) is used, this variable holds the operating system
4722           and version used to compile gcc.  It is set to '' if not gcc, or if
4723           nothing useful can be parsed as the os version.
4724
4725       "gccversion"
4726           From gccvers.U:
4727
4728           If "GNU" cc (gcc) is used, this variable holds 1 or 2 to indicate
4729           whether the compiler is version 1 or 2.  This is used in setting
4730           some of the default cflags.  It is set to '' if not gcc.
4731
4732       "getgrent_r_proto"
4733           From d_getgrent_r.U:
4734
4735           This variable encodes the prototype of getgrent_r.  It is zero if
4736           d_getgrent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4737           macros of reentr.h if d_getgrent_r is defined.
4738
4739       "getgrgid_r_proto"
4740           From d_getgrgid_r.U:
4741
4742           This variable encodes the prototype of getgrgid_r.  It is zero if
4743           d_getgrgid_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4744           macros of reentr.h if d_getgrgid_r is defined.
4745
4746       "getgrnam_r_proto"
4747           From d_getgrnam_r.U:
4748
4749           This variable encodes the prototype of getgrnam_r.  It is zero if
4750           d_getgrnam_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4751           macros of reentr.h if d_getgrnam_r is defined.
4752
4753       "gethostbyaddr_r_proto"
4754           From d_gethostbyaddr_r.U:
4755
4756           This variable encodes the prototype of gethostbyaddr_r.  It is zero
4757           if d_gethostbyaddr_r is undef, and one of the
4758           "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_gethostbyaddr_r is
4759           defined.
4760
4761       "gethostbyname_r_proto"
4762           From d_gethostbyname_r.U:
4763
4764           This variable encodes the prototype of gethostbyname_r.  It is zero
4765           if d_gethostbyname_r is undef, and one of the
4766           "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_gethostbyname_r is
4767           defined.
4768
4769       "gethostent_r_proto"
4770           From d_gethostent_r.U:
4771
4772           This variable encodes the prototype of gethostent_r.  It is zero if
4773           d_gethostent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4774           macros of reentr.h if d_gethostent_r is defined.
4775
4776       "getlogin_r_proto"
4777           From d_getlogin_r.U:
4778
4779           This variable encodes the prototype of getlogin_r.  It is zero if
4780           d_getlogin_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4781           macros of reentr.h if d_getlogin_r is defined.
4782
4783       "getnetbyaddr_r_proto"
4784           From d_getnetbyaddr_r.U:
4785
4786           This variable encodes the prototype of getnetbyaddr_r.  It is zero
4787           if d_getnetbyaddr_r is undef, and one of the
4788           "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getnetbyaddr_r is
4789           defined.
4790
4791       "getnetbyname_r_proto"
4792           From d_getnetbyname_r.U:
4793
4794           This variable encodes the prototype of getnetbyname_r.  It is zero
4795           if d_getnetbyname_r is undef, and one of the
4796           "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getnetbyname_r is
4797           defined.
4798
4799       "getnetent_r_proto"
4800           From d_getnetent_r.U:
4801
4802           This variable encodes the prototype of getnetent_r.  It is zero if
4803           d_getnetent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4804           macros of reentr.h if d_getnetent_r is defined.
4805
4806       "getprotobyname_r_proto"
4807           From d_getprotobyname_r.U:
4808
4809           This variable encodes the prototype of getprotobyname_r.  It is
4810           zero if d_getprotobyname_r is undef, and one of the
4811           "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getprotobyname_r is
4812           defined.
4813
4814       "getprotobynumber_r_proto"
4815           From d_getprotobynumber_r.U:
4816
4817           This variable encodes the prototype of getprotobynumber_r.  It is
4818           zero if d_getprotobynumber_r is undef, and one of the
4819           "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getprotobynumber_r
4820           is defined.
4821
4822       "getprotoent_r_proto"
4823           From d_getprotoent_r.U:
4824
4825           This variable encodes the prototype of getprotoent_r.  It is zero
4826           if d_getprotoent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4827           macros of reentr.h if d_getprotoent_r is defined.
4828
4829       "getpwent_r_proto"
4830           From d_getpwent_r.U:
4831
4832           This variable encodes the prototype of getpwent_r.  It is zero if
4833           d_getpwent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4834           macros of reentr.h if d_getpwent_r is defined.
4835
4836       "getpwnam_r_proto"
4837           From d_getpwnam_r.U:
4838
4839           This variable encodes the prototype of getpwnam_r.  It is zero if
4840           d_getpwnam_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4841           macros of reentr.h if d_getpwnam_r is defined.
4842
4843       "getpwuid_r_proto"
4844           From d_getpwuid_r.U:
4845
4846           This variable encodes the prototype of getpwuid_r.  It is zero if
4847           d_getpwuid_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4848           macros of reentr.h if d_getpwuid_r is defined.
4849
4850       "getservbyname_r_proto"
4851           From d_getservbyname_r.U:
4852
4853           This variable encodes the prototype of getservbyname_r.  It is zero
4854           if d_getservbyname_r is undef, and one of the
4855           "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getservbyname_r is
4856           defined.
4857
4858       "getservbyport_r_proto"
4859           From d_getservbyport_r.U:
4860
4861           This variable encodes the prototype of getservbyport_r.  It is zero
4862           if d_getservbyport_r is undef, and one of the
4863           "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getservbyport_r is
4864           defined.
4865
4866       "getservent_r_proto"
4867           From d_getservent_r.U:
4868
4869           This variable encodes the prototype of getservent_r.  It is zero if
4870           d_getservent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4871           macros of reentr.h if d_getservent_r is defined.
4872
4873       "getspnam_r_proto"
4874           From d_getspnam_r.U:
4875
4876           This variable encodes the prototype of getspnam_r.  It is zero if
4877           d_getspnam_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4878           macros of reentr.h if d_getspnam_r is defined.
4879
4880       "gidformat"
4881           From gidf.U:
4882
4883           This variable contains the format string used for printing a Gid_t.
4884
4885       "gidsign"
4886           From gidsign.U:
4887
4888           This variable contains the signedness of a gidtype.  1 for
4889           unsigned, -1 for signed.
4890
4891       "gidsize"
4892           From gidsize.U:
4893
4894           This variable contains the size of a gidtype in bytes.
4895
4896       "gidtype"
4897           From gidtype.U:
4898
4899           This variable defines Gid_t to be something like gid_t, int,
4900           ushort, or whatever type is used to declare the return type of
4901           getgid().  Typically, it is the type of group ids in the kernel.
4902
4903       "glibpth"
4904           From libpth.U:
4905
4906           This variable holds the general path (space-separated) used to find
4907           libraries.  It may contain directories that do not exist on this
4908           platform, libpth is the cleaned-up version.
4909
4910       "gmake"
4911           From Loc.U:
4912
4913           This variable is used internally by Configure to determine the full
4914           pathname (if any) of the gmake program.  After Configure runs, the
4915           value is reset to a plain "gmake" and is not useful.
4916
4917       "gmtime_r_proto"
4918           From d_gmtime_r.U:
4919
4920           This variable encodes the prototype of gmtime_r.  It is zero if
4921           d_gmtime_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
4922           of reentr.h if d_gmtime_r is defined.
4923
4924       "gnulibc_version"
4925           From d_gnulibc.U:
4926
4927           This variable contains the version number of the "GNU" C library.
4928           It is usually something like 2.2.5.  It is a plain '' if this is
4929           not the "GNU" C library, or if the version is unknown.
4930
4931       "grep"
4932           From Loc.U:
4933
4934           This variable is used internally by Configure to determine the full
4935           pathname (if any) of the grep program.  After Configure runs, the
4936           value is reset to a plain "grep" and is not useful.
4937
4938       "groupcat"
4939           From nis.U:
4940
4941           This variable contains a command that produces the text of the
4942           /etc/group file.  This is normally "cat /etc/group", but can be
4943           "ypcat group" when "NIS" is used.  On some systems, such as os390,
4944           there may be no equivalent command, in which case this variable is
4945           unset.
4946
4947       "groupstype"
4948           From groupstype.U:
4949
4950           This variable defines Groups_t to be something like gid_t, int,
4951           ushort, or whatever type is used for the second argument to
4952           getgroups() and setgroups().  Usually, this is the same as gidtype
4953           (gid_t), but sometimes it isn't.
4954
4955       "gzip"
4956           From Loc.U:
4957
4958           This variable is used internally by Configure to determine the full
4959           pathname (if any) of the gzip program.  After Configure runs, the
4960           value is reset to a plain "gzip" and is not useful.
4961
4962   h
4963       "h_fcntl"
4964           From h_fcntl.U:
4965
4966           This is variable gets set in various places to tell i_fcntl that
4967           <fcntl.h> should be included.
4968
4969       "h_sysfile"
4970           From h_sysfile.U:
4971
4972           This is variable gets set in various places to tell i_sys_file that
4973           <sys/file.h> should be included.
4974
4975       "hint"
4976           From Oldconfig.U:
4977
4978           Gives the type of hints used for previous answers. May be one of
4979           "default", "recommended" or "previous".
4980
4981       "hostcat"
4982           From nis.U:
4983
4984           This variable contains a command that produces the text of the
4985           /etc/hosts file.  This is normally "cat /etc/hosts", but can be
4986           "ypcat hosts" when "NIS" is used.  On some systems, such as os390,
4987           there may be no equivalent command, in which case this variable is
4988           unset.
4989
4990       "hostgenerate"
4991           From Cross.U:
4992
4993           This variable contains the path to a generate_uudmap binary that
4994           can be run on the host "OS" when cross-compiling.  Useful and
4995           available only during Perl build.  Empty string '' if not cross-
4996           compiling.
4997
4998       "hostosname"
4999           From Cross.U:
5000
5001           This variable contains the original value of $^O for hostperl when
5002           cross-compiling.  This is useful to pick the proper tools when
5003           running build code in the host.  Empty string '' if not cross-
5004           compiling.
5005
5006       "hostperl"
5007           From Cross.U:
5008
5009           This variable contains the path to a miniperl binary that can be
5010           run on the host "OS" when cross-compiling.  Useful and available
5011           only during Perl build.  Empty string '' if not cross-compiling.
5012
5013       "html1dir"
5014           From html1dir.U:
5015
5016           This variable contains the name of the directory in which html
5017           source pages are to be put.  This directory is for pages that
5018           describe whole programs, not libraries or modules.  It is intended
5019           to correspond roughly to section 1 of the Unix manuals.
5020
5021       "html1direxp"
5022           From html1dir.U:
5023
5024           This variable is the same as the html1dir variable, but is filename
5025           expanded at configuration time, for convenient use in makefiles.
5026
5027       "html3dir"
5028           From html3dir.U:
5029
5030           This variable contains the name of the directory in which html
5031           source pages are to be put.  This directory is for pages that
5032           describe libraries or modules.  It is intended to correspond
5033           roughly to section 3 of the Unix manuals.
5034
5035       "html3direxp"
5036           From html3dir.U:
5037
5038           This variable is the same as the html3dir variable, but is filename
5039           expanded at configuration time, for convenient use in makefiles.
5040
5041   i
5042       "i16size"
5043           From perlxv.U:
5044
5045           This variable is the size of an I16 in bytes.
5046
5047       "i16type"
5048           From perlxv.U:
5049
5050           This variable contains the C type used for Perl's I16.
5051
5052       "i32size"
5053           From perlxv.U:
5054
5055           This variable is the size of an I32 in bytes.
5056
5057       "i32type"
5058           From perlxv.U:
5059
5060           This variable contains the C type used for Perl's I32.
5061
5062       "i64size"
5063           From perlxv.U:
5064
5065           This variable is the size of an I64 in bytes.
5066
5067       "i64type"
5068           From perlxv.U:
5069
5070           This variable contains the C type used for Perl's I64.
5071
5072       "i8size"
5073           From perlxv.U:
5074
5075           This variable is the size of an I8 in bytes.
5076
5077       "i8type"
5078           From perlxv.U:
5079
5080           This variable contains the C type used for Perl's I8.
5081
5082       "i_arpainet"
5083           From i_arpainet.U:
5084
5085           This variable conditionally defines the "I_ARPA_INET" symbol, and
5086           indicates whether a C program should include <arpa/inet.h>.
5087
5088       "i_bfd"
5089           From i_bfd.U:
5090
5091           This variable conditionally defines the "I_BFD" symbol, and
5092           indicates whether a C program can include <bfd.h>.
5093
5094       "i_bsdioctl"
5095           From i_sysioctl.U:
5096
5097           This variable conditionally defines the "I_SYS_BSDIOCTL" symbol,
5098           which indicates to the C program that <sys/bsdioctl.h> exists and
5099           should be included.
5100
5101       "i_crypt"
5102           From i_crypt.U:
5103
5104           This variable conditionally defines the "I_CRYPT" symbol, and
5105           indicates whether a C program should include <crypt.h>.
5106
5107       "i_db"
5108           From i_db.U:
5109
5110           This variable conditionally defines the "I_DB" symbol, and
5111           indicates whether a C program may include Berkeley's "DB" include
5112           file <db.h>.
5113
5114       "i_dbm"
5115           From i_dbm.U:
5116
5117           This variable conditionally defines the "I_DBM" symbol, which
5118           indicates to the C program that <dbm.h> exists and should be
5119           included.
5120
5121       "i_dirent"
5122           From i_dirent.U:
5123
5124           This variable conditionally defines "I_DIRENT", which indicates to
5125           the C program that it should include <dirent.h>.
5126
5127       "i_dlfcn"
5128           From i_dlfcn.U:
5129
5130           This variable conditionally defines the "I_DLFCN" symbol, which
5131           indicates to the C program that <dlfcn.h> exists and should be
5132           included.
5133
5134       "i_execinfo"
5135           From i_execinfo.U:
5136
5137           This variable conditionally defines the "I_EXECINFO" symbol, and
5138           indicates whether a C program may include <execinfo.h>, for
5139           backtrace() support.
5140
5141       "i_fcntl"
5142           From i_fcntl.U:
5143
5144           This variable controls the value of "I_FCNTL" (which tells the C
5145           program to include <fcntl.h>).
5146
5147       "i_fenv"
5148           From i_fenv.U:
5149
5150           This variable conditionally defines the "I_FENV" symbol, which
5151           indicates to the C program that <fenv.h> exists and should be
5152           included.
5153
5154       "i_fp"
5155           From i_fp.U:
5156
5157           This variable conditionally defines the "I_FP" symbol, and
5158           indicates whether a C program should include <fp.h>.
5159
5160       "i_fp_class"
5161           From i_fp_class.U:
5162
5163           This variable conditionally defines the "I_FP_CLASS" symbol, and
5164           indicates whether a C program should include <fp_class.h>.
5165
5166       "i_gdbm"
5167           From i_gdbm.U:
5168
5169           This variable conditionally defines the "I_GDBM" symbol, which
5170           indicates to the C program that <gdbm.h> exists and should be
5171           included.
5172
5173       "i_gdbm_ndbm"
5174           From i_ndbm.U:
5175
5176           This variable conditionally defines the "I_GDBM_NDBM" symbol, which
5177           indicates to the C program that <gdbm-ndbm.h> exists and should be
5178           included.  This is the location of the ndbm.h compatibility file in
5179           Debian 4.0.
5180
5181       "i_gdbmndbm"
5182           From i_ndbm.U:
5183
5184           This variable conditionally defines the "I_GDBMNDBM" symbol, which
5185           indicates to the C program that <gdbm/ndbm.h> exists and should be
5186           included.  This was the location of the ndbm.h compatibility file
5187           in RedHat 7.1.
5188
5189       "i_grp"
5190           From i_grp.U:
5191
5192           This variable conditionally defines the "I_GRP" symbol, and
5193           indicates whether a C program should include <grp.h>.
5194
5195       "i_ieeefp"
5196           From i_ieeefp.U:
5197
5198           This variable conditionally defines the "I_IEEEFP" symbol, and
5199           indicates whether a C program should include <ieeefp.h>.
5200
5201       "i_inttypes"
5202           From i_inttypes.U:
5203
5204           This variable conditionally defines the "I_INTTYPES" symbol, and
5205           indicates whether a C program should include <inttypes.h>.
5206
5207       "i_langinfo"
5208           From i_langinfo.U:
5209
5210           This variable conditionally defines the "I_LANGINFO" symbol, and
5211           indicates whether a C program should include <langinfo.h>.
5212
5213       "i_libutil"
5214           From i_libutil.U:
5215
5216           This variable conditionally defines the "I_LIBUTIL" symbol, and
5217           indicates whether a C program should include <libutil.h>.
5218
5219       "i_locale"
5220           From i_locale.U:
5221
5222           This variable conditionally defines the "I_LOCALE" symbol, and
5223           indicates whether a C program should include <locale.h>.
5224
5225       "i_machcthr"
5226           From i_machcthr.U:
5227
5228           This variable conditionally defines the "I_MACH_CTHREADS" symbol,
5229           and indicates whether a C program should include <mach/cthreads.h>.
5230
5231       "i_malloc"
5232           From i_malloc.U:
5233
5234           This variable conditionally defines the "I_MALLOC" symbol, and
5235           indicates whether a C program should include <malloc.h>.
5236
5237       "i_mallocmalloc"
5238           From i_mallocmalloc.U:
5239
5240           This variable conditionally defines the "I_MALLOCMALLOC" symbol,
5241           and indicates whether a C program should include <malloc/malloc.h>.
5242
5243       "i_mntent"
5244           From i_mntent.U:
5245
5246           This variable conditionally defines the "I_MNTENT" symbol, and
5247           indicates whether a C program should include <mntent.h>.
5248
5249       "i_ndbm"
5250           From i_ndbm.U:
5251
5252           This variable conditionally defines the "I_NDBM" symbol, which
5253           indicates to the C program that <ndbm.h> exists and should be
5254           included.
5255
5256       "i_netdb"
5257           From i_netdb.U:
5258
5259           This variable conditionally defines the "I_NETDB" symbol, and
5260           indicates whether a C program should include <netdb.h>.
5261
5262       "i_neterrno"
5263           From i_neterrno.U:
5264
5265           This variable conditionally defines the "I_NET_ERRNO" symbol, which
5266           indicates to the C program that <net/errno.h> exists and should be
5267           included.
5268
5269       "i_netinettcp"
5270           From i_netinettcp.U:
5271
5272           This variable conditionally defines the "I_NETINET_TCP" symbol, and
5273           indicates whether a C program should include <netinet/tcp.h>.
5274
5275       "i_niin"
5276           From i_niin.U:
5277
5278           This variable conditionally defines "I_NETINET_IN", which indicates
5279           to the C program that it should include <netinet/in.h>. Otherwise,
5280           you may try <sys/in.h>.
5281
5282       "i_poll"
5283           From i_poll.U:
5284
5285           This variable conditionally defines the "I_POLL" symbol, and
5286           indicates whether a C program should include <poll.h>.
5287
5288       "i_prot"
5289           From i_prot.U:
5290
5291           This variable conditionally defines the "I_PROT" symbol, and
5292           indicates whether a C program should include <prot.h>.
5293
5294       "i_pthread"
5295           From i_pthread.U:
5296
5297           This variable conditionally defines the "I_PTHREAD" symbol, and
5298           indicates whether a C program should include <pthread.h>.
5299
5300       "i_pwd"
5301           From i_pwd.U:
5302
5303           This variable conditionally defines "I_PWD", which indicates to the
5304           C program that it should include <pwd.h>.
5305
5306       "i_quadmath"
5307           From i_quadmath.U:
5308
5309           This variable conditionally defines "I_QUADMATH", which indicates
5310           to the C program that it should include <quadmath.h>.
5311
5312       "i_rpcsvcdbm"
5313           From i_dbm.U:
5314
5315           This variable conditionally defines the "I_RPCSVC_DBM" symbol,
5316           which indicates to the C program that <rpcsvc/dbm.h> exists and
5317           should be included.  Some System V systems might need this instead
5318           of <dbm.h>.
5319
5320       "i_sgtty"
5321           From i_termio.U:
5322
5323           This variable conditionally defines the "I_SGTTY" symbol, which
5324           indicates to the C program that it should include <sgtty.h> rather
5325           than <termio.h>.
5326
5327       "i_shadow"
5328           From i_shadow.U:
5329
5330           This variable conditionally defines the "I_SHADOW" symbol, and
5331           indicates whether a C program should include <shadow.h>.
5332
5333       "i_socks"
5334           From i_socks.U:
5335
5336           This variable conditionally defines the "I_SOCKS" symbol, and
5337           indicates whether a C program should include <socks.h>.
5338
5339       "i_stdbool"
5340           From i_stdbool.U:
5341
5342           This variable conditionally defines the "I_STDBOOL" symbol, which
5343           indicates to the C program that <stdbool.h> exists and should be
5344           included.
5345
5346       "i_stdint"
5347           From i_stdint.U:
5348
5349           This variable conditionally defines the "I_STDINT" symbol, which
5350           indicates to the C program that <stdint.h> exists and should be
5351           included.
5352
5353       "i_stdlib"
5354           From i_stdlib.U:
5355
5356           This variable unconditionally defines the "I_STDLIB" symbol.
5357
5358       "i_sunmath"
5359           From i_sunmath.U:
5360
5361           This variable conditionally defines the "I_SUNMATH" symbol, and
5362           indicates whether a C program should include <sunmath.h>.
5363
5364       "i_sysaccess"
5365           From i_sysaccess.U:
5366
5367           This variable conditionally defines the "I_SYS_ACCESS" symbol, and
5368           indicates whether a C program should include <sys/access.h>.
5369
5370       "i_sysdir"
5371           From i_sysdir.U:
5372
5373           This variable conditionally defines the "I_SYS_DIR" symbol, and
5374           indicates whether a C program should include <sys/dir.h>.
5375
5376       "i_sysfile"
5377           From i_sysfile.U:
5378
5379           This variable conditionally defines the "I_SYS_FILE" symbol, and
5380           indicates whether a C program should include <sys/file.h> to get
5381           "R_OK" and friends.
5382
5383       "i_sysfilio"
5384           From i_sysioctl.U:
5385
5386           This variable conditionally defines the "I_SYS_FILIO" symbol, which
5387           indicates to the C program that <sys/filio.h> exists and should be
5388           included in preference to <sys/ioctl.h>.
5389
5390       "i_sysin"
5391           From i_niin.U:
5392
5393           This variable conditionally defines "I_SYS_IN", which indicates to
5394           the C program that it should include <sys/in.h> instead of
5395           <netinet/in.h>.
5396
5397       "i_sysioctl"
5398           From i_sysioctl.U:
5399
5400           This variable conditionally defines the "I_SYS_IOCTL" symbol, which
5401           indicates to the C program that <sys/ioctl.h> exists and should be
5402           included.
5403
5404       "i_syslog"
5405           From i_syslog.U:
5406
5407           This variable conditionally defines the "I_SYSLOG" symbol, and
5408           indicates whether a C program should include <syslog.h>.
5409
5410       "i_sysmman"
5411           From i_sysmman.U:
5412
5413           This variable conditionally defines the "I_SYS_MMAN" symbol, and
5414           indicates whether a C program should include <sys/mman.h>.
5415
5416       "i_sysmode"
5417           From i_sysmode.U:
5418
5419           This variable conditionally defines the "I_SYSMODE" symbol, and
5420           indicates whether a C program should include <sys/mode.h>.
5421
5422       "i_sysmount"
5423           From i_sysmount.U:
5424
5425           This variable conditionally defines the "I_SYSMOUNT" symbol, and
5426           indicates whether a C program should include <sys/mount.h>.
5427
5428       "i_sysndir"
5429           From i_sysndir.U:
5430
5431           This variable conditionally defines the "I_SYS_NDIR" symbol, and
5432           indicates whether a C program should include <sys/ndir.h>.
5433
5434       "i_sysparam"
5435           From i_sysparam.U:
5436
5437           This variable conditionally defines the "I_SYS_PARAM" symbol, and
5438           indicates whether a C program should include <sys/param.h>.
5439
5440       "i_syspoll"
5441           From i_syspoll.U:
5442
5443           This variable conditionally defines the "I_SYS_POLL" symbol, which
5444           indicates to the C program that it should include <sys/poll.h>.
5445
5446       "i_sysresrc"
5447           From i_sysresrc.U:
5448
5449           This variable conditionally defines the "I_SYS_RESOURCE" symbol,
5450           and indicates whether a C program should include <sys/resource.h>.
5451
5452       "i_syssecrt"
5453           From i_syssecrt.U:
5454
5455           This variable conditionally defines the "I_SYS_SECURITY" symbol,
5456           and indicates whether a C program should include <sys/security.h>.
5457
5458       "i_sysselct"
5459           From i_sysselct.U:
5460
5461           This variable conditionally defines "I_SYS_SELECT", which indicates
5462           to the C program that it should include <sys/select.h> in order to
5463           get the definition of struct timeval.
5464
5465       "i_syssockio"
5466           From i_sysioctl.U:
5467
5468           This variable conditionally defines "I_SYS_SOCKIO" to indicate to
5469           the C program that socket ioctl codes may be found in
5470           <sys/sockio.h> instead of <sys/ioctl.h>.
5471
5472       "i_sysstat"
5473           From i_sysstat.U:
5474
5475           This variable conditionally defines the "I_SYS_STAT" symbol, and
5476           indicates whether a C program should include <sys/stat.h>.
5477
5478       "i_sysstatfs"
5479           From i_sysstatfs.U:
5480
5481           This variable conditionally defines the "I_SYSSTATFS" symbol, and
5482           indicates whether a C program should include <sys/statfs.h>.
5483
5484       "i_sysstatvfs"
5485           From i_sysstatvfs.U:
5486
5487           This variable conditionally defines the "I_SYSSTATVFS" symbol, and
5488           indicates whether a C program should include <sys/statvfs.h>.
5489
5490       "i_systime"
5491           From i_time.U:
5492
5493           This variable conditionally defines "I_SYS_TIME", which indicates
5494           to the C program that it should include <sys/time.h>.
5495
5496       "i_systimek"
5497           From i_time.U:
5498
5499           This variable conditionally defines "I_SYS_TIME_KERNEL", which
5500           indicates to the C program that it should include <sys/time.h> with
5501           "KERNEL" defined.
5502
5503       "i_systimes"
5504           From i_systimes.U:
5505
5506           This variable conditionally defines the "I_SYS_TIMES" symbol, and
5507           indicates whether a C program should include <sys/times.h>.
5508
5509       "i_systypes"
5510           From i_systypes.U:
5511
5512           This variable conditionally defines the "I_SYS_TYPES" symbol, and
5513           indicates whether a C program should include <sys/types.h>.
5514
5515       "i_sysuio"
5516           From i_sysuio.U:
5517
5518           This variable conditionally defines the "I_SYSUIO" symbol, and
5519           indicates whether a C program should include <sys/uio.h>.
5520
5521       "i_sysun"
5522           From i_sysun.U:
5523
5524           This variable conditionally defines "I_SYS_UN", which indicates to
5525           the C program that it should include <sys/un.h> to get "UNIX"
5526           domain socket definitions.
5527
5528       "i_sysutsname"
5529           From i_sysutsname.U:
5530
5531           This variable conditionally defines the "I_SYSUTSNAME" symbol, and
5532           indicates whether a C program should include <sys/utsname.h>.
5533
5534       "i_sysvfs"
5535           From i_sysvfs.U:
5536
5537           This variable conditionally defines the "I_SYSVFS" symbol, and
5538           indicates whether a C program should include <sys/vfs.h>.
5539
5540       "i_syswait"
5541           From i_syswait.U:
5542
5543           This variable conditionally defines "I_SYS_WAIT", which indicates
5544           to the C program that it should include <sys/wait.h>.
5545
5546       "i_termio"
5547           From i_termio.U:
5548
5549           This variable conditionally defines the "I_TERMIO" symbol, which
5550           indicates to the C program that it should include <termio.h> rather
5551           than <sgtty.h>.
5552
5553       "i_termios"
5554           From i_termio.U:
5555
5556           This variable conditionally defines the "I_TERMIOS" symbol, which
5557           indicates to the C program that the "POSIX" <termios.h> file is to
5558           be included.
5559
5560       "i_time"
5561           From i_time.U:
5562
5563           This variable unconditionally defines "I_TIME", which indicates to
5564           the C program that it should include <time.h>.
5565
5566       "i_unistd"
5567           From i_unistd.U:
5568
5569           This variable conditionally defines the "I_UNISTD" symbol, and
5570           indicates whether a C program should include <unistd.h>.
5571
5572       "i_ustat"
5573           From i_ustat.U:
5574
5575           This variable conditionally defines the "I_USTAT" symbol, and
5576           indicates whether a C program should include <ustat.h>.
5577
5578       "i_utime"
5579           From i_utime.U:
5580
5581           This variable conditionally defines the "I_UTIME" symbol, and
5582           indicates whether a C program should include <utime.h>.
5583
5584       "i_vfork"
5585           From i_vfork.U:
5586
5587           This variable conditionally defines the "I_VFORK" symbol, and
5588           indicates whether a C program should include vfork.h.
5589
5590       "i_wchar"
5591           From i_wchar.U:
5592
5593           This variable conditionally defines the "I_WCHAR" symbol, that
5594           indicates whether a C program may include <wchar.h>.
5595
5596       "i_wctype"
5597           From i_wctype.U:
5598
5599           This variable conditionally defines the "I_WCTYPE" symbol, that
5600           indicates whether a C program may include <wctype.h>.
5601
5602       "i_xlocale"
5603           From d_newlocale.U:
5604
5605           This symbol, if defined, indicates to the C program that it should
5606           include <xlocale.h> to get uselocale() and its friends
5607
5608       "ignore_versioned_solibs"
5609           From libs.U:
5610
5611           This variable should be non-empty if non-versioned shared libraries
5612           (libfoo.so.x.y) are to be ignored (because they cannot be linked
5613           against).
5614
5615       "inc_version_list"
5616           From inc_version_list.U:
5617
5618           This variable specifies the list of subdirectories in over which
5619           perl.c:incpush() and lib/lib.pm will automatically search when
5620           adding directories to @"INC".  The elements in the list are
5621           separated by spaces.  This is only useful if you have a perl
5622           library directory tree structured like the default one.  See
5623           "INSTALL" for how this works.  The versioned site_perl directory
5624           was introduced in 5.005, so that is the lowest possible value.
5625
5626           This list includes architecture-dependent directories back to
5627           version $api_versionstring (e.g. 5.5.640) and architecture-
5628           independent directories all the way back to 5.005.
5629
5630       "inc_version_list_init"
5631           From inc_version_list.U:
5632
5633           This variable holds the same list as inc_version_list, but each
5634           item is enclosed in double quotes and separated by commas, suitable
5635           for use in the "PERL_INC_VERSION_LIST" initialization.
5636
5637       "incpath"
5638           From usrinc.U:
5639
5640           This variable must precede the normal include path to get the right
5641           one, as in $incpath/usr/include or $incpath/usr/lib.  Value can be
5642           "" or /bsd43 on mips.
5643
5644       "incpth"
5645           From libpth.U:
5646
5647           This variable must precede the normal include path to get the right
5648           one, as in $incpath/usr/include or $incpath/usr/lib.  Value can be
5649           "" or /bsd43 on mips.
5650
5651       "inews"
5652           From Loc.U:
5653
5654           This variable is defined but not used by Configure.  The value is
5655           the empty string and is not useful.
5656
5657       "initialinstalllocation"
5658           From bin.U:
5659
5660           When userelocatableinc is true, this variable holds the location
5661           that make install should copy the perl binary to, with all the run-
5662           time relocatable paths calculated from this at install time.  When
5663           used, it is initialized to the original value of binexp, and then
5664           binexp is set to .../, as the other binaries are found relative to
5665           the perl binary.
5666
5667       "installarchlib"
5668           From archlib.U:
5669
5670           This variable is really the same as archlibexp but may differ on
5671           those systems using "AFS". For extra portability, only this
5672           variable should be used in makefiles.
5673
5674       "installbin"
5675           From bin.U:
5676
5677           This variable is the same as binexp unless "AFS" is running in
5678           which case the user is explicitly prompted for it. This variable
5679           should always be used in your makefiles for maximum portability.
5680
5681       "installhtml1dir"
5682           From html1dir.U:
5683
5684           This variable is really the same as html1direxp, unless you are
5685           using a different installprefix.  For extra portability, you should
5686           only use this variable within your makefiles.
5687
5688       "installhtml3dir"
5689           From html3dir.U:
5690
5691           This variable is really the same as html3direxp, unless you are
5692           using a different installprefix.  For extra portability, you should
5693           only use this variable within your makefiles.
5694
5695       "installman1dir"
5696           From man1dir.U:
5697
5698           This variable is really the same as man1direxp, unless you are
5699           using "AFS" in which case it points to the read/write location
5700           whereas man1direxp only points to the read-only access location.
5701           For extra portability, you should only use this variable within
5702           your makefiles.
5703
5704       "installman3dir"
5705           From man3dir.U:
5706
5707           This variable is really the same as man3direxp, unless you are
5708           using "AFS" in which case it points to the read/write location
5709           whereas man3direxp only points to the read-only access location.
5710           For extra portability, you should only use this variable within
5711           your makefiles.
5712
5713       "installprefix"
5714           From installprefix.U:
5715
5716           This variable holds the name of the directory below which "make
5717           install" will install the package.  For most users, this is the
5718           same as prefix.  However, it is useful for installing the software
5719           into a different (usually temporary) location after which it can be
5720           bundled up and moved somehow to the final location specified by
5721           prefix.
5722
5723       "installprefixexp"
5724           From installprefix.U:
5725
5726           This variable holds the full absolute path of installprefix with
5727           all ~-expansion done.
5728
5729       "installprivlib"
5730           From privlib.U:
5731
5732           This variable is really the same as privlibexp but may differ on
5733           those systems using "AFS". For extra portability, only this
5734           variable should be used in makefiles.
5735
5736       "installscript"
5737           From scriptdir.U:
5738
5739           This variable is usually the same as scriptdirexp, unless you are
5740           on a system running "AFS", in which case they may differ slightly.
5741           You should always use this variable within your makefiles for
5742           portability.
5743
5744       "installsitearch"
5745           From sitearch.U:
5746
5747           This variable is really the same as sitearchexp but may differ on
5748           those systems using "AFS". For extra portability, only this
5749           variable should be used in makefiles.
5750
5751       "installsitebin"
5752           From sitebin.U:
5753
5754           This variable is usually the same as sitebinexp, unless you are on
5755           a system running "AFS", in which case they may differ slightly. You
5756           should always use this variable within your makefiles for
5757           portability.
5758
5759       "installsitehtml1dir"
5760           From sitehtml1dir.U:
5761
5762           This variable is really the same as sitehtml1direxp, unless you are
5763           using "AFS" in which case it points to the read/write location
5764           whereas html1direxp only points to the read-only access location.
5765           For extra portability, you should only use this variable within
5766           your makefiles.
5767
5768       "installsitehtml3dir"
5769           From sitehtml3dir.U:
5770
5771           This variable is really the same as sitehtml3direxp, unless you are
5772           using "AFS" in which case it points to the read/write location
5773           whereas html3direxp only points to the read-only access location.
5774           For extra portability, you should only use this variable within
5775           your makefiles.
5776
5777       "installsitelib"
5778           From sitelib.U:
5779
5780           This variable is really the same as sitelibexp but may differ on
5781           those systems using "AFS". For extra portability, only this
5782           variable should be used in makefiles.
5783
5784       "installsiteman1dir"
5785           From siteman1dir.U:
5786
5787           This variable is really the same as siteman1direxp, unless you are
5788           using "AFS" in which case it points to the read/write location
5789           whereas man1direxp only points to the read-only access location.
5790           For extra portability, you should only use this variable within
5791           your makefiles.
5792
5793       "installsiteman3dir"
5794           From siteman3dir.U:
5795
5796           This variable is really the same as siteman3direxp, unless you are
5797           using "AFS" in which case it points to the read/write location
5798           whereas man3direxp only points to the read-only access location.
5799           For extra portability, you should only use this variable within
5800           your makefiles.
5801
5802       "installsitescript"
5803           From sitescript.U:
5804
5805           This variable is usually the same as sitescriptexp, unless you are
5806           on a system running "AFS", in which case they may differ slightly.
5807           You should always use this variable within your makefiles for
5808           portability.
5809
5810       "installstyle"
5811           From installstyle.U:
5812
5813           This variable describes the "style" of the perl installation.  This
5814           is intended to be useful for tools that need to manipulate entire
5815           perl distributions.  Perl itself doesn't use this to find its
5816           libraries -- the library directories are stored directly in
5817           Config.pm.  Currently, there are only two styles:  "lib" and
5818           lib/perl5.  The default library locations (e.g. privlib, sitelib)
5819           are either $prefix/lib or $prefix/lib/perl5.  The former is useful
5820           if $prefix is a directory dedicated to perl (e.g. /opt/perl), while
5821           the latter is useful if $prefix is shared by many packages, e.g. if
5822           $prefix=/usr/local.
5823
5824           Unfortunately, while this "style" variable is used to set defaults
5825           for all three directory hierarchies (core, vendor, and site), there
5826           is no guarantee that the same style is actually appropriate for all
5827           those directories.  For example, $prefix might be /opt/perl, but
5828           $siteprefix might be /usr/local.  (Perhaps, in retrospect, the
5829           "lib" style should never have been supported, but it did seem like
5830           a nice idea at the time.)
5831
5832           The situation is even less clear for tools such as MakeMaker that
5833           can be used to install additional modules into non-standard places.
5834           For example, if a user intends to install a module into a private
5835           directory (perhaps by setting "PREFIX" on the Makefile.PL command
5836           line), then there is no reason to assume that the Configure-time
5837           $installstyle setting will be relevant for that "PREFIX".
5838
5839           This may later be extended to include other information, so be
5840           careful with pattern-matching on the results.
5841
5842           For compatibility with perl5.005 and earlier, the default setting
5843           is based on whether or not $prefix contains the string "perl".
5844
5845       "installusrbinperl"
5846           From instubperl.U:
5847
5848           This variable tells whether Perl should be installed also as
5849           /usr/bin/perl in addition to $installbin/perl
5850
5851       "installvendorarch"
5852           From vendorarch.U:
5853
5854           This variable is really the same as vendorarchexp but may differ on
5855           those systems using "AFS". For extra portability, only this
5856           variable should be used in makefiles.
5857
5858       "installvendorbin"
5859           From vendorbin.U:
5860
5861           This variable is really the same as vendorbinexp but may differ on
5862           those systems using "AFS". For extra portability, only this
5863           variable should be used in makefiles.
5864
5865       "installvendorhtml1dir"
5866           From vendorhtml1dir.U:
5867
5868           This variable is really the same as vendorhtml1direxp but may
5869           differ on those systems using "AFS". For extra portability, only
5870           this variable should be used in makefiles.
5871
5872       "installvendorhtml3dir"
5873           From vendorhtml3dir.U:
5874
5875           This variable is really the same as vendorhtml3direxp but may
5876           differ on those systems using "AFS". For extra portability, only
5877           this variable should be used in makefiles.
5878
5879       "installvendorlib"
5880           From vendorlib.U:
5881
5882           This variable is really the same as vendorlibexp but may differ on
5883           those systems using "AFS". For extra portability, only this
5884           variable should be used in makefiles.
5885
5886       "installvendorman1dir"
5887           From vendorman1dir.U:
5888
5889           This variable is really the same as vendorman1direxp but may differ
5890           on those systems using "AFS". For extra portability, only this
5891           variable should be used in makefiles.
5892
5893       "installvendorman3dir"
5894           From vendorman3dir.U:
5895
5896           This variable is really the same as vendorman3direxp but may differ
5897           on those systems using "AFS". For extra portability, only this
5898           variable should be used in makefiles.
5899
5900       "installvendorscript"
5901           From vendorscript.U:
5902
5903           This variable is really the same as vendorscriptexp but may differ
5904           on those systems using "AFS". For extra portability, only this
5905           variable should be used in makefiles.
5906
5907       "intsize"
5908           From intsize.U:
5909
5910           This variable contains the value of the "INTSIZE" symbol, which
5911           indicates to the C program how many bytes there are in an int.
5912
5913       "issymlink"
5914           From issymlink.U:
5915
5916           This variable holds the test command to test for a symbolic link
5917           (if they are supported).  Typical values include "test -h" and
5918           "test -L".
5919
5920       "ivdformat"
5921           From perlxvf.U:
5922
5923           This variable contains the format string used for printing a Perl
5924           "IV" as a signed decimal integer.
5925
5926       "ivsize"
5927           From perlxv.U:
5928
5929           This variable is the size of an "IV" in bytes.
5930
5931       "ivtype"
5932           From perlxv.U:
5933
5934           This variable contains the C type used for Perl's "IV".
5935
5936   k
5937       "known_extensions"
5938           From Extensions.U:
5939
5940           This variable holds a list of all extensions (both "XS" and non-xs)
5941           included in the package source distribution.  This information is
5942           only really of use during the Perl build, as the list makes no
5943           distinction between extensions which were build and installed, and
5944           those which where not.  See "extensions" for the list of extensions
5945           actually built and available.
5946
5947       "ksh"
5948           From Loc.U:
5949
5950           This variable is defined but not used by Configure.  The value is
5951           the empty string and is not useful.
5952
5953   l
5954       "ld"
5955           From dlsrc.U:
5956
5957           This variable indicates the program to be used to link libraries
5958           for dynamic loading.  On some systems, it is "ld".  On "ELF"
5959           systems, it should be $cc.  Mostly, we'll try to respect the hint
5960           file setting.
5961
5962       "ld_can_script"
5963           From dlsrc.U:
5964
5965           This variable shows if the loader accepts scripts in the form of
5966           -Wl,--version-script=ld.script. This is currently only supported
5967           for "GNU" ld on "ELF" in dynamic loading builds.
5968
5969       "lddlflags"
5970           From dlsrc.U:
5971
5972           This variable contains any special flags that might need to be
5973           passed to $ld to create a shared library suitable for dynamic
5974           loading.  It is up to the makefile to use it.  For hpux, it should
5975           be "-b".  For sunos 4.1, it is empty.
5976
5977       "ldflags"
5978           From ccflags.U:
5979
5980           This variable contains any additional C loader flags desired by the
5981           user.  It is up to the Makefile to use this.
5982
5983       "ldflags_uselargefiles"
5984           From uselfs.U:
5985
5986           This variable contains the loader flags needed by large file builds
5987           and added to ldflags by hints files.
5988
5989       "ldlibpthname"
5990           From libperl.U:
5991
5992           This variable holds the name of the shared library search path,
5993           often "LD_LIBRARY_PATH".  To get an empty string, the hints file
5994           must set this to "none".
5995
5996       "less"
5997           From Loc.U:
5998
5999           This variable is used internally by Configure to determine the full
6000           pathname (if any) of the less program.  After Configure runs, the
6001           value is reset to a plain "less" and is not useful.
6002
6003       "lib_ext"
6004           From Unix.U:
6005
6006           This is an old synonym for _a.
6007
6008       "libc"
6009           From libc.U:
6010
6011           This variable contains the location of the C library.
6012
6013       "libperl"
6014           From libperl.U:
6015
6016           The perl executable is obtained by linking perlmain.c with libperl,
6017           any static extensions (usually just DynaLoader), and any other
6018           libraries needed on this system.  libperl is usually libperl.a, but
6019           can also be libperl.so.xxx if the user wishes to build a perl
6020           executable with a shared library.
6021
6022       "libpth"
6023           From libpth.U:
6024
6025           This variable holds the general path (space-separated) used to find
6026           libraries. It is intended to be used by other units.
6027
6028       "libs"
6029           From libs.U:
6030
6031           This variable holds the additional libraries we want to use.  It is
6032           up to the Makefile to deal with it.  The list can be empty.
6033
6034       "libsdirs"
6035           From libs.U:
6036
6037           This variable holds the directory names aka dirnames of the
6038           libraries we found and accepted, duplicates are removed.
6039
6040       "libsfiles"
6041           From libs.U:
6042
6043           This variable holds the filenames aka basenames of the libraries we
6044           found and accepted.
6045
6046       "libsfound"
6047           From libs.U:
6048
6049           This variable holds the full pathnames of the libraries we found
6050           and accepted.
6051
6052       "libspath"
6053           From libs.U:
6054
6055           This variable holds the directory names probed for libraries.
6056
6057       "libswanted"
6058           From Myinit.U:
6059
6060           This variable holds a list of all the libraries we want to search.
6061           The order is chosen to pick up the c library ahead of ucb or bsd
6062           libraries for SVR4.
6063
6064       "libswanted_uselargefiles"
6065           From uselfs.U:
6066
6067           This variable contains the libraries needed by large file builds
6068           and added to ldflags by hints files.  It is a space separated list
6069           of the library names without the "lib" prefix or any suffix, just
6070           like libswanted..
6071
6072       "line"
6073           From Loc.U:
6074
6075           This variable is defined but not used by Configure.  The value is
6076           the empty string and is not useful.
6077
6078       "lint"
6079           From Loc.U:
6080
6081           This variable is defined but not used by Configure.  The value is
6082           the empty string and is not useful.
6083
6084       "lkflags"
6085           From ccflags.U:
6086
6087           This variable contains any additional C partial linker flags
6088           desired by the user.  It is up to the Makefile to use this.
6089
6090       "ln"
6091           From Loc.U:
6092
6093           This variable is used internally by Configure to determine the full
6094           pathname (if any) of the ln program.  After Configure runs, the
6095           value is reset to a plain "ln" and is not useful.
6096
6097       "lns"
6098           From lns.U:
6099
6100           This variable holds the name of the command to make symbolic links
6101           (if they are supported).  It can be used in the Makefile. It is
6102           either "ln -s" or "ln"
6103
6104       "localtime_r_proto"
6105           From d_localtime_r.U:
6106
6107           This variable encodes the prototype of localtime_r.  It is zero if
6108           d_localtime_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
6109           macros of reentr.h if d_localtime_r is defined.
6110
6111       "locincpth"
6112           From ccflags.U:
6113
6114           This variable contains a list of additional directories to be
6115           searched by the compiler.  The appropriate "-I" directives will be
6116           added to ccflags.  This is intended to simplify setting local
6117           directories from the Configure command line.  It's not much, but it
6118           parallels the loclibpth stuff in libpth.U.
6119
6120       "loclibpth"
6121           From libpth.U:
6122
6123           This variable holds the paths (space-separated) used to find local
6124           libraries.  It is prepended to libpth, and is intended to be easily
6125           set from the command line.
6126
6127       "longdblinfbytes"
6128           From infnan.U:
6129
6130           This variable contains comma-separated list of hexadecimal bytes
6131           for the long double precision infinity.
6132
6133       "longdblkind"
6134           From d_longdbl.U:
6135
6136           This variable, if defined, encodes the type of a long double: 0 =
6137           double, 1 = "IEEE" 754 128-bit little endian, 2 = "IEEE" 754
6138           128-bit big endian, 3 = x86 80-bit little endian, 4 = x86 80-bit
6139           big endian, 5 = double-double 128-bit little endian, 6 = double-
6140           double 128-bit big endian, 7 = 128-bit mixed-endian double-double
6141           (64-bit LEs in "BE"), 8 = 128-bit mixed-endian double-double
6142           (64-bit BEs in "LE"), 9 = 128-bit "PDP"-style mixed-endian long
6143           doubles, -1 = unknown format.
6144
6145       "longdblmantbits"
6146           From mantbits.U:
6147
6148           This symbol, if defined, tells how many mantissa bits there are in
6149           long double precision floating point format.  Note that this can be
6150           "LDBL_MANT_DIG" minus one, since "LDBL_MANT_DIG" can include the
6151           "IEEE" 754 implicit bit.  The common x86-style 80-bit long double
6152           does not have an implicit bit.
6153
6154       "longdblnanbytes"
6155           From infnan.U:
6156
6157           This variable contains comma-separated list of hexadecimal bytes
6158           for the long double precision not-a-number.
6159
6160       "longdblsize"
6161           From d_longdbl.U:
6162
6163           This variable contains the value of the "LONG_DOUBLESIZE" symbol,
6164           which indicates to the C program how many bytes there are in a long
6165           double, if this system supports long doubles.  Note that this is
6166           sizeof(long double), which may include unused bytes.
6167
6168       "longlongsize"
6169           From d_longlong.U:
6170
6171           This variable contains the value of the "LONGLONGSIZE" symbol,
6172           which indicates to the C program how many bytes there are in a long
6173           long, if this system supports long long.
6174
6175       "longsize"
6176           From intsize.U:
6177
6178           This variable contains the value of the "LONGSIZE" symbol, which
6179           indicates to the C program how many bytes there are in a long.
6180
6181       "lp"
6182           From Loc.U:
6183
6184           This variable is defined but not used by Configure.  The value is
6185           the empty string and is not useful.
6186
6187       "lpr"
6188           From Loc.U:
6189
6190           This variable is defined but not used by Configure.  The value is
6191           the empty string and is not useful.
6192
6193       "ls"
6194           From Loc.U:
6195
6196           This variable is used internally by Configure to determine the full
6197           pathname (if any) of the ls program.  After Configure runs, the
6198           value is reset to a plain "ls" and is not useful.
6199
6200       "lseeksize"
6201           From lseektype.U:
6202
6203           This variable defines lseektype to be something like off_t, long,
6204           or whatever type is used to declare lseek offset's type in the
6205           kernel (which also appears to be lseek's return type).
6206
6207       "lseektype"
6208           From lseektype.U:
6209
6210           This variable defines lseektype to be something like off_t, long,
6211           or whatever type is used to declare lseek offset's type in the
6212           kernel (which also appears to be lseek's return type).
6213
6214   m
6215       "mail"
6216           From Loc.U:
6217
6218           This variable is defined but not used by Configure.  The value is
6219           the empty string and is not useful.
6220
6221       "mailx"
6222           From Loc.U:
6223
6224           This variable is defined but not used by Configure.  The value is
6225           the empty string and is not useful.
6226
6227       "make"
6228           From Loc.U:
6229
6230           This variable is used internally by Configure to determine the full
6231           pathname (if any) of the make program.  After Configure runs, the
6232           value is reset to a plain "make" and is not useful.
6233
6234       "make_set_make"
6235           From make.U:
6236
6237           Some versions of "make" set the variable "MAKE".  Others do not.
6238           This variable contains the string to be included in Makefile.SH so
6239           that "MAKE" is set if needed, and not if not needed.  Possible
6240           values are:
6241
6242           make_set_make="#"        # If your make program handles this for
6243           you,
6244
6245           make_set_make="MAKE=$make"    # if it doesn't.
6246
6247           This uses a comment character so that we can distinguish a "set"
6248           value (from a previous config.sh or Configure "-D" option) from an
6249           uncomputed value.
6250
6251       "mallocobj"
6252           From mallocsrc.U:
6253
6254           This variable contains the name of the malloc.o that this package
6255           generates, if that malloc.o is preferred over the system malloc.
6256           Otherwise the value is null.  This variable is intended for
6257           generating Makefiles.  See mallocsrc.
6258
6259       "mallocsrc"
6260           From mallocsrc.U:
6261
6262           This variable contains the name of the malloc.c that comes with the
6263           package, if that malloc.c is preferred over the system malloc.
6264           Otherwise the value is null.  This variable is intended for
6265           generating Makefiles.
6266
6267       "malloctype"
6268           From mallocsrc.U:
6269
6270           This variable contains the kind of ptr returned by malloc and
6271           realloc.
6272
6273       "man1dir"
6274           From man1dir.U:
6275
6276           This variable contains the name of the directory in which manual
6277           source pages are to be put.  It is the responsibility of the
6278           Makefile.SH to get the value of this into the proper command.  You
6279           must be prepared to do the ~name expansion yourself.
6280
6281       "man1direxp"
6282           From man1dir.U:
6283
6284           This variable is the same as the man1dir variable, but is filename
6285           expanded at configuration time, for convenient use in makefiles.
6286
6287       "man1ext"
6288           From man1dir.U:
6289
6290           This variable contains the extension that the manual page should
6291           have: one of "n", "l", or 1.  The Makefile must supply the ..  See
6292           man1dir.
6293
6294       "man3dir"
6295           From man3dir.U:
6296
6297           This variable contains the name of the directory in which manual
6298           source pages are to be put.  It is the responsibility of the
6299           Makefile.SH to get the value of this into the proper command.  You
6300           must be prepared to do the ~name expansion yourself.
6301
6302       "man3direxp"
6303           From man3dir.U:
6304
6305           This variable is the same as the man3dir variable, but is filename
6306           expanded at configuration time, for convenient use in makefiles.
6307
6308       "man3ext"
6309           From man3dir.U:
6310
6311           This variable contains the extension that the manual page should
6312           have: one of "n", "l", or 3.  The Makefile must supply the ..  See
6313           man3dir.
6314
6315       "mips_type"
6316           From usrinc.U:
6317
6318           This variable holds the environment type for the mips system.
6319           Possible values are "BSD 4.3" and "System V".
6320
6321       "mistrustnm"
6322           From Csym.U:
6323
6324           This variable can be used to establish a fallthrough for the cases
6325           where nm fails to find a symbol.  If usenm is false or usenm is
6326           true and mistrustnm is false, this variable has no effect.  If
6327           usenm is true and mistrustnm is "compile", a test program will be
6328           compiled to try to find any symbol that can't be located via nm
6329           lookup.  If mistrustnm is "run", the test program will be run as
6330           well as being compiled.
6331
6332       "mkdir"
6333           From Loc.U:
6334
6335           This variable is used internally by Configure to determine the full
6336           pathname (if any) of the mkdir program.  After Configure runs, the
6337           value is reset to a plain "mkdir" and is not useful.
6338
6339       "mmaptype"
6340           From d_mmap.U:
6341
6342           This symbol contains the type of pointer returned by mmap() (and
6343           simultaneously the type of the first argument).  It can be "void *"
6344           or "caddr_t".
6345
6346       "modetype"
6347           From modetype.U:
6348
6349           This variable defines modetype to be something like mode_t, int,
6350           unsigned short, or whatever type is used to declare file modes for
6351           system calls.
6352
6353       "more"
6354           From Loc.U:
6355
6356           This variable is used internally by Configure to determine the full
6357           pathname (if any) of the more program.  After Configure runs, the
6358           value is reset to a plain "more" and is not useful.
6359
6360       "multiarch"
6361           From multiarch.U:
6362
6363           This variable conditionally defines the "MULTIARCH" symbol which
6364           signifies the presence of multiplatform files.  This is normally
6365           set by hints files.
6366
6367       "mv"
6368           From Loc.U:
6369
6370           This variable is defined but not used by Configure.  The value is
6371           the empty string and is not useful.
6372
6373       "myarchname"
6374           From archname.U:
6375
6376           This variable holds the architecture name computed by Configure in
6377           a previous run. It is not intended to be perused by any user and
6378           should never be set in a hint file.
6379
6380       "mydomain"
6381           From myhostname.U:
6382
6383           This variable contains the eventual value of the "MYDOMAIN" symbol,
6384           which is the domain of the host the program is going to run on.
6385           The domain must be appended to myhostname to form a complete host
6386           name.  The dot comes with mydomain, and need not be supplied by the
6387           program.
6388
6389       "myhostname"
6390           From myhostname.U:
6391
6392           This variable contains the eventual value of the "MYHOSTNAME"
6393           symbol, which is the name of the host the program is going to run
6394           on.  The domain is not kept with hostname, but must be gotten from
6395           mydomain.  The dot comes with mydomain, and need not be supplied by
6396           the program.
6397
6398       "myuname"
6399           From Oldconfig.U:
6400
6401           The output of "uname -a" if available, otherwise the hostname.  The
6402           whole thing is then lower-cased and slashes and single quotes are
6403           removed.
6404
6405   n
6406       "n" From n.U:
6407
6408           This variable contains the "-n" flag if that is what causes the
6409           echo command to suppress newline.  Otherwise it is null.  Correct
6410           usage is $echo $n "prompt for a question: $c".
6411
6412       "need_va_copy"
6413           From need_va_copy.U:
6414
6415           This symbol, if defined, indicates that the system stores the
6416           variable argument list datatype, va_list, in a format that cannot
6417           be copied by simple assignment, so that some other means must be
6418           used when copying is required.  As such systems vary in their
6419           provision (or non-provision) of copying mechanisms, handy.h defines
6420           a platform- "independent" macro, Perl_va_copy(src, dst), to do the
6421           job.
6422
6423       "netdb_hlen_type"
6424           From netdbtype.U:
6425
6426           This variable holds the type used for the 2nd argument to
6427           gethostbyaddr().  Usually, this is int or size_t or unsigned.  This
6428           is only useful if you have gethostbyaddr(), naturally.
6429
6430       "netdb_host_type"
6431           From netdbtype.U:
6432
6433           This variable holds the type used for the 1st argument to
6434           gethostbyaddr().  Usually, this is char * or void *,  possibly with
6435           or without a const prefix.  This is only useful if you have
6436           gethostbyaddr(), naturally.
6437
6438       "netdb_name_type"
6439           From netdbtype.U:
6440
6441           This variable holds the type used for the argument to
6442           gethostbyname().  Usually, this is char * or const char *.  This is
6443           only useful if you have gethostbyname(), naturally.
6444
6445       "netdb_net_type"
6446           From netdbtype.U:
6447
6448           This variable holds the type used for the 1st argument to
6449           getnetbyaddr().  Usually, this is int or long.  This is only useful
6450           if you have getnetbyaddr(), naturally.
6451
6452       "nm"
6453           From Loc.U:
6454
6455           This variable is used internally by Configure to determine the full
6456           pathname (if any) of the nm program.  After Configure runs, the
6457           value is reset to a plain "nm" and is not useful.
6458
6459       "nm_opt"
6460           From usenm.U:
6461
6462           This variable holds the options that may be necessary for nm.
6463
6464       "nm_so_opt"
6465           From usenm.U:
6466
6467           This variable holds the options that may be necessary for nm to
6468           work on a shared library but that can not be used on an archive
6469           library.  Currently, this is only used by Linux, where nm --dynamic
6470           is *required* to get symbols from an "ELF" library which has been
6471           stripped, but nm --dynamic is *fatal* on an archive library.  Maybe
6472           Linux should just always set usenm=false.
6473
6474       "nonxs_ext"
6475           From Extensions.U:
6476
6477           This variable holds a list of all non-xs extensions built and
6478           installed by the package.  By default, all non-xs extensions
6479           distributed will be built, with the exception of platform-specific
6480           extensions (currently only one "VMS" specific extension).
6481
6482       "nroff"
6483           From Loc.U:
6484
6485           This variable is used internally by Configure to determine the full
6486           pathname (if any) of the nroff program.  After Configure runs, the
6487           value is reset to a plain "nroff" and is not useful.
6488
6489       "nv_overflows_integers_at"
6490           From perlxv.U:
6491
6492           This variable gives the largest integer value that NVs can hold as
6493           a constant floating point expression.  If it could not be
6494           determined, it holds the value 0.
6495
6496       "nv_preserves_uv_bits"
6497           From perlxv.U:
6498
6499           This variable indicates how many of bits type uvtype a variable
6500           nvtype can preserve.
6501
6502       "nveformat"
6503           From perlxvf.U:
6504
6505           This variable contains the format string used for printing a Perl
6506           "NV" using %e-ish floating point format.
6507
6508       "nvEUformat"
6509           From perlxvf.U:
6510
6511           This variable contains the format string used for printing a Perl
6512           "NV" using %E-ish floating point format.
6513
6514       "nvfformat"
6515           From perlxvf.U:
6516
6517           This variable contains the format string used for printing a Perl
6518           "NV" using %f-ish floating point format.
6519
6520       "nvFUformat"
6521           From perlxvf.U:
6522
6523           This variable contains the format string used for printing a Perl
6524           "NV" using %F-ish floating point format.
6525
6526       "nvgformat"
6527           From perlxvf.U:
6528
6529           This variable contains the format string used for printing a Perl
6530           "NV" using %g-ish floating point format.
6531
6532       "nvGUformat"
6533           From perlxvf.U:
6534
6535           This variable contains the format string used for printing a Perl
6536           "NV" using %G-ish floating point format.
6537
6538       "nvmantbits"
6539           From mantbits.U:
6540
6541           This variable tells how many bits the mantissa of a Perl "NV" has,
6542           not including the possible implicit bit.
6543
6544       "nvsize"
6545           From perlxv.U:
6546
6547           This variable is the size of a Perl "NV" in bytes.  Note that some
6548           floating point formats have unused bytes.
6549
6550       "nvtype"
6551           From perlxv.U:
6552
6553           This variable contains the C type used for Perl's "NV".
6554
6555   o
6556       "o_nonblock"
6557           From nblock_io.U:
6558
6559           This variable bears the symbol value to be used during open() or
6560           fcntl() to turn on non-blocking I/O for a file descriptor. If you
6561           wish to switch between blocking and non-blocking, you may try
6562           ioctl("FIOSNBIO") instead, but that is only supported by some
6563           devices.
6564
6565       "obj_ext"
6566           From Unix.U:
6567
6568           This is an old synonym for _o.
6569
6570       "old_pthread_create_joinable"
6571           From d_pthrattrj.U:
6572
6573           This variable defines the constant to use for creating joinable
6574           (aka undetached) pthreads.  Unused if pthread.h defines
6575           "PTHREAD_CREATE_JOINABLE".  If used, possible values are
6576           "PTHREAD_CREATE_UNDETACHED" and "__UNDETACHED".
6577
6578       "optimize"
6579           From ccflags.U:
6580
6581           This variable contains any optimizer/debugger flag that should be
6582           used.  It is up to the Makefile to use it.
6583
6584       "orderlib"
6585           From orderlib.U:
6586
6587           This variable is "true" if the components of libraries must be
6588           ordered (with `lorder $* | tsort`) before placing them in an
6589           archive.  Set to "false" if ranlib or ar can generate random
6590           libraries.
6591
6592       "osname"
6593           From Oldconfig.U:
6594
6595           This variable contains the operating system name (e.g. sunos,
6596           solaris, hpux, etc.).  It can be useful later on for setting
6597           defaults.  Any spaces are replaced with underscores.  It is set to
6598           a null string if we can't figure it out.
6599
6600       "osvers"
6601           From Oldconfig.U:
6602
6603           This variable contains the operating system version (e.g.  4.1.3,
6604           5.2, etc.).  It is primarily used for helping select an appropriate
6605           hints file, but might be useful elsewhere for setting defaults.  It
6606           is set to '' if we can't figure it out.  We try to be flexible
6607           about how much of the version number to keep, e.g. if 4.1.1, 4.1.2,
6608           and 4.1.3 are essentially the same for this package, hints files
6609           might just be os_4.0 or os_4.1, etc., not keeping separate files
6610           for each little release.
6611
6612       "otherlibdirs"
6613           From otherlibdirs.U:
6614
6615           This variable contains a colon-separated set of paths for the perl
6616           binary to search for additional library files or modules.  These
6617           directories will be tacked to the end of @"INC".  Perl will
6618           automatically search below each path for version- and architecture-
6619           specific directories.  See inc_version_list for more details.  A
6620           value of " " means "none" and is used to preserve this value for
6621           the next run through Configure.
6622
6623   p
6624       "package"
6625           From package.U:
6626
6627           This variable contains the name of the package being constructed.
6628           It is primarily intended for the use of later Configure units.
6629
6630       "pager"
6631           From pager.U:
6632
6633           This variable contains the name of the preferred pager on the
6634           system.  Usual values are (the full pathnames of) more, less, pg,
6635           or cat.
6636
6637       "passcat"
6638           From nis.U:
6639
6640           This variable contains a command that produces the text of the
6641           /etc/passwd file.  This is normally "cat /etc/passwd", but can be
6642           "ypcat passwd" when "NIS" is used.  On some systems, such as os390,
6643           there may be no equivalent command, in which case this variable is
6644           unset.
6645
6646       "patchlevel"
6647           From patchlevel.U:
6648
6649           The patchlevel level of this package.  The value of patchlevel
6650           comes from the patchlevel.h file.  In a version number such as
6651           5.6.1, this is the 6.  In patchlevel.h, this is referred to as
6652           "PERL_VERSION".
6653
6654       "path_sep"
6655           From Unix.U:
6656
6657           This is an old synonym for p_ in Head.U, the character used to
6658           separate elements in the command shell search "PATH".
6659
6660       "perl"
6661           From Loc.U:
6662
6663           This variable is used internally by Configure to determine the full
6664           pathname (if any) of the perl program.  After Configure runs, the
6665           value is reset to a plain "perl" and is not useful.
6666
6667       "perl5"
6668           From perl5.U:
6669
6670           This variable contains the full path (if any) to a previously
6671           installed perl5.005 or later suitable for running the script to
6672           determine inc_version_list.
6673
6674   P
6675       "PERL_API_REVISION"
6676           From patchlevel.h:
6677
6678           This number describes the earliest compatible "PERL_REVISION" of
6679           Perl ("compatibility" here being defined as sufficient binary/"API"
6680           compatibility to run "XS" code built with the older version).
6681           Normally this does not change across maintenance releases.  Please
6682           read the comment in patchlevel.h.
6683
6684       "PERL_API_SUBVERSION"
6685           From patchlevel.h:
6686
6687           This number describes the earliest compatible "PERL_SUBVERSION" of
6688           Perl ("compatibility" here being defined as sufficient binary/"API"
6689           compatibility to run "XS" code built with the older version).
6690           Normally this does not change across maintenance releases.  Please
6691           read the comment in patchlevel.h.
6692
6693       "PERL_API_VERSION"
6694           From patchlevel.h:
6695
6696           This number describes the earliest compatible "PERL_VERSION" of
6697           Perl ("compatibility" here being defined as sufficient binary/"API"
6698           compatibility to run "XS" code built with the older version).
6699           Normally this does not change across maintenance releases.  Please
6700           read the comment in patchlevel.h.
6701
6702       "PERL_CONFIG_SH"
6703           From Oldsyms.U:
6704
6705           This is set to "true" in config.sh so that a shell script sourcing
6706           config.sh can tell if it has been sourced already.
6707
6708       "PERL_PATCHLEVEL"
6709           From Oldsyms.U:
6710
6711           This symbol reflects the patchlevel, if available. Will usually
6712           come from the .patch file, which is available when the perl source
6713           tree was fetched with rsync.
6714
6715       "perl_patchlevel"
6716           From patchlevel.U:
6717
6718           This is the Perl patch level, a numeric change identifier, as
6719           defined by whichever source code maintenance system is used to
6720           maintain the patches; currently Perforce.  It does not correlate
6721           with the Perl version numbers or the maintenance versus development
6722           dichotomy except by also being increasing.
6723
6724       "PERL_REVISION"
6725           From Oldsyms.U:
6726
6727           In a Perl version number such as 5.6.2, this is the 5.  This value
6728           is manually set in patchlevel.h
6729
6730       "perl_static_inline"
6731           From d_static_inline.U:
6732
6733           This variable defines the "PERL_STATIC_INLINE" symbol to the best-
6734           guess incantation to use for static inline functions.
6735           Possibilities include static inline       (c99) static __inline__
6736           (gcc -ansi) static __inline     ("MSVC") static _inline      (older
6737           "MSVC") static              (c89 compilers)
6738
6739       "PERL_SUBVERSION"
6740           From Oldsyms.U:
6741
6742           In a Perl version number such as 5.6.2, this is the 2.  Values
6743           greater than 50 represent potentially unstable development
6744           subversions.  This value is manually set in patchlevel.h
6745
6746       "PERL_VERSION"
6747           From Oldsyms.U:
6748
6749           In a Perl version number such as 5.6.2, this is the 6.  This value
6750           is manually set in patchlevel.h
6751
6752       "perladmin"
6753           From perladmin.U:
6754
6755           Electronic mail address of the perl5 administrator.
6756
6757       "perllibs"
6758           From End.U:
6759
6760           The list of libraries needed by Perl only (any libraries needed by
6761           extensions only will by dropped, if using dynamic loading).
6762
6763       "perlpath"
6764           From perlpath.U:
6765
6766           This variable contains the eventual value of the "PERLPATH" symbol,
6767           which contains the name of the perl interpreter to be used in shell
6768           scripts and in the "eval "exec"" idiom.  This variable is not
6769           necessarily the pathname of the file containing the perl
6770           interpreter; you must append the executable extension (_exe) if it
6771           is not already present.  Note that Perl code that runs during the
6772           Perl build process cannot reference this variable, as Perl may not
6773           have been installed, or even if installed, may be a different
6774           version of Perl.
6775
6776       "pg"
6777           From Loc.U:
6778
6779           This variable is used internally by Configure to determine the full
6780           pathname (if any) of the pg program.  After Configure runs, the
6781           value is reset to a plain "pg" and is not useful.
6782
6783       "phostname"
6784           From myhostname.U:
6785
6786           This variable contains the eventual value of the "PHOSTNAME"
6787           symbol, which is a command that can be fed to popen() to get the
6788           host name.  The program should probably not presume that the domain
6789           is or isn't there already.
6790
6791       "pidtype"
6792           From pidtype.U:
6793
6794           This variable defines "PIDTYPE" to be something like pid_t, int,
6795           ushort, or whatever type is used to declare process ids in the
6796           kernel.
6797
6798       "plibpth"
6799           From libpth.U:
6800
6801           Holds the private path used by Configure to find out the libraries.
6802           Its value is prepend to libpth. This variable takes care of special
6803           machines, like the mips.  Usually, it should be empty.
6804
6805       "pmake"
6806           From Loc.U:
6807
6808           This variable is defined but not used by Configure.  The value is
6809           the empty string and is not useful.
6810
6811       "pr"
6812           From Loc.U:
6813
6814           This variable is defined but not used by Configure.  The value is
6815           the empty string and is not useful.
6816
6817       "prefix"
6818           From prefix.U:
6819
6820           This variable holds the name of the directory below which the user
6821           will install the package.  Usually, this is /usr/local, and
6822           executables go in /usr/local/bin, library stuff in /usr/local/lib,
6823           man pages in /usr/local/man, etc.  It is only used to set defaults
6824           for things in bin.U, mansrc.U, privlib.U, or scriptdir.U.
6825
6826       "prefixexp"
6827           From prefix.U:
6828
6829           This variable holds the full absolute path of the directory below
6830           which the user will install the package.  Derived from prefix.
6831
6832       "privlib"
6833           From privlib.U:
6834
6835           This variable contains the eventual value of the "PRIVLIB" symbol,
6836           which is the name of the private library for this package.  It may
6837           have a ~ on the front. It is up to the makefile to eventually
6838           create this directory while performing installation (with ~
6839           substitution).
6840
6841       "privlibexp"
6842           From privlib.U:
6843
6844           This variable is the ~name expanded version of privlib, so that you
6845           may use it directly in Makefiles or shell scripts.
6846
6847       "procselfexe"
6848           From d_procselfexe.U:
6849
6850           If d_procselfexe is defined, $procselfexe is the filename of the
6851           symbolic link pointing to the absolute pathname of the executing
6852           program.
6853
6854       "ptrsize"
6855           From ptrsize.U:
6856
6857           This variable contains the value of the "PTRSIZE" symbol, which
6858           indicates to the C program how many bytes there are in a pointer.
6859
6860   q
6861       "quadkind"
6862           From quadtype.U:
6863
6864           This variable, if defined, encodes the type of a quad: 1 = int, 2 =
6865           long, 3 = long long, 4 = int64_t.
6866
6867       "quadtype"
6868           From quadtype.U:
6869
6870           This variable defines Quad_t to be something like long, int, long
6871           long, int64_t, or whatever type is used for 64-bit integers.
6872
6873   r
6874       "randbits"
6875           From randfunc.U:
6876
6877           Indicates how many bits are produced by the function used to
6878           generate normalized random numbers.
6879
6880       "randfunc"
6881           From randfunc.U:
6882
6883           Indicates the name of the random number function to use.  Values
6884           include drand48, random, and rand. In C programs, the "Drand01"
6885           macro is defined to generate uniformly distributed random numbers
6886           over the range [0., 1.[ (see drand01 and nrand).
6887
6888       "random_r_proto"
6889           From d_random_r.U:
6890
6891           This variable encodes the prototype of random_r.  It is zero if
6892           d_random_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
6893           of reentr.h if d_random_r is defined.
6894
6895       "randseedtype"
6896           From randfunc.U:
6897
6898           Indicates the type of the argument of the seedfunc.
6899
6900       "ranlib"
6901           From orderlib.U:
6902
6903           This variable is set to the pathname of the ranlib program, if it
6904           is needed to generate random libraries.  Set to ":" if ar can
6905           generate random libraries or if random libraries are not supported
6906
6907       "rd_nodata"
6908           From nblock_io.U:
6909
6910           This variable holds the return code from read() when no data is
6911           present. It should be -1, but some systems return 0 when "O_NDELAY"
6912           is used, which is a shame because you cannot make the difference
6913           between no data and an EOF.. Sigh!
6914
6915       "readdir64_r_proto"
6916           From d_readdir64_r.U:
6917
6918           This variable encodes the prototype of readdir64_r.  It is zero if
6919           d_readdir64_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
6920           macros of reentr.h if d_readdir64_r is defined.
6921
6922       "readdir_r_proto"
6923           From d_readdir_r.U:
6924
6925           This variable encodes the prototype of readdir_r.  It is zero if
6926           d_readdir_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
6927           of reentr.h if d_readdir_r is defined.
6928
6929       "revision"
6930           From patchlevel.U:
6931
6932           The value of revision comes from the patchlevel.h file.  In a
6933           version number such as 5.6.1, this is the 5.  In patchlevel.h, this
6934           is referred to as "PERL_REVISION".
6935
6936       "rm"
6937           From Loc.U:
6938
6939           This variable is used internally by Configure to determine the full
6940           pathname (if any) of the rm program.  After Configure runs, the
6941           value is reset to a plain "rm" and is not useful.
6942
6943       "rm_try"
6944           From Unix.U:
6945
6946           This is a cleanup variable for try test programs.  Internal
6947           Configure use only.
6948
6949       "rmail"
6950           From Loc.U:
6951
6952           This variable is defined but not used by Configure.  The value is
6953           the empty string and is not useful.
6954
6955       "run"
6956           From Cross.U:
6957
6958           This variable contains the command used by Configure to copy and
6959           execute a cross-compiled executable in the target host.  Useful and
6960           available only during Perl build.  Empty string '' if not cross-
6961           compiling.
6962
6963       "runnm"
6964           From usenm.U:
6965
6966           This variable contains "true" or "false" depending whether the nm
6967           extraction should be performed or not, according to the value of
6968           usenm and the flags on the Configure command line.
6969
6970   s
6971       "sched_yield"
6972           From d_pthread_y.U:
6973
6974           This variable defines the way to yield the execution of the current
6975           thread.
6976
6977       "scriptdir"
6978           From scriptdir.U:
6979
6980           This variable holds the name of the directory in which the user
6981           wants to put publicly scripts for the package in question.  It is
6982           either the same directory as for binaries, or a special one that
6983           can be mounted across different architectures, like /usr/share.
6984           Programs must be prepared to deal with ~name expansion.
6985
6986       "scriptdirexp"
6987           From scriptdir.U:
6988
6989           This variable is the same as scriptdir, but is filename expanded at
6990           configuration time, for programs not wanting to bother with it.
6991
6992       "sed"
6993           From Loc.U:
6994
6995           This variable is used internally by Configure to determine the full
6996           pathname (if any) of the sed program.  After Configure runs, the
6997           value is reset to a plain "sed" and is not useful.
6998
6999       "seedfunc"
7000           From randfunc.U:
7001
7002           Indicates the random number generating seed function.  Values
7003           include srand48, srandom, and srand.
7004
7005       "selectminbits"
7006           From selectminbits.U:
7007
7008           This variable holds the minimum number of bits operated by select.
7009           That is, if you do select(n, ...), how many bits at least will be
7010           cleared in the masks if some activity is detected.  Usually this is
7011           either n or 32*ceil(n/32), especially many little-endians do the
7012           latter.  This is only useful if you have select(), naturally.
7013
7014       "selecttype"
7015           From selecttype.U:
7016
7017           This variable holds the type used for the 2nd, 3rd, and 4th
7018           arguments to select.  Usually, this is "fd_set *", if "HAS_FD_SET"
7019           is defined, and "int *" otherwise.  This is only useful if you have
7020           select(), naturally.
7021
7022       "sendmail"
7023           From Loc.U:
7024
7025           This variable is defined but not used by Configure.  The value is
7026           the empty string and is not useful.
7027
7028       "setgrent_r_proto"
7029           From d_setgrent_r.U:
7030
7031           This variable encodes the prototype of setgrent_r.  It is zero if
7032           d_setgrent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
7033           macros of reentr.h if d_setgrent_r is defined.
7034
7035       "sethostent_r_proto"
7036           From d_sethostent_r.U:
7037
7038           This variable encodes the prototype of sethostent_r.  It is zero if
7039           d_sethostent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
7040           macros of reentr.h if d_sethostent_r is defined.
7041
7042       "setlocale_r_proto"
7043           From d_setlocale_r.U:
7044
7045           This variable encodes the prototype of setlocale_r.  It is zero if
7046           d_setlocale_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
7047           macros of reentr.h if d_setlocale_r is defined.
7048
7049       "setnetent_r_proto"
7050           From d_setnetent_r.U:
7051
7052           This variable encodes the prototype of setnetent_r.  It is zero if
7053           d_setnetent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
7054           macros of reentr.h if d_setnetent_r is defined.
7055
7056       "setprotoent_r_proto"
7057           From d_setprotoent_r.U:
7058
7059           This variable encodes the prototype of setprotoent_r.  It is zero
7060           if d_setprotoent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
7061           macros of reentr.h if d_setprotoent_r is defined.
7062
7063       "setpwent_r_proto"
7064           From d_setpwent_r.U:
7065
7066           This variable encodes the prototype of setpwent_r.  It is zero if
7067           d_setpwent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
7068           macros of reentr.h if d_setpwent_r is defined.
7069
7070       "setservent_r_proto"
7071           From d_setservent_r.U:
7072
7073           This variable encodes the prototype of setservent_r.  It is zero if
7074           d_setservent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
7075           macros of reentr.h if d_setservent_r is defined.
7076
7077       "sGMTIME_max"
7078           From time_size.U:
7079
7080           This variable defines the maximum value of the time_t offset that
7081           the system function gmtime () accepts
7082
7083       "sGMTIME_min"
7084           From time_size.U:
7085
7086           This variable defines the minimum value of the time_t offset that
7087           the system function gmtime () accepts
7088
7089       "sh"
7090           From sh.U:
7091
7092           This variable contains the full pathname of the shell used on this
7093           system to execute Bourne shell scripts.  Usually, this will be
7094           /bin/sh, though it's possible that some systems will have /bin/ksh,
7095           /bin/pdksh, /bin/ash, /bin/bash, or even something such as
7096           D:/bin/sh.exe.  This unit comes before Options.U, so you can't set
7097           sh with a "-D" option, though you can override this (and startsh)
7098           with "-O -Dsh=/bin/whatever -Dstartsh=whatever"
7099
7100       "shar"
7101           From Loc.U:
7102
7103           This variable is defined but not used by Configure.  The value is
7104           the empty string and is not useful.
7105
7106       "sharpbang"
7107           From spitshell.U:
7108
7109           This variable contains the string #! if this system supports that
7110           construct.
7111
7112       "shmattype"
7113           From d_shmat.U:
7114
7115           This symbol contains the type of pointer returned by shmat().  It
7116           can be "void *" or "char *".
7117
7118       "shortsize"
7119           From intsize.U:
7120
7121           This variable contains the value of the "SHORTSIZE" symbol which
7122           indicates to the C program how many bytes there are in a short.
7123
7124       "shrpenv"
7125           From libperl.U:
7126
7127           If the user builds a shared libperl.so, then we need to tell the
7128           "perl" executable where it will be able to find the installed
7129           libperl.so.  One way to do this on some systems is to set the
7130           environment variable "LD_RUN_PATH" to the directory that will be
7131           the final location of the shared libperl.so.  The makefile can use
7132           this with something like $shrpenv $("CC") -o perl perlmain.o
7133           $libperl $libs Typical values are shrpenv="env
7134           "LD_RUN_PATH"=$archlibexp/"CORE"" or shrpenv='' See the main perl
7135           Makefile.SH for actual working usage.
7136
7137           Alternatively, we might be able to use a command line option such
7138           as -R $archlibexp/"CORE" (Solaris) or -Wl,-rpath $archlibexp/"CORE"
7139           (Linux).
7140
7141       "shsharp"
7142           From spitshell.U:
7143
7144           This variable tells further Configure units whether your sh can
7145           handle # comments.
7146
7147       "sig_count"
7148           From sig_name.U:
7149
7150           This variable holds a number larger than the largest valid signal
7151           number.  This is usually the same as the "NSIG" macro.
7152
7153       "sig_name"
7154           From sig_name.U:
7155
7156           This variable holds the signal names, space separated. The leading
7157           "SIG" in signal name is removed.  A "ZERO" is prepended to the
7158           list.  This is currently not used, sig_name_init is used instead.
7159
7160       "sig_name_init"
7161           From sig_name.U:
7162
7163           This variable holds the signal names, enclosed in double quotes and
7164           separated by commas, suitable for use in the "SIG_NAME" definition
7165           below.  A "ZERO" is prepended to the list, and the list is
7166           terminated with a plain 0.  The leading "SIG" in signal names is
7167           removed. See sig_num.
7168
7169       "sig_num"
7170           From sig_name.U:
7171
7172           This variable holds the signal numbers, space separated. A "ZERO"
7173           is prepended to the list (corresponding to the fake "SIGZERO").
7174           Those numbers correspond to  the value of the signal listed in the
7175           same place within the sig_name list.  This is currently not used,
7176           sig_num_init is used instead.
7177
7178       "sig_num_init"
7179           From sig_name.U:
7180
7181           This variable holds the signal numbers, enclosed in double quotes
7182           and separated by commas, suitable for use in the "SIG_NUM"
7183           definition below.  A "ZERO" is prepended to the list, and the list
7184           is terminated with a plain 0.
7185
7186       "sig_size"
7187           From sig_name.U:
7188
7189           This variable contains the number of elements of the sig_name and
7190           sig_num arrays.
7191
7192       "signal_t"
7193           From d_voidsig.U:
7194
7195           This variable holds the type of the signal handler (void or int).
7196
7197       "sitearch"
7198           From sitearch.U:
7199
7200           This variable contains the eventual value of the "SITEARCH" symbol,
7201           which is the name of the private library for this package.  It may
7202           have a ~ on the front. It is up to the makefile to eventually
7203           create this directory while performing installation (with ~
7204           substitution).  The standard distribution will put nothing in this
7205           directory.  After perl has been installed, users may install their
7206           own local architecture-dependent modules in this directory with
7207           MakeMaker Makefile.PL or equivalent.  See "INSTALL" for details.
7208
7209       "sitearchexp"
7210           From sitearch.U:
7211
7212           This variable is the ~name expanded version of sitearch, so that
7213           you may use it directly in Makefiles or shell scripts.
7214
7215       "sitebin"
7216           From sitebin.U:
7217
7218           This variable holds the name of the directory in which the user
7219           wants to put add-on publicly executable files for the package in
7220           question.  It is most often a local directory such as
7221           /usr/local/bin. Programs using this variable must be prepared to
7222           deal with ~name substitution.  The standard distribution will put
7223           nothing in this directory.  After perl has been installed, users
7224           may install their own local executables in this directory with
7225           MakeMaker Makefile.PL or equivalent.  See "INSTALL" for details.
7226
7227       "sitebinexp"
7228           From sitebin.U:
7229
7230           This is the same as the sitebin variable, but is filename expanded
7231           at configuration time, for use in your makefiles.
7232
7233       "sitehtml1dir"
7234           From sitehtml1dir.U:
7235
7236           This variable contains the name of the directory in which site-
7237           specific html source pages are to be put.  It is the responsibility
7238           of the Makefile.SH to get the value of this into the proper
7239           command.  You must be prepared to do the ~name expansion yourself.
7240           The standard distribution will put nothing in this directory.
7241           After perl has been installed, users may install their own local
7242           html pages in this directory with MakeMaker Makefile.PL or
7243           equivalent.  See "INSTALL" for details.
7244
7245       "sitehtml1direxp"
7246           From sitehtml1dir.U:
7247
7248           This variable is the same as the sitehtml1dir variable, but is
7249           filename expanded at configuration time, for convenient use in
7250           makefiles.
7251
7252       "sitehtml3dir"
7253           From sitehtml3dir.U:
7254
7255           This variable contains the name of the directory in which site-
7256           specific library html source pages are to be put.  It is the
7257           responsibility of the Makefile.SH to get the value of this into the
7258           proper command.  You must be prepared to do the ~name expansion
7259           yourself.  The standard distribution will put nothing in this
7260           directory.  After perl has been installed, users may install their
7261           own local library html pages in this directory with MakeMaker
7262           Makefile.PL or equivalent.  See "INSTALL" for details.
7263
7264       "sitehtml3direxp"
7265           From sitehtml3dir.U:
7266
7267           This variable is the same as the sitehtml3dir variable, but is
7268           filename expanded at configuration time, for convenient use in
7269           makefiles.
7270
7271       "sitelib"
7272           From sitelib.U:
7273
7274           This variable contains the eventual value of the "SITELIB" symbol,
7275           which is the name of the private library for this package.  It may
7276           have a ~ on the front. It is up to the makefile to eventually
7277           create this directory while performing installation (with ~
7278           substitution).  The standard distribution will put nothing in this
7279           directory.  After perl has been installed, users may install their
7280           own local architecture-independent modules in this directory with
7281           MakeMaker Makefile.PL or equivalent.  See "INSTALL" for details.
7282
7283       "sitelib_stem"
7284           From sitelib.U:
7285
7286           This variable is $sitelibexp with any trailing version-specific
7287           component removed.  The elements in inc_version_list
7288           (inc_version_list.U) can be tacked onto this variable to generate a
7289           list of directories to search.
7290
7291       "sitelibexp"
7292           From sitelib.U:
7293
7294           This variable is the ~name expanded version of sitelib, so that you
7295           may use it directly in Makefiles or shell scripts.
7296
7297       "siteman1dir"
7298           From siteman1dir.U:
7299
7300           This variable contains the name of the directory in which site-
7301           specific manual source pages are to be put.  It is the
7302           responsibility of the Makefile.SH to get the value of this into the
7303           proper command.  You must be prepared to do the ~name expansion
7304           yourself.  The standard distribution will put nothing in this
7305           directory.  After perl has been installed, users may install their
7306           own local man1 pages in this directory with MakeMaker Makefile.PL
7307           or equivalent.  See "INSTALL" for details.
7308
7309       "siteman1direxp"
7310           From siteman1dir.U:
7311
7312           This variable is the same as the siteman1dir variable, but is
7313           filename expanded at configuration time, for convenient use in
7314           makefiles.
7315
7316       "siteman3dir"
7317           From siteman3dir.U:
7318
7319           This variable contains the name of the directory in which site-
7320           specific library man source pages are to be put.  It is the
7321           responsibility of the Makefile.SH to get the value of this into the
7322           proper command.  You must be prepared to do the ~name expansion
7323           yourself.  The standard distribution will put nothing in this
7324           directory.  After perl has been installed, users may install their
7325           own local man3 pages in this directory with MakeMaker Makefile.PL
7326           or equivalent.  See "INSTALL" for details.
7327
7328       "siteman3direxp"
7329           From siteman3dir.U:
7330
7331           This variable is the same as the siteman3dir variable, but is
7332           filename expanded at configuration time, for convenient use in
7333           makefiles.
7334
7335       "siteprefix"
7336           From siteprefix.U:
7337
7338           This variable holds the full absolute path of the directory below
7339           which the user will install add-on packages.  See "INSTALL" for
7340           usage and examples.
7341
7342       "siteprefixexp"
7343           From siteprefix.U:
7344
7345           This variable holds the full absolute path of the directory below
7346           which the user will install add-on packages.  Derived from
7347           siteprefix.
7348
7349       "sitescript"
7350           From sitescript.U:
7351
7352           This variable holds the name of the directory in which the user
7353           wants to put add-on publicly executable files for the package in
7354           question.  It is most often a local directory such as
7355           /usr/local/bin. Programs using this variable must be prepared to
7356           deal with ~name substitution.  The standard distribution will put
7357           nothing in this directory.  After perl has been installed, users
7358           may install their own local scripts in this directory with
7359           MakeMaker Makefile.PL or equivalent.  See "INSTALL" for details.
7360
7361       "sitescriptexp"
7362           From sitescript.U:
7363
7364           This is the same as the sitescript variable, but is filename
7365           expanded at configuration time, for use in your makefiles.
7366
7367       "sizesize"
7368           From sizesize.U:
7369
7370           This variable contains the size of a sizetype in bytes.
7371
7372       "sizetype"
7373           From sizetype.U:
7374
7375           This variable defines sizetype to be something like size_t,
7376           unsigned long, or whatever type is used to declare length
7377           parameters for string functions.
7378
7379       "sleep"
7380           From Loc.U:
7381
7382           This variable is defined but not used by Configure.  The value is
7383           the empty string and is not useful.
7384
7385       "sLOCALTIME_max"
7386           From time_size.U:
7387
7388           This variable defines the maximum value of the time_t offset that
7389           the system function localtime () accepts
7390
7391       "sLOCALTIME_min"
7392           From time_size.U:
7393
7394           This variable defines the minimum value of the time_t offset that
7395           the system function localtime () accepts
7396
7397       "smail"
7398           From Loc.U:
7399
7400           This variable is defined but not used by Configure.  The value is
7401           the empty string and is not useful.
7402
7403       "so"
7404           From so.U:
7405
7406           This variable holds the extension used to identify shared libraries
7407           (also known as shared objects) on the system. Usually set to "so".
7408
7409       "sockethdr"
7410           From d_socket.U:
7411
7412           This variable has any cpp "-I" flags needed for socket support.
7413
7414       "socketlib"
7415           From d_socket.U:
7416
7417           This variable has the names of any libraries needed for socket
7418           support.
7419
7420       "socksizetype"
7421           From socksizetype.U:
7422
7423           This variable holds the type used for the size argument for various
7424           socket calls like accept.  Usual values include socklen_t, size_t,
7425           and int.
7426
7427       "sort"
7428           From Loc.U:
7429
7430           This variable is used internally by Configure to determine the full
7431           pathname (if any) of the sort program.  After Configure runs, the
7432           value is reset to a plain "sort" and is not useful.
7433
7434       "spackage"
7435           From package.U:
7436
7437           This variable contains the name of the package being constructed,
7438           with the first letter uppercased, i.e. suitable for starting
7439           sentences.
7440
7441       "spitshell"
7442           From spitshell.U:
7443
7444           This variable contains the command necessary to spit out a runnable
7445           shell on this system.  It is either cat or a grep "-v" for #
7446           comments.
7447
7448       "sPRId64"
7449           From quadfio.U:
7450
7451           This variable, if defined, contains the string used by stdio to
7452           format 64-bit decimal numbers (format "d") for output.
7453
7454       "sPRIeldbl"
7455           From longdblfio.U:
7456
7457           This variable, if defined, contains the string used by stdio to
7458           format long doubles (format "e") for output.
7459
7460       "sPRIEUldbl"
7461           From longdblfio.U:
7462
7463           This variable, if defined, contains the string used by stdio to
7464           format long doubles (format "E") for output.  The "U" in the name
7465           is to separate this from sPRIeldbl so that even case-blind systems
7466           can see the difference.
7467
7468       "sPRIfldbl"
7469           From longdblfio.U:
7470
7471           This variable, if defined, contains the string used by stdio to
7472           format long doubles (format "f") for output.
7473
7474       "sPRIFUldbl"
7475           From longdblfio.U:
7476
7477           This variable, if defined, contains the string used by stdio to
7478           format long doubles (format "F") for output.  The "U" in the name
7479           is to separate this from sPRIfldbl so that even case-blind systems
7480           can see the difference.
7481
7482       "sPRIgldbl"
7483           From longdblfio.U:
7484
7485           This variable, if defined, contains the string used by stdio to
7486           format long doubles (format "g") for output.
7487
7488       "sPRIGUldbl"
7489           From longdblfio.U:
7490
7491           This variable, if defined, contains the string used by stdio to
7492           format long doubles (format "G") for output.  The "U" in the name
7493           is to separate this from sPRIgldbl so that even case-blind systems
7494           can see the difference.
7495
7496       "sPRIi64"
7497           From quadfio.U:
7498
7499           This variable, if defined, contains the string used by stdio to
7500           format 64-bit decimal numbers (format "i") for output.
7501
7502       "sPRIo64"
7503           From quadfio.U:
7504
7505           This variable, if defined, contains the string used by stdio to
7506           format 64-bit octal numbers (format "o") for output.
7507
7508       "sPRIu64"
7509           From quadfio.U:
7510
7511           This variable, if defined, contains the string used by stdio to
7512           format 64-bit unsigned decimal numbers (format "u") for output.
7513
7514       "sPRIx64"
7515           From quadfio.U:
7516
7517           This variable, if defined, contains the string used by stdio to
7518           format 64-bit hexadecimal numbers (format "x") for output.
7519
7520       "sPRIXU64"
7521           From quadfio.U:
7522
7523           This variable, if defined, contains the string used by stdio to
7524           format 64-bit hExADECimAl numbers (format "X") for output.  The "U"
7525           in the name is to separate this from sPRIx64 so that even case-
7526           blind systems can see the difference.
7527
7528       "srand48_r_proto"
7529           From d_srand48_r.U:
7530
7531           This variable encodes the prototype of srand48_r.  It is zero if
7532           d_srand48_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
7533           of reentr.h if d_srand48_r is defined.
7534
7535       "srandom_r_proto"
7536           From d_srandom_r.U:
7537
7538           This variable encodes the prototype of srandom_r.  It is zero if
7539           d_srandom_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
7540           of reentr.h if d_srandom_r is defined.
7541
7542       "src"
7543           From src.U:
7544
7545           This variable holds the (possibly relative) path of the package
7546           source.  It is up to the Makefile to use this variable and set
7547           "VPATH" accordingly to find the sources remotely.  Use $pkgsrc to
7548           have an absolute path.
7549
7550       "sSCNfldbl"
7551           From longdblfio.U:
7552
7553           This variable, if defined, contains the string used by stdio to
7554           format long doubles (format "f") for input.
7555
7556       "ssizetype"
7557           From ssizetype.U:
7558
7559           This variable defines ssizetype to be something like ssize_t, long
7560           or int.  It is used by functions that return a count of bytes or an
7561           error condition.  It must be a signed type.  We will pick a type
7562           such that sizeof(SSize_t) == sizeof(Size_t).
7563
7564       "st_ino_sign"
7565           From st_ino_def.U:
7566
7567           This variable contains the signedness of struct stat's st_ino.  1
7568           for unsigned, -1 for signed.
7569
7570       "st_ino_size"
7571           From st_ino_def.U:
7572
7573           This variable contains the size of struct stat's st_ino in bytes.
7574
7575       "startperl"
7576           From startperl.U:
7577
7578           This variable contains the string to put on the front of a perl
7579           script to make sure (hopefully) that it runs with perl and not some
7580           shell. Of course, that leading line must be followed by the
7581           classical perl idiom: eval 'exec perl -S $0 ${1+$@}' if
7582           $running_under_some_shell; to guarantee perl startup should the
7583           shell execute the script. Note that this magic incantation is not
7584           understood by csh.
7585
7586       "startsh"
7587           From startsh.U:
7588
7589           This variable contains the string to put on the front of a shell
7590           script to make sure (hopefully) that it runs with sh and not some
7591           other shell.
7592
7593       "static_ext"
7594           From Extensions.U:
7595
7596           This variable holds a list of "XS" extension files we want to link
7597           statically into the package.  It is used by Makefile.
7598
7599       "stdchar"
7600           From stdchar.U:
7601
7602           This variable conditionally defines "STDCHAR" to be the type of
7603           char used in stdio.h.  It has the values "unsigned char" or "char".
7604
7605       "stdio_base"
7606           From d_stdstdio.U:
7607
7608           This variable defines how, given a "FILE" pointer, fp, to access
7609           the _base field (or equivalent) of stdio.h's "FILE" structure.
7610           This will be used to define the macro FILE_base(fp).
7611
7612       "stdio_bufsiz"
7613           From d_stdstdio.U:
7614
7615           This variable defines how, given a "FILE" pointer, fp, to determine
7616           the number of bytes store in the I/O buffer pointer to by the _base
7617           field (or equivalent) of stdio.h's "FILE" structure.  This will be
7618           used to define the macro FILE_bufsiz(fp).
7619
7620       "stdio_cnt"
7621           From d_stdstdio.U:
7622
7623           This variable defines how, given a "FILE" pointer, fp, to access
7624           the _cnt field (or equivalent) of stdio.h's "FILE" structure.  This
7625           will be used to define the macro FILE_cnt(fp).
7626
7627       "stdio_filbuf"
7628           From d_stdstdio.U:
7629
7630           This variable defines how, given a "FILE" pointer, fp, to tell
7631           stdio to refill its internal buffers (?).  This will be used to
7632           define the macro FILE_filbuf(fp).
7633
7634       "stdio_ptr"
7635           From d_stdstdio.U:
7636
7637           This variable defines how, given a "FILE" pointer, fp, to access
7638           the _ptr field (or equivalent) of stdio.h's "FILE" structure.  This
7639           will be used to define the macro FILE_ptr(fp).
7640
7641       "stdio_stream_array"
7642           From stdio_streams.U:
7643
7644           This variable tells the name of the array holding the stdio
7645           streams.  Usual values include _iob, __iob, and __sF.
7646
7647       "strerror_r_proto"
7648           From d_strerror_r.U:
7649
7650           This variable encodes the prototype of strerror_r.  It is zero if
7651           d_strerror_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
7652           macros of reentr.h if d_strerror_r is defined.
7653
7654       "submit"
7655           From Loc.U:
7656
7657           This variable is defined but not used by Configure.  The value is
7658           the empty string and is not useful.
7659
7660       "subversion"
7661           From patchlevel.U:
7662
7663           The subversion level of this package.  The value of subversion
7664           comes from the patchlevel.h file.  In a version number such as
7665           5.6.1, this is the 1.  In patchlevel.h, this is referred to as
7666           "PERL_SUBVERSION".  This is unique to perl.
7667
7668       "sysman"
7669           From sysman.U:
7670
7671           This variable holds the place where the manual is located on this
7672           system. It is not the place where the user wants to put his manual
7673           pages. Rather it is the place where Configure may look to find
7674           manual for unix commands (section 1 of the manual usually). See
7675           mansrc.
7676
7677       "sysroot"
7678           From Sysroot.U:
7679
7680           This variable is empty unless supplied by the Configure user.  It
7681           can contain a path to an alternative root directory, under which
7682           headers and libraries for the compilation target can be found. This
7683           is generally used when cross-compiling using a gcc-like compiler.
7684
7685   t
7686       "tail"
7687           From Loc.U:
7688
7689           This variable is defined but not used by Configure.  The value is
7690           the empty string and is not useful.
7691
7692       "tar"
7693           From Loc.U:
7694
7695           This variable is defined but not used by Configure.  The value is
7696           the empty string and is not useful.
7697
7698       "targetarch"
7699           From Cross.U:
7700
7701           If cross-compiling, this variable contains the target architecture.
7702           If not, this will be empty.
7703
7704       "targetdir"
7705           From Cross.U:
7706
7707           This variable contains a path that will be created on the target
7708           host using targetmkdir, and then used to copy the cross-compiled
7709           executables to. Defaults to /tmp if not set.
7710
7711       "targetenv"
7712           From Cross.U:
7713
7714           If cross-compiling, this variable can be used to modify the
7715           environment on the target system.  However, how and where it's
7716           used, and even if it's used at all, is entirely dependent on both
7717           the transport mechanism (targetrun) and what the target system is.
7718           Unless the relevant documentation says otherwise, it is genereally
7719           not useful.
7720
7721       "targethost"
7722           From Cross.U:
7723
7724           This variable contains the name of a separate host machine that can
7725           be used to run compiled test programs and perl tests on.  Set to
7726           empty string if not in use.
7727
7728       "targetmkdir"
7729           From Cross.U:
7730
7731           This variable contains the command used by Configure to create a
7732           new directory on the target host.
7733
7734       "targetport"
7735           From Cross.U:
7736
7737           This variable contains the number of a network port to be used to
7738           connect to the host in targethost, if unset defaults to 22 for ssh.
7739
7740       "targetsh"
7741           From sh.U:
7742
7743           If cross-compiling, this variable contains the location of sh on
7744           the target system.  If not, this will be the same as $sh.
7745
7746       "tbl"
7747           From Loc.U:
7748
7749           This variable is defined but not used by Configure.  The value is
7750           the empty string and is not useful.
7751
7752       "tee"
7753           From Loc.U:
7754
7755           This variable is defined but not used by Configure.  The value is
7756           the empty string and is not useful.
7757
7758       "test"
7759           From Loc.U:
7760
7761           This variable is used internally by Configure to determine the full
7762           pathname (if any) of the test program.  After Configure runs, the
7763           value is reset to a plain "test" and is not useful.
7764
7765       "timeincl"
7766           From i_time.U:
7767
7768           This variable holds the full path of the included time header(s).
7769
7770       "timetype"
7771           From d_time.U:
7772
7773           This variable holds the type returned by time(). It can be long, or
7774           time_t on "BSD" sites (in which case <sys/types.h> should be
7775           included). Anyway, the type Time_t should be used.
7776
7777       "tmpnam_r_proto"
7778           From d_tmpnam_r.U:
7779
7780           This variable encodes the prototype of tmpnam_r.  It is zero if
7781           d_tmpnam_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
7782           of reentr.h if d_tmpnam_r is defined.
7783
7784       "to"
7785           From Cross.U:
7786
7787           This variable contains the command used by Configure to copy to
7788           from the target host.  Useful and available only during Perl build.
7789           The string ":" if not cross-compiling.
7790
7791       "touch"
7792           From Loc.U:
7793
7794           This variable is used internally by Configure to determine the full
7795           pathname (if any) of the touch program.  After Configure runs, the
7796           value is reset to a plain "touch" and is not useful.
7797
7798       "tr"
7799           From Loc.U:
7800
7801           This variable is used internally by Configure to determine the full
7802           pathname (if any) of the tr program.  After Configure runs, the
7803           value is reset to a plain "tr" and is not useful.
7804
7805       "trnl"
7806           From trnl.U:
7807
7808           This variable contains the value to be passed to the tr(1) command
7809           to transliterate a newline.  Typical values are "\012" and "\n".
7810           This is needed for "EBCDIC" systems where newline is not
7811           necessarily "\012".
7812
7813       "troff"
7814           From Loc.U:
7815
7816           This variable is defined but not used by Configure.  The value is
7817           the empty string and is not useful.
7818
7819       "ttyname_r_proto"
7820           From d_ttyname_r.U:
7821
7822           This variable encodes the prototype of ttyname_r.  It is zero if
7823           d_ttyname_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
7824           of reentr.h if d_ttyname_r is defined.
7825
7826   u
7827       "u16size"
7828           From perlxv.U:
7829
7830           This variable is the size of an U16 in bytes.
7831
7832       "u16type"
7833           From perlxv.U:
7834
7835           This variable contains the C type used for Perl's U16.
7836
7837       "u32size"
7838           From perlxv.U:
7839
7840           This variable is the size of an U32 in bytes.
7841
7842       "u32type"
7843           From perlxv.U:
7844
7845           This variable contains the C type used for Perl's U32.
7846
7847       "u64size"
7848           From perlxv.U:
7849
7850           This variable is the size of an U64 in bytes.
7851
7852       "u64type"
7853           From perlxv.U:
7854
7855           This variable contains the C type used for Perl's U64.
7856
7857       "u8size"
7858           From perlxv.U:
7859
7860           This variable is the size of an U8 in bytes.
7861
7862       "u8type"
7863           From perlxv.U:
7864
7865           This variable contains the C type used for Perl's U8.
7866
7867       "uidformat"
7868           From uidf.U:
7869
7870           This variable contains the format string used for printing a Uid_t.
7871
7872       "uidsign"
7873           From uidsign.U:
7874
7875           This variable contains the signedness of a uidtype.  1 for
7876           unsigned, -1 for signed.
7877
7878       "uidsize"
7879           From uidsize.U:
7880
7881           This variable contains the size of a uidtype in bytes.
7882
7883       "uidtype"
7884           From uidtype.U:
7885
7886           This variable defines Uid_t to be something like uid_t, int,
7887           ushort, or whatever type is used to declare user ids in the kernel.
7888
7889       "uname"
7890           From Loc.U:
7891
7892           This variable is used internally by Configure to determine the full
7893           pathname (if any) of the uname program.  After Configure runs, the
7894           value is reset to a plain "uname" and is not useful.
7895
7896       "uniq"
7897           From Loc.U:
7898
7899           This variable is used internally by Configure to determine the full
7900           pathname (if any) of the uniq program.  After Configure runs, the
7901           value is reset to a plain "uniq" and is not useful.
7902
7903       "uquadtype"
7904           From quadtype.U:
7905
7906           This variable defines Uquad_t to be something like unsigned long,
7907           unsigned int, unsigned long long, uint64_t, or whatever type is
7908           used for 64-bit integers.
7909
7910       "use5005threads"
7911           From usethreads.U:
7912
7913           This variable conditionally defines the USE_5005THREADS symbol, and
7914           indicates that Perl should be built to use the 5.005-based
7915           threading implementation. Only valid up to 5.8.x.
7916
7917       "use64bitall"
7918           From use64bits.U:
7919
7920           This variable conditionally defines the USE_64_BIT_ALL symbol, and
7921           indicates that 64-bit integer types should be used when available.
7922           The maximal possible 64-bitness is employed: LP64 or ILP64, meaning
7923           that you will be able to use more than 2 gigabytes of memory.  This
7924           mode is even more binary incompatible than USE_64_BIT_INT. You may
7925           not be able to run the resulting executable in a 32-bit "CPU" at
7926           all or you may need at least to reboot your "OS" to 64-bit mode.
7927
7928       "use64bitint"
7929           From use64bits.U:
7930
7931           This variable conditionally defines the USE_64_BIT_INT symbol, and
7932           indicates that 64-bit integer types should be used when available.
7933           The minimal possible 64-bitness is employed, just enough to get
7934           64-bit integers into Perl.  This may mean using for example "long
7935           longs", while your memory may still be limited to 2 gigabytes.
7936
7937       "usecbacktrace"
7938           From usebacktrace.U:
7939
7940           This variable indicates whether we are compiling with backtrace
7941           support.
7942
7943       "usecrosscompile"
7944           From Cross.U:
7945
7946           This variable conditionally defines the "USE_CROSS_COMPILE" symbol,
7947           and indicates that Perl has been cross-compiled.
7948
7949       "usedevel"
7950           From Devel.U:
7951
7952           This variable indicates that Perl was configured with development
7953           features enabled.  This should not be done for production builds.
7954
7955       "usedl"
7956           From dlsrc.U:
7957
7958           This variable indicates if the system supports dynamic loading of
7959           some sort.  See also dlsrc and dlobj.
7960
7961       "usedtrace"
7962           From usedtrace.U:
7963
7964           This variable indicates whether we are compiling with dtrace
7965           support. See also dtrace.
7966
7967       "usefaststdio"
7968           From usefaststdio.U:
7969
7970           This variable conditionally defines the "USE_FAST_STDIO" symbol,
7971           and indicates that Perl should be built to use "fast stdio".
7972           Defaults to define in Perls 5.8 and earlier, to undef later.
7973
7974       "useithreads"
7975           From usethreads.U:
7976
7977           This variable conditionally defines the "USE_ITHREADS" symbol, and
7978           indicates that Perl should be built to use the interpreter-based
7979           threading implementation.
7980
7981       "usekernprocpathname"
7982           From usekernprocpathname.U:
7983
7984           This variable, indicates that we can use sysctl with
7985           "KERN_PROC_PATHNAME" to get a full path for the executable, and
7986           hence convert $^X to an absolute path.
7987
7988       "uselanginfo"
7989           From Extensions.U:
7990
7991           This variable holds either "true" or "false" to indicate whether
7992           the I18N::Langinfo extension should be used.  The sole use for this
7993           currently is to allow an easy mechanism for users to skip this
7994           extension from the Configure command line.
7995
7996       "uselargefiles"
7997           From uselfs.U:
7998
7999           This variable conditionally defines the "USE_LARGE_FILES" symbol,
8000           and indicates that large file interfaces should be used when
8001           available.
8002
8003       "uselongdouble"
8004           From uselongdbl.U:
8005
8006           This variable conditionally defines the "USE_LONG_DOUBLE" symbol,
8007           and indicates that long doubles should be used when available.
8008
8009       "usemallocwrap"
8010           From mallocsrc.U:
8011
8012           This variable contains y if we are wrapping malloc to prevent
8013           integer overflow during size calculations.
8014
8015       "usemorebits"
8016           From usemorebits.U:
8017
8018           This variable conditionally defines the "USE_MORE_BITS" symbol, and
8019           indicates that explicit 64-bit interfaces and long doubles should
8020           be used when available.
8021
8022       "usemultiplicity"
8023           From usemultiplicity.U:
8024
8025           This variable conditionally defines the "MULTIPLICITY" symbol, and
8026           indicates that Perl should be built to use multiplicity.
8027
8028       "usemymalloc"
8029           From mallocsrc.U:
8030
8031           This variable contains y if the malloc that comes with this package
8032           is desired over the system's version of malloc.  People often
8033           include special versions of malloc for efficiency, but such
8034           versions are often less portable.  See also mallocsrc and
8035           mallocobj.  If this is "y", then -lmalloc is removed from $libs.
8036
8037       "usenm"
8038           From usenm.U:
8039
8040           This variable contains "true" or "false" depending whether the nm
8041           extraction is wanted or not.
8042
8043       "usensgetexecutablepath"
8044           From usensgetexecutablepath.U:
8045
8046           This symbol, if defined, indicates that we can use
8047           _NSGetExecutablePath and realpath to get a full path for the
8048           executable, and hence convert $^X to an absolute path.
8049
8050       "useopcode"
8051           From Extensions.U:
8052
8053           This variable holds either "true" or "false" to indicate whether
8054           the Opcode extension should be used.  The sole use for this
8055           currently is to allow an easy mechanism for users to skip the
8056           Opcode extension from the Configure command line.
8057
8058       "useperlio"
8059           From useperlio.U:
8060
8061           This variable conditionally defines the "USE_PERLIO" symbol, and
8062           indicates that the PerlIO abstraction should be used throughout.
8063
8064       "useposix"
8065           From Extensions.U:
8066
8067           This variable holds either "true" or "false" to indicate whether
8068           the "POSIX" extension should be used.  The sole use for this
8069           currently is to allow an easy mechanism for hints files to indicate
8070           that "POSIX" will not compile on a particular system.
8071
8072       "usequadmath"
8073           From usequadmath.U:
8074
8075           This variable conditionally defines the "USE_QUADMATH" symbol, and
8076           indicates that the quadmath library __float128 long doubles should
8077           be used when available.
8078
8079       "usereentrant"
8080           From usethreads.U:
8081
8082           This variable conditionally defines the "USE_REENTRANT_API" symbol,
8083           which indicates that the thread code may try to use the various _r
8084           versions of library functions.  This is only potentially meaningful
8085           if usethreads is set and is very experimental, it is not even
8086           prompted for.
8087
8088       "userelocatableinc"
8089           From bin.U:
8090
8091           This variable is set to true to indicate that perl should relocate
8092           @"INC" entries at runtime based on the path to the perl binary.
8093           Any @"INC" paths starting .../ are relocated relative to the
8094           directory containing the perl binary, and a logical cleanup of the
8095           path is then made around the join point (removing dir/../ pairs)
8096
8097       "useshrplib"
8098           From libperl.U:
8099
8100           This variable is set to "true" if the user wishes to build a shared
8101           libperl, and "false" otherwise.
8102
8103       "usesitecustomize"
8104           From d_sitecustomize.U:
8105
8106           This variable is set to true when the user requires a mechanism
8107           that allows the sysadmin to add entries to @"INC" at runtime.  This
8108           variable being set, makes perl run $sitelib/sitecustomize.pl at
8109           startup.
8110
8111       "usesocks"
8112           From usesocks.U:
8113
8114           This variable conditionally defines the "USE_SOCKS" symbol, and
8115           indicates that Perl should be built to use "SOCKS".
8116
8117       "usethreads"
8118           From usethreads.U:
8119
8120           This variable conditionally defines the "USE_THREADS" symbol, and
8121           indicates that Perl should be built to use threads.
8122
8123       "usevendorprefix"
8124           From vendorprefix.U:
8125
8126           This variable tells whether the vendorprefix and consequently other
8127           vendor* paths are in use.
8128
8129       "useversionedarchname"
8130           From archname.U:
8131
8132           This variable indicates whether to include the $api_versionstring
8133           as a component of the $archname.
8134
8135       "usevfork"
8136           From d_vfork.U:
8137
8138           This variable is set to true when the user accepts to use vfork.
8139           It is set to false when no vfork is available or when the user
8140           explicitly requests not to use vfork.
8141
8142       "usrinc"
8143           From usrinc.U:
8144
8145           This variable holds the path of the include files, which is usually
8146           /usr/include. It is mainly used by other Configure units.
8147
8148       "uuname"
8149           From Loc.U:
8150
8151           This variable is defined but not used by Configure.  The value is
8152           the empty string and is not useful.
8153
8154       "uvoformat"
8155           From perlxvf.U:
8156
8157           This variable contains the format string used for printing a Perl
8158           "UV" as an unsigned octal integer.
8159
8160       "uvsize"
8161           From perlxv.U:
8162
8163           This variable is the size of a "UV" in bytes.
8164
8165       "uvtype"
8166           From perlxv.U:
8167
8168           This variable contains the C type used for Perl's "UV".
8169
8170       "uvuformat"
8171           From perlxvf.U:
8172
8173           This variable contains the format string used for printing a Perl
8174           "UV" as an unsigned decimal integer.
8175
8176       "uvxformat"
8177           From perlxvf.U:
8178
8179           This variable contains the format string used for printing a Perl
8180           "UV" as an unsigned hexadecimal integer in lowercase abcdef.
8181
8182       "uvXUformat"
8183           From perlxvf.U:
8184
8185           This variable contains the format string used for printing a Perl
8186           "UV" as an unsigned hexadecimal integer in uppercase "ABCDEF".
8187
8188   v
8189       "vendorarch"
8190           From vendorarch.U:
8191
8192           This variable contains the value of the "PERL_VENDORARCH" symbol.
8193           It may have a ~ on the front.  The standard distribution will put
8194           nothing in this directory.  Vendors who distribute perl may wish to
8195           place their own architecture-dependent modules and extensions in
8196           this directory with MakeMaker Makefile.PL "INSTALLDIRS"=vendor or
8197           equivalent.  See "INSTALL" for details.
8198
8199       "vendorarchexp"
8200           From vendorarch.U:
8201
8202           This variable is the ~name expanded version of vendorarch, so that
8203           you may use it directly in Makefiles or shell scripts.
8204
8205       "vendorbin"
8206           From vendorbin.U:
8207
8208           This variable contains the eventual value of the "VENDORBIN"
8209           symbol.  It may have a ~ on the front.  The standard distribution
8210           will put nothing in this directory.  Vendors who distribute perl
8211           may wish to place additional binaries in this directory with
8212           MakeMaker Makefile.PL "INSTALLDIRS"=vendor or equivalent.  See
8213           "INSTALL" for details.
8214
8215       "vendorbinexp"
8216           From vendorbin.U:
8217
8218           This variable is the ~name expanded version of vendorbin, so that
8219           you may use it directly in Makefiles or shell scripts.
8220
8221       "vendorhtml1dir"
8222           From vendorhtml1dir.U:
8223
8224           This variable contains the name of the directory for html pages.
8225           It may have a ~ on the front.  The standard distribution will put
8226           nothing in this directory.  Vendors who distribute perl may wish to
8227           place their own html pages in this directory with MakeMaker
8228           Makefile.PL "INSTALLDIRS"=vendor or equivalent.  See "INSTALL" for
8229           details.
8230
8231       "vendorhtml1direxp"
8232           From vendorhtml1dir.U:
8233
8234           This variable is the ~name expanded version of vendorhtml1dir, so
8235           that you may use it directly in Makefiles or shell scripts.
8236
8237       "vendorhtml3dir"
8238           From vendorhtml3dir.U:
8239
8240           This variable contains the name of the directory for html library
8241           pages.  It may have a ~ on the front.  The standard distribution
8242           will put nothing in this directory.  Vendors who distribute perl
8243           may wish to place their own html pages for modules and extensions
8244           in this directory with MakeMaker Makefile.PL "INSTALLDIRS"=vendor
8245           or equivalent.  See "INSTALL" for details.
8246
8247       "vendorhtml3direxp"
8248           From vendorhtml3dir.U:
8249
8250           This variable is the ~name expanded version of vendorhtml3dir, so
8251           that you may use it directly in Makefiles or shell scripts.
8252
8253       "vendorlib"
8254           From vendorlib.U:
8255
8256           This variable contains the eventual value of the "VENDORLIB"
8257           symbol, which is the name of the private library for this package.
8258           The standard distribution will put nothing in this directory.
8259           Vendors who distribute perl may wish to place their own modules in
8260           this directory with MakeMaker Makefile.PL "INSTALLDIRS"=vendor or
8261           equivalent.  See "INSTALL" for details.
8262
8263       "vendorlib_stem"
8264           From vendorlib.U:
8265
8266           This variable is $vendorlibexp with any trailing version-specific
8267           component removed.  The elements in inc_version_list
8268           (inc_version_list.U) can be tacked onto this variable to generate a
8269           list of directories to search.
8270
8271       "vendorlibexp"
8272           From vendorlib.U:
8273
8274           This variable is the ~name expanded version of vendorlib, so that
8275           you may use it directly in Makefiles or shell scripts.
8276
8277       "vendorman1dir"
8278           From vendorman1dir.U:
8279
8280           This variable contains the name of the directory for man1 pages.
8281           It may have a ~ on the front.  The standard distribution will put
8282           nothing in this directory.  Vendors who distribute perl may wish to
8283           place their own man1 pages in this directory with MakeMaker
8284           Makefile.PL "INSTALLDIRS"=vendor or equivalent.  See "INSTALL" for
8285           details.
8286
8287       "vendorman1direxp"
8288           From vendorman1dir.U:
8289
8290           This variable is the ~name expanded version of vendorman1dir, so
8291           that you may use it directly in Makefiles or shell scripts.
8292
8293       "vendorman3dir"
8294           From vendorman3dir.U:
8295
8296           This variable contains the name of the directory for man3 pages.
8297           It may have a ~ on the front.  The standard distribution will put
8298           nothing in this directory.  Vendors who distribute perl may wish to
8299           place their own man3 pages in this directory with MakeMaker
8300           Makefile.PL "INSTALLDIRS"=vendor or equivalent.  See "INSTALL" for
8301           details.
8302
8303       "vendorman3direxp"
8304           From vendorman3dir.U:
8305
8306           This variable is the ~name expanded version of vendorman3dir, so
8307           that you may use it directly in Makefiles or shell scripts.
8308
8309       "vendorprefix"
8310           From vendorprefix.U:
8311
8312           This variable holds the full absolute path of the directory below
8313           which the vendor will install add-on packages.  See "INSTALL" for
8314           usage and examples.
8315
8316       "vendorprefixexp"
8317           From vendorprefix.U:
8318
8319           This variable holds the full absolute path of the directory below
8320           which the vendor will install add-on packages.  Derived from
8321           vendorprefix.
8322
8323       "vendorscript"
8324           From vendorscript.U:
8325
8326           This variable contains the eventual value of the "VENDORSCRIPT"
8327           symbol.  It may have a ~ on the front.  The standard distribution
8328           will put nothing in this directory.  Vendors who distribute perl
8329           may wish to place additional executable scripts in this directory
8330           with MakeMaker Makefile.PL "INSTALLDIRS"=vendor or equivalent.  See
8331           "INSTALL" for details.
8332
8333       "vendorscriptexp"
8334           From vendorscript.U:
8335
8336           This variable is the ~name expanded version of vendorscript, so
8337           that you may use it directly in Makefiles or shell scripts.
8338
8339       "version"
8340           From patchlevel.U:
8341
8342           The full version number of this package, such as 5.6.1 (or 5_6_1).
8343           This combines revision, patchlevel, and subversion to get the full
8344           version number, including any possible subversions.  This is
8345           suitable for use as a directory name, and hence is filesystem
8346           dependent.
8347
8348       "version_patchlevel_string"
8349           From patchlevel.U:
8350
8351           This is a string combining version, subversion and perl_patchlevel
8352           (if perl_patchlevel is non-zero).  It is typically something like
8353           'version 7 subversion 1'  or 'version 7 subversion 1 patchlevel
8354           11224' It is computed here to avoid duplication of code in
8355           myconfig.SH and lib/Config.pm.
8356
8357       "versiononly"
8358           From versiononly.U:
8359
8360           If set, this symbol indicates that only the version-specific
8361           components of a perl installation should be installed.  This may be
8362           useful for making a test installation of a new version without
8363           disturbing the existing installation.  Setting versiononly is
8364           equivalent to setting installperl's -v option.  In particular, the
8365           non-versioned scripts and programs such as a2p, c2ph, h2xs, pod2*,
8366           and perldoc are not installed (see "INSTALL" for a more complete
8367           list).  Nor are the man pages installed.  Usually, this is undef.
8368
8369       "vi"
8370           From Loc.U:
8371
8372           This variable is defined but not used by Configure.  The value is
8373           the empty string and is not useful.
8374
8375   x
8376       "xlibpth"
8377           From libpth.U:
8378
8379           This variable holds extra path (space-separated) used to find
8380           libraries on this platform, for example "CPU"-specific libraries
8381           (on multi-"CPU" platforms) may be listed here.
8382
8383   y
8384       "yacc"
8385           From yacc.U:
8386
8387           This variable holds the name of the compiler compiler we want to
8388           use in the Makefile. It can be yacc, byacc, or bison -y.
8389
8390       "yaccflags"
8391           From yacc.U:
8392
8393           This variable contains any additional yacc flags desired by the
8394           user.  It is up to the Makefile to use this.
8395
8396   z
8397       "zcat"
8398           From Loc.U:
8399
8400           This variable is defined but not used by Configure.  The value is
8401           the empty string and is not useful.
8402
8403       "zip"
8404           From Loc.U:
8405
8406           This variable is used internally by Configure to determine the full
8407           pathname (if any) of the zip program.  After Configure runs, the
8408           value is reset to a plain "zip" and is not useful.
8409

GIT DATA

8411       Information on the git commit from which the current perl binary was
8412       compiled can be found in the variable $Config::Git_Data.  The variable
8413       is a structured string that looks something like this:
8414
8415         git_commit_id='ea0c2dbd5f5ac6845ecc7ec6696415bf8e27bd52'
8416         git_describe='GitLive-blead-1076-gea0c2db'
8417         git_branch='smartmatch'
8418         git_uncommitted_changes=''
8419         git_commit_id_title='Commit id:'
8420         git_commit_date='2009-05-09 17:47:31 +0200'
8421
8422       Its format is not guaranteed not to change over time.
8423

NOTE

8425       This module contains a good example of how to use tie to implement a
8426       cache and an example of how to make a tied variable readonly to those
8427       outside of it.
8428
8429
8430
8431perl v5.30.1                      2019-11-29                       Config(3pm)
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