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 pattern matching (usually on "BSD"). If so, it is
3139           likely 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 pattern matching (usually 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 pattern matching (usually on POSIX.2 conforming
3193           systems).
3194
3195       "d_remainder"
3196           From d_remainder.U:
3197
3198           This variable conditionally defines the "HAS_REMAINDER" symbol,
3199           which indicates to the C program that the remainder() routine is
3200           available.
3201
3202       "d_remquo"
3203           From d_remquo.U:
3204
3205           This variable conditionally defines the "HAS_REMQUO" symbol, which
3206           indicates to the C program that the remquo() routine is available.
3207
3208       "d_rename"
3209           From d_rename.U:
3210
3211           This variable conditionally defines the "HAS_RENAME" symbol, which
3212           indicates to the C program that the rename() routine is available
3213           to rename files.
3214
3215       "d_renameat"
3216           From d_fsat.U:
3217
3218           This variable conditionally defines the "HAS_RENAMEAT" symbol,
3219           which indicates the "POSIX" renameat() function is available.
3220
3221       "d_rewinddir"
3222           From d_readdir.U:
3223
3224           This variable conditionally defines "HAS_REWINDDIR" if rewinddir()
3225           is available.
3226
3227       "d_rint"
3228           From d_rint.U:
3229
3230           This variable conditionally defines the "HAS_RINT" symbol, which
3231           indicates to the C program that the rint() routine is available.
3232
3233       "d_rmdir"
3234           From d_rmdir.U:
3235
3236           This variable conditionally defines "HAS_RMDIR" if rmdir() is
3237           available to remove directories.
3238
3239       "d_round"
3240           From d_round.U:
3241
3242           This variable conditionally defines the "HAS_ROUND" symbol, which
3243           indicates to the C program that the round() routine is available.
3244
3245       "d_sbrkproto"
3246           From d_sbrkproto.U:
3247
3248           This variable conditionally defines the "HAS_SBRK_PROTO" symbol,
3249           which indicates to the C program that the system provides a
3250           prototype for the sbrk() function.  Otherwise, it is up to the
3251           program to supply one.
3252
3253       "d_scalbn"
3254           From d_scalbn.U:
3255
3256           This variable conditionally defines the "HAS_SCALBN" symbol, which
3257           indicates to the C program that the scalbn() routine is available.
3258
3259       "d_scalbnl"
3260           From d_scalbnl.U:
3261
3262           This variable conditionally defines the "HAS_SCALBNL" symbol, which
3263           indicates to the C program that the scalbnl() routine is available.
3264           If ilogbl is also present we can emulate frexpl.
3265
3266       "d_sched_yield"
3267           From d_pthread_y.U:
3268
3269           This variable conditionally defines the "HAS_SCHED_YIELD" symbol if
3270           the sched_yield routine is available to yield the execution of the
3271           current thread.
3272
3273       "d_scm_rights"
3274           From d_socket.U:
3275
3276           This variable conditionally defines the "HAS_SCM_RIGHTS" symbol,
3277           which indicates that the "SCM_RIGHTS" is available.  #ifdef is not
3278           enough because it may be an enum, glibc has been known to do this.
3279
3280       "d_SCNfldbl"
3281           From longdblfio.U:
3282
3283           This variable conditionally defines the PERL_PRIfldbl symbol, which
3284           indicates that stdio has a symbol to scan long doubles.
3285
3286       "d_seekdir"
3287           From d_readdir.U:
3288
3289           This variable conditionally defines "HAS_SEEKDIR" if seekdir() is
3290           available.
3291
3292       "d_select"
3293           From d_select.U:
3294
3295           This variable conditionally defines "HAS_SELECT" if select() is
3296           available to select active file descriptors. A <sys/time.h>
3297           inclusion may be necessary for the timeout field.
3298
3299       "d_sem"
3300           From d_sem.U:
3301
3302           This variable conditionally defines the "HAS_SEM" symbol, which
3303           indicates that the entire sem*(2) library is present.
3304
3305       "d_semctl"
3306           From d_semctl.U:
3307
3308           This variable conditionally defines the "HAS_SEMCTL" symbol, which
3309           indicates to the C program that the semctl() routine is available.
3310
3311       "d_semctl_semid_ds"
3312           From d_union_semun.U:
3313
3314           This variable conditionally defines "USE_SEMCTL_SEMID_DS", which
3315           indicates that struct semid_ds * is to be used for semctl
3316           "IPC_STAT".
3317
3318       "d_semctl_semun"
3319           From d_union_semun.U:
3320
3321           This variable conditionally defines "USE_SEMCTL_SEMUN", which
3322           indicates that union semun is to be used for semctl "IPC_STAT".
3323
3324       "d_semget"
3325           From d_semget.U:
3326
3327           This variable conditionally defines the "HAS_SEMGET" symbol, which
3328           indicates to the C program that the semget() routine is available.
3329
3330       "d_semop"
3331           From d_semop.U:
3332
3333           This variable conditionally defines the "HAS_SEMOP" symbol, which
3334           indicates to the C program that the semop() routine is available.
3335
3336       "d_sendmsg"
3337           From d_sendmsg.U:
3338
3339           This variable conditionally defines the "HAS_SENDMSG" symbol, which
3340           indicates to the C program that the sendmsg() routine is available.
3341
3342       "d_setegid"
3343           From d_setegid.U:
3344
3345           This variable conditionally defines the "HAS_SETEGID" symbol, which
3346           indicates to the C program that the setegid() routine is available
3347           to change the effective gid of the current program.
3348
3349       "d_seteuid"
3350           From d_seteuid.U:
3351
3352           This variable conditionally defines the "HAS_SETEUID" symbol, which
3353           indicates to the C program that the seteuid() routine is available
3354           to change the effective uid of the current program.
3355
3356       "d_setgrent"
3357           From d_setgrent.U:
3358
3359           This variable conditionally defines the "HAS_SETGRENT" symbol,
3360           which indicates to the C program that the setgrent() routine is
3361           available for initializing sequential access to the group database.
3362
3363       "d_setgrent_r"
3364           From d_setgrent_r.U:
3365
3366           This variable conditionally defines the "HAS_SETGRENT_R" symbol,
3367           which indicates to the C program that the setgrent_r() routine is
3368           available.
3369
3370       "d_setgrps"
3371           From d_setgrps.U:
3372
3373           This variable conditionally defines the "HAS_SETGROUPS" symbol,
3374           which indicates to the C program that the setgroups() routine is
3375           available to set the list of process groups.
3376
3377       "d_sethent"
3378           From d_sethent.U:
3379
3380           This variable conditionally defines "HAS_SETHOSTENT" if
3381           sethostent() is available.
3382
3383       "d_sethostent_r"
3384           From d_sethostent_r.U:
3385
3386           This variable conditionally defines the "HAS_SETHOSTENT_R" symbol,
3387           which indicates to the C program that the sethostent_r() routine is
3388           available.
3389
3390       "d_setitimer"
3391           From d_setitimer.U:
3392
3393           This variable conditionally defines the "HAS_SETITIMER" symbol,
3394           which indicates to the C program that the setitimer() routine is
3395           available.
3396
3397       "d_setlinebuf"
3398           From d_setlnbuf.U:
3399
3400           This variable conditionally defines the "HAS_SETLINEBUF" symbol,
3401           which indicates to the C program that the setlinebuf() routine is
3402           available to change stderr or stdout from block-buffered or
3403           unbuffered to a line-buffered mode.
3404
3405       "d_setlocale"
3406           From d_setlocale.U:
3407
3408           This variable conditionally defines "HAS_SETLOCALE" if setlocale()
3409           is available to handle locale-specific ctype implementations.
3410
3411       "d_setlocale_accepts_any_locale_name"
3412           From d_setlocale.U:
3413
3414           This variable conditionally defines
3415           "SETLOCALE_ACCEPTS_ANY_LOCALE_NAME" if setlocale() accepts any
3416           locale name.
3417
3418       "d_setlocale_r"
3419           From d_setlocale_r.U:
3420
3421           This variable conditionally defines the "HAS_SETLOCALE_R" symbol,
3422           which indicates to the C program that the setlocale_r() routine is
3423           available.
3424
3425       "d_setnent"
3426           From d_setnent.U:
3427
3428           This variable conditionally defines "HAS_SETNETENT" if setnetent()
3429           is available.
3430
3431       "d_setnetent_r"
3432           From d_setnetent_r.U:
3433
3434           This variable conditionally defines the "HAS_SETNETENT_R" symbol,
3435           which indicates to the C program that the setnetent_r() routine is
3436           available.
3437
3438       "d_setpent"
3439           From d_setpent.U:
3440
3441           This variable conditionally defines "HAS_SETPROTOENT" if
3442           setprotoent() is available.
3443
3444       "d_setpgid"
3445           From d_setpgid.U:
3446
3447           This variable conditionally defines the "HAS_SETPGID" symbol if the
3448           setpgid(pid, gpid) function is available to set process group "ID".
3449
3450       "d_setpgrp"
3451           From d_setpgrp.U:
3452
3453           This variable conditionally defines "HAS_SETPGRP" if setpgrp() is
3454           available to set the current process group.
3455
3456       "d_setpgrp2"
3457           From d_setpgrp2.U:
3458
3459           This variable conditionally defines the HAS_SETPGRP2 symbol, which
3460           indicates to the C program that the setpgrp2() (as in DG/"UX")
3461           routine is available to set the current process group.
3462
3463       "d_setprior"
3464           From d_setprior.U:
3465
3466           This variable conditionally defines "HAS_SETPRIORITY" if
3467           setpriority() is available to set a process's priority.
3468
3469       "d_setproctitle"
3470           From d_setproctitle.U:
3471
3472           This variable conditionally defines the "HAS_SETPROCTITLE" symbol,
3473           which indicates to the C program that the setproctitle() routine is
3474           available.
3475
3476       "d_setprotoent_r"
3477           From d_setprotoent_r.U:
3478
3479           This variable conditionally defines the "HAS_SETPROTOENT_R" symbol,
3480           which indicates to the C program that the setprotoent_r() routine
3481           is available.
3482
3483       "d_setpwent"
3484           From d_setpwent.U:
3485
3486           This variable conditionally defines the "HAS_SETPWENT" symbol,
3487           which indicates to the C program that the setpwent() routine is
3488           available for initializing sequential access to the passwd
3489           database.
3490
3491       "d_setpwent_r"
3492           From d_setpwent_r.U:
3493
3494           This variable conditionally defines the "HAS_SETPWENT_R" symbol,
3495           which indicates to the C program that the setpwent_r() routine is
3496           available.
3497
3498       "d_setregid"
3499           From d_setregid.U:
3500
3501           This variable conditionally defines "HAS_SETREGID" if setregid() is
3502           available to change the real and effective gid of the current
3503           process.
3504
3505       "d_setresgid"
3506           From d_setregid.U:
3507
3508           This variable conditionally defines "HAS_SETRESGID" if setresgid()
3509           is available to change the real, effective and saved gid of the
3510           current process.
3511
3512       "d_setresuid"
3513           From d_setreuid.U:
3514
3515           This variable conditionally defines "HAS_SETREUID" if setresuid()
3516           is available to change the real, effective and saved uid of the
3517           current process.
3518
3519       "d_setreuid"
3520           From d_setreuid.U:
3521
3522           This variable conditionally defines "HAS_SETREUID" if setreuid() is
3523           available to change the real and effective uid of the current
3524           process.
3525
3526       "d_setrgid"
3527           From d_setrgid.U:
3528
3529           This variable conditionally defines the "HAS_SETRGID" symbol, which
3530           indicates to the C program that the setrgid() routine is available
3531           to change the real gid of the current program.
3532
3533       "d_setruid"
3534           From d_setruid.U:
3535
3536           This variable conditionally defines the "HAS_SETRUID" symbol, which
3537           indicates to the C program that the setruid() routine is available
3538           to change the real uid of the current program.
3539
3540       "d_setsent"
3541           From d_setsent.U:
3542
3543           This variable conditionally defines "HAS_SETSERVENT" if
3544           setservent() is available.
3545
3546       "d_setservent_r"
3547           From d_setservent_r.U:
3548
3549           This variable conditionally defines the "HAS_SETSERVENT_R" symbol,
3550           which indicates to the C program that the setservent_r() routine is
3551           available.
3552
3553       "d_setsid"
3554           From d_setsid.U:
3555
3556           This variable conditionally defines "HAS_SETSID" if setsid() is
3557           available to set the process group "ID".
3558
3559       "d_setvbuf"
3560           From d_setvbuf.U:
3561
3562           This variable conditionally defines the "HAS_SETVBUF" symbol, which
3563           indicates to the C program that the setvbuf() routine is available
3564           to change buffering on an open stdio stream.
3565
3566       "d_shm"
3567           From d_shm.U:
3568
3569           This variable conditionally defines the "HAS_SHM" symbol, which
3570           indicates that the entire shm*(2) library is present.
3571
3572       "d_shmat"
3573           From d_shmat.U:
3574
3575           This variable conditionally defines the "HAS_SHMAT" symbol, which
3576           indicates to the C program that the shmat() routine is available.
3577
3578       "d_shmatprototype"
3579           From d_shmat.U:
3580
3581           This variable conditionally defines the "HAS_SHMAT_PROTOTYPE"
3582           symbol, which indicates that sys/shm.h has a prototype for shmat.
3583
3584       "d_shmctl"
3585           From d_shmctl.U:
3586
3587           This variable conditionally defines the "HAS_SHMCTL" symbol, which
3588           indicates to the C program that the shmctl() routine is available.
3589
3590       "d_shmdt"
3591           From d_shmdt.U:
3592
3593           This variable conditionally defines the "HAS_SHMDT" symbol, which
3594           indicates to the C program that the shmdt() routine is available.
3595
3596       "d_shmget"
3597           From d_shmget.U:
3598
3599           This variable conditionally defines the "HAS_SHMGET" symbol, which
3600           indicates to the C program that the shmget() routine is available.
3601
3602       "d_sigaction"
3603           From d_sigaction.U:
3604
3605           This variable conditionally defines the "HAS_SIGACTION" symbol,
3606           which indicates that the Vr4 sigaction() routine is available.
3607
3608       "d_siginfo_si_addr"
3609           From d_siginfo_si.U:
3610
3611           This variable conditionally defines the "HAS_SIGINFO_SI_ADDR"
3612           symbol, which indicates that the siginfo_t struct has the si_addr
3613           member.
3614
3615       "d_siginfo_si_band"
3616           From d_siginfo_si.U:
3617
3618           This variable conditionally defines the "HAS_SIGINFO_SI_BAND"
3619           symbol, which indicates that the siginfo_t struct has the si_band
3620           member.
3621
3622       "d_siginfo_si_errno"
3623           From d_siginfo_si.U:
3624
3625           This variable conditionally defines the "HAS_SIGINFO_SI_ERRNO"
3626           symbol, which indicates that the siginfo_t struct has the si_errno
3627           member.
3628
3629       "d_siginfo_si_fd"
3630           From d_siginfo_si.U:
3631
3632           This variable conditionally defines the "HAS_SIGINFO_SI_FD" symbol,
3633           which indicates that the siginfo_t struct has the si_fd member.
3634
3635       "d_siginfo_si_pid"
3636           From d_siginfo_si.U:
3637
3638           This variable conditionally defines the "HAS_SIGINFO_SI_PID"
3639           symbol, which indicates that the siginfo_t struct has the si_pid
3640           member.
3641
3642       "d_siginfo_si_status"
3643           From d_siginfo_si.U:
3644
3645           This variable conditionally defines the "HAS_SIGINFO_SI_STATUS"
3646           symbol, which indicates that the siginfo_t struct has the si_status
3647           member.
3648
3649       "d_siginfo_si_uid"
3650           From d_siginfo_si.U:
3651
3652           This variable conditionally defines the "HAS_SIGINFO_SI_UID"
3653           symbol, which indicates that the siginfo_t struct has the si_uid
3654           member.
3655
3656       "d_siginfo_si_value"
3657           From d_siginfo_si.U:
3658
3659           This variable conditionally defines the "HAS_SIGINFO_SI_VALUE"
3660           symbol, which indicates that the siginfo_t struct has the si_value
3661           member.
3662
3663       "d_signbit"
3664           From d_signbit.U:
3665
3666           This variable conditionally defines the "HAS_SIGNBIT" symbol, which
3667           indicates to the C program that the signbit() routine is available
3668           and safe to use with perl's intern "NV" type.
3669
3670       "d_sigprocmask"
3671           From d_sigprocmask.U:
3672
3673           This variable conditionally defines "HAS_SIGPROCMASK" if
3674           sigprocmask() is available to examine or change the signal mask of
3675           the calling process.
3676
3677       "d_sigsetjmp"
3678           From d_sigsetjmp.U:
3679
3680           This variable conditionally defines the "HAS_SIGSETJMP" symbol,
3681           which indicates that the sigsetjmp() routine is available to call
3682           setjmp() and optionally save the process's signal mask.
3683
3684       "d_sin6_scope_id"
3685           From d_socket.U:
3686
3687           This variable conditionally defines the HAS_SIN6_SCOPE_ID symbol,
3688           which indicates that a struct sockaddr_in6 structure has the
3689           sin6_scope_id member.
3690
3691       "d_sitearch"
3692           From sitearch.U:
3693
3694           This variable conditionally defines "SITEARCH" to hold the pathname
3695           of architecture-dependent library files for $package.  If $sitearch
3696           is the same as $archlib, then this is set to undef.
3697
3698       "d_snprintf"
3699           From d_snprintf.U:
3700
3701           This variable conditionally defines the "HAS_SNPRINTF" symbol,
3702           which indicates to the C program that the snprintf () library
3703           function is available.
3704
3705       "d_sockaddr_in6"
3706           From d_socket.U:
3707
3708           This variable conditionally defines the HAS_SOCKADDR_IN6 symbol,
3709           which indicates the availability of a struct sockaddr_in6.
3710
3711       "d_sockaddr_sa_len"
3712           From d_socket.U:
3713
3714           This variable conditionally defines the "HAS_SOCKADDR_SA_LEN"
3715           symbol, which indicates that a struct sockaddr structure has the
3716           sa_len member.
3717
3718       "d_sockatmark"
3719           From d_sockatmark.U:
3720
3721           This variable conditionally defines the "HAS_SOCKATMARK" symbol,
3722           which indicates to the C program that the sockatmark() routine is
3723           available.
3724
3725       "d_sockatmarkproto"
3726           From d_sockatmarkproto.U:
3727
3728           This variable conditionally defines the "HAS_SOCKATMARK_PROTO"
3729           symbol, which indicates to the C program that the system provides a
3730           prototype for the sockatmark() function.  Otherwise, it is up to
3731           the program to supply one.
3732
3733       "d_socket"
3734           From d_socket.U:
3735
3736           This variable conditionally defines "HAS_SOCKET", which indicates
3737           that the "BSD" socket interface is supported.
3738
3739       "d_socklen_t"
3740           From d_socklen_t.U:
3741
3742           This symbol will be defined if the C compiler supports socklen_t.
3743
3744       "d_sockpair"
3745           From d_socket.U:
3746
3747           This variable conditionally defines the "HAS_SOCKETPAIR" symbol,
3748           which indicates that the "BSD" socketpair() is supported.
3749
3750       "d_socks5_init"
3751           From d_socks5_init.U:
3752
3753           This variable conditionally defines the HAS_SOCKS5_INIT symbol,
3754           which indicates to the C program that the socks5_init() routine is
3755           available.
3756
3757       "d_sqrtl"
3758           From d_sqrtl.U:
3759
3760           This variable conditionally defines the "HAS_SQRTL" symbol, which
3761           indicates to the C program that the sqrtl() routine is available.
3762
3763       "d_srand48_r"
3764           From d_srand48_r.U:
3765
3766           This variable conditionally defines the HAS_SRAND48_R symbol, which
3767           indicates to the C program that the srand48_r() routine is
3768           available.
3769
3770       "d_srandom_r"
3771           From d_srandom_r.U:
3772
3773           This variable conditionally defines the "HAS_SRANDOM_R" symbol,
3774           which indicates to the C program that the srandom_r() routine is
3775           available.
3776
3777       "d_sresgproto"
3778           From d_sresgproto.U:
3779
3780           This variable conditionally defines the "HAS_SETRESGID_PROTO"
3781           symbol, which indicates to the C program that the system provides a
3782           prototype for the setresgid() function.  Otherwise, it is up to the
3783           program to supply one.
3784
3785       "d_sresuproto"
3786           From d_sresuproto.U:
3787
3788           This variable conditionally defines the "HAS_SETRESUID_PROTO"
3789           symbol, which indicates to the C program that the system provides a
3790           prototype for the setresuid() function.  Otherwise, it is up to the
3791           program to supply one.
3792
3793       "d_stat"
3794           From d_stat.U:
3795
3796           This variable conditionally defines "HAS_STAT" if stat() is
3797           available to get file status.
3798
3799       "d_statblks"
3800           From d_statblks.U:
3801
3802           This variable conditionally defines "USE_STAT_BLOCKS" if this
3803           system has a stat structure declaring st_blksize and st_blocks.
3804
3805       "d_statfs_f_flags"
3806           From d_statfs_f_flags.U:
3807
3808           This variable conditionally defines the "HAS_STRUCT_STATFS_F_FLAGS"
3809           symbol, which indicates to struct statfs from has f_flags member.
3810           This kind of struct statfs is coming from sys/mount.h ("BSD"), not
3811           from sys/statfs.h ("SYSV").
3812
3813       "d_statfs_s"
3814           From d_statfs_s.U:
3815
3816           This variable conditionally defines the "HAS_STRUCT_STATFS" symbol,
3817           which indicates that the struct statfs is supported.
3818
3819       "d_static_inline"
3820           From d_static_inline.U:
3821
3822           This variable conditionally defines the "HAS_STATIC_INLINE" symbol,
3823           which indicates that the C compiler supports C99-style static
3824           inline.  That is, the function can't be called from another
3825           translation unit.
3826
3827       "d_statvfs"
3828           From d_statvfs.U:
3829
3830           This variable conditionally defines the "HAS_STATVFS" symbol, which
3831           indicates to the C program that the statvfs() routine is available.
3832
3833       "d_stdio_cnt_lval"
3834           From d_stdstdio.U:
3835
3836           This variable conditionally defines "STDIO_CNT_LVALUE" if the
3837           "FILE_cnt" macro can be used as an lvalue.
3838
3839       "d_stdio_ptr_lval"
3840           From d_stdstdio.U:
3841
3842           This variable conditionally defines "STDIO_PTR_LVALUE" if the
3843           "FILE_ptr" macro can be used as an lvalue.
3844
3845       "d_stdio_ptr_lval_nochange_cnt"
3846           From d_stdstdio.U:
3847
3848           This symbol is defined if using the "FILE_ptr" macro as an lvalue
3849           to increase the pointer by n leaves File_cnt(fp) unchanged.
3850
3851       "d_stdio_ptr_lval_sets_cnt"
3852           From d_stdstdio.U:
3853
3854           This symbol is defined if using the "FILE_ptr" macro as an lvalue
3855           to increase the pointer by n has the side effect of decreasing the
3856           value of File_cnt(fp) by n.
3857
3858       "d_stdio_stream_array"
3859           From stdio_streams.U:
3860
3861           This variable tells whether there is an array holding the stdio
3862           streams.
3863
3864       "d_stdiobase"
3865           From d_stdstdio.U:
3866
3867           This variable conditionally defines "USE_STDIO_BASE" if this system
3868           has a "FILE" structure declaring a usable _base field (or
3869           equivalent) in stdio.h.
3870
3871       "d_stdstdio"
3872           From d_stdstdio.U:
3873
3874           This variable conditionally defines "USE_STDIO_PTR" if this system
3875           has a "FILE" structure declaring usable _ptr and _cnt fields (or
3876           equivalent) in stdio.h.
3877
3878       "d_strcoll"
3879           From d_strcoll.U:
3880
3881           This variable conditionally defines "HAS_STRCOLL" if strcoll() is
3882           available to compare strings using collating information.
3883
3884       "d_strerror_l"
3885           From d_strerror_l.U:
3886
3887           This variable conditionally defines the "HAS_STRERROR_L" symbol,
3888           which indicates to the C program that the strerror_l() routine is
3889           available to return the error message for a given errno value in a
3890           particular locale (identified by a locale_t object).
3891
3892       "d_strerror_r"
3893           From d_strerror_r.U:
3894
3895           This variable conditionally defines the "HAS_STRERROR_R" symbol,
3896           which indicates to the C program that the strerror_r() routine is
3897           available.
3898
3899       "d_strftime"
3900           From d_strftime.U:
3901
3902           This variable conditionally defines the "HAS_STRFTIME" symbol,
3903           which indicates to the C program that the strftime() routine is
3904           available.
3905
3906       "d_strlcat"
3907           From d_strlcat.U:
3908
3909           This variable conditionally defines the "HAS_STRLCAT" symbol, which
3910           indicates to the C program that the strlcat () routine is
3911           available.
3912
3913       "d_strlcpy"
3914           From d_strlcpy.U:
3915
3916           This variable conditionally defines the "HAS_STRLCPY" symbol, which
3917           indicates to the C program that the strlcpy () routine is
3918           available.
3919
3920       "d_strnlen"
3921           From d_strnlen.U:
3922
3923           This variable conditionally defines the "HAS_STRNLEN" symbol, which
3924           indicates to the C program that the strnlen () routine is
3925           available.
3926
3927       "d_strtod"
3928           From d_strtod.U:
3929
3930           This variable conditionally defines the "HAS_STRTOD" symbol, which
3931           indicates to the C program that the strtod() routine is available
3932           to provide better numeric string conversion than atof().
3933
3934       "d_strtod_l"
3935           From d_strtod_l.U:
3936
3937           This variable conditionally defines the "HAS_STRTOD_L" symbol,
3938           which indicates to the C program that the strtod_l() routine is
3939           available.
3940
3941       "d_strtol"
3942           From d_strtol.U:
3943
3944           This variable conditionally defines the "HAS_STRTOL" symbol, which
3945           indicates to the C program that the strtol() routine is available
3946           to provide better numeric string conversion than atoi() and
3947           friends.
3948
3949       "d_strtold"
3950           From d_strtold.U:
3951
3952           This variable conditionally defines the "HAS_STRTOLD" symbol, which
3953           indicates to the C program that the strtold() routine is available.
3954
3955       "d_strtold_l"
3956           From d_strtold_l.U:
3957
3958           This variable conditionally defines the "HAS_STRTOLD_L" symbol,
3959           which indicates to the C program that the strtold_l() routine is
3960           available.
3961
3962       "d_strtoll"
3963           From d_strtoll.U:
3964
3965           This variable conditionally defines the "HAS_STRTOLL" symbol, which
3966           indicates to the C program that the strtoll() routine is available.
3967
3968       "d_strtoq"
3969           From d_strtoq.U:
3970
3971           This variable conditionally defines the "HAS_STRTOQ" symbol, which
3972           indicates to the C program that the strtoq() routine is available.
3973
3974       "d_strtoul"
3975           From d_strtoul.U:
3976
3977           This variable conditionally defines the "HAS_STRTOUL" symbol, which
3978           indicates to the C program that the strtoul() routine is available
3979           to provide conversion of strings to unsigned long.
3980
3981       "d_strtoull"
3982           From d_strtoull.U:
3983
3984           This variable conditionally defines the "HAS_STRTOULL" symbol,
3985           which indicates to the C program that the strtoull() routine is
3986           available.
3987
3988       "d_strtouq"
3989           From d_strtouq.U:
3990
3991           This variable conditionally defines the "HAS_STRTOUQ" symbol, which
3992           indicates to the C program that the strtouq() routine is available.
3993
3994       "d_strxfrm"
3995           From d_strxfrm.U:
3996
3997           This variable conditionally defines "HAS_STRXFRM" if strxfrm() is
3998           available to transform strings.
3999
4000       "d_suidsafe"
4001           From d_dosuid.U:
4002
4003           This variable conditionally defines "SETUID_SCRIPTS_ARE_SECURE_NOW"
4004           if setuid scripts can be secure.  This test looks in /dev/fd/.
4005
4006       "d_symlink"
4007           From d_symlink.U:
4008
4009           This variable conditionally defines the "HAS_SYMLINK" symbol, which
4010           indicates to the C program that the symlink() routine is available
4011           to create symbolic links.
4012
4013       "d_syscall"
4014           From d_syscall.U:
4015
4016           This variable conditionally defines "HAS_SYSCALL" if syscall() is
4017           available call arbitrary system calls.
4018
4019       "d_syscallproto"
4020           From d_syscallproto.U:
4021
4022           This variable conditionally defines the "HAS_SYSCALL_PROTO" symbol,
4023           which indicates to the C program that the system provides a
4024           prototype for the syscall() function.  Otherwise, it is up to the
4025           program to supply one.
4026
4027       "d_sysconf"
4028           From d_sysconf.U:
4029
4030           This variable conditionally defines the "HAS_SYSCONF" symbol, which
4031           indicates to the C program that the sysconf() routine is available
4032           to determine system related limits and options.
4033
4034       "d_sysernlst"
4035           From d_strerror.U:
4036
4037           This variable conditionally defines "HAS_SYS_ERRNOLIST" if
4038           sys_errnolist[] is available to translate error numbers to the
4039           symbolic name.
4040
4041       "d_syserrlst"
4042           From d_strerror.U:
4043
4044           This variable conditionally defines "HAS_SYS_ERRLIST" if
4045           sys_errlist[] is available to translate error numbers to strings.
4046
4047       "d_system"
4048           From d_system.U:
4049
4050           This variable conditionally defines "HAS_SYSTEM" if system() is
4051           available to issue a shell command.
4052
4053       "d_tcgetpgrp"
4054           From d_tcgtpgrp.U:
4055
4056           This variable conditionally defines the "HAS_TCGETPGRP" symbol,
4057           which indicates to the C program that the tcgetpgrp() routine is
4058           available.  to get foreground process group "ID".
4059
4060       "d_tcsetpgrp"
4061           From d_tcstpgrp.U:
4062
4063           This variable conditionally defines the "HAS_TCSETPGRP" symbol,
4064           which indicates to the C program that the tcsetpgrp() routine is
4065           available to set foreground process group "ID".
4066
4067       "d_telldir"
4068           From d_readdir.U:
4069
4070           This variable conditionally defines "HAS_TELLDIR" if telldir() is
4071           available.
4072
4073       "d_telldirproto"
4074           From d_telldirproto.U:
4075
4076           This variable conditionally defines the "HAS_TELLDIR_PROTO" symbol,
4077           which indicates to the C program that the system provides a
4078           prototype for the telldir() function.  Otherwise, it is up to the
4079           program to supply one.
4080
4081       "d_tgamma"
4082           From d_tgamma.U:
4083
4084           This variable conditionally defines the "HAS_TGAMMA" symbol, which
4085           indicates to the C program that the tgamma() routine is available
4086           for the gamma function.  See also d_lgamma.
4087
4088       "d_thread_safe_nl_langinfo_l"
4089           From d_nl_langinfo_l.U:
4090
4091           This variable contains the eventual value of the
4092           "HAS_THREAD_SAFE_NL_LANGINFO_L" symbol, which indicates if the
4093           nl_langinfo_l() function exists and is thread-safe.
4094
4095       "d_time"
4096           From d_time.U:
4097
4098           This variable conditionally defines the "HAS_TIME" symbol, which
4099           indicates that the time() routine exists.  The time() routine is
4100           normally provided on "UNIX" systems.
4101
4102       "d_timegm"
4103           From d_timegm.U:
4104
4105           This variable conditionally defines the "HAS_TIMEGM" symbol, which
4106           indicates to the C program that the timegm () routine is available.
4107
4108       "d_times"
4109           From d_times.U:
4110
4111           This variable conditionally defines the "HAS_TIMES" symbol, which
4112           indicates that the times() routine exists.  The times() routine is
4113           normally provided on "UNIX" systems. You may have to include
4114           <sys/times.h>.
4115
4116       "d_tm_tm_gmtoff"
4117           From i_time.U:
4118
4119           This variable conditionally defines "HAS_TM_TM_GMTOFF", which
4120           indicates to the C program that the struct tm has the tm_gmtoff
4121           field.
4122
4123       "d_tm_tm_zone"
4124           From i_time.U:
4125
4126           This variable conditionally defines "HAS_TM_TM_ZONE", which
4127           indicates to the C program that the struct tm has the tm_zone
4128           field.
4129
4130       "d_tmpnam_r"
4131           From d_tmpnam_r.U:
4132
4133           This variable conditionally defines the "HAS_TMPNAM_R" symbol,
4134           which indicates to the C program that the tmpnam_r() routine is
4135           available.
4136
4137       "d_towlower"
4138           From d_towlower.U:
4139
4140           This variable conditionally defines the "HAS_TOWLOWER" symbol,
4141           which indicates to the C program that the towlower() routine is
4142           available.
4143
4144       "d_towupper"
4145           From d_towupper.U:
4146
4147           This variable conditionally defines the "HAS_TOWUPPER" symbol,
4148           which indicates to the C program that the towupper() routine is
4149           available.
4150
4151       "d_trunc"
4152           From d_trunc.U:
4153
4154           This variable conditionally defines the "HAS_TRUNC" symbol, which
4155           indicates to the C program that the trunc() routine is available to
4156           round doubles towards zero.
4157
4158       "d_truncate"
4159           From d_truncate.U:
4160
4161           This variable conditionally defines "HAS_TRUNCATE" if truncate() is
4162           available to truncate files.
4163
4164       "d_truncl"
4165           From d_truncl.U:
4166
4167           This variable conditionally defines the "HAS_TRUNCL" symbol, which
4168           indicates to the C program that the truncl() routine is available
4169           to round long doubles towards zero. If copysignl is also present,
4170           we can emulate modfl.
4171
4172       "d_ttyname_r"
4173           From d_ttyname_r.U:
4174
4175           This variable conditionally defines the "HAS_TTYNAME_R" symbol,
4176           which indicates to the C program that the ttyname_r() routine is
4177           available.
4178
4179       "d_tzname"
4180           From d_tzname.U:
4181
4182           This variable conditionally defines "HAS_TZNAME" if tzname[] is
4183           available to access timezone names.
4184
4185       "d_u32align"
4186           From d_u32align.U:
4187
4188           This variable tells whether you must access character data through
4189           U32-aligned pointers.
4190
4191       "d_ualarm"
4192           From d_ualarm.U:
4193
4194           This variable conditionally defines the "HAS_UALARM" symbol, which
4195           indicates to the C program that the ualarm() routine is available.
4196
4197       "d_umask"
4198           From d_umask.U:
4199
4200           This variable conditionally defines the "HAS_UMASK" symbol, which
4201           indicates to the C program that the umask() routine is available.
4202           to set and get the value of the file creation mask.
4203
4204       "d_uname"
4205           From d_gethname.U:
4206
4207           This variable conditionally defines the "HAS_UNAME" symbol, which
4208           indicates to the C program that the uname() routine may be used to
4209           derive the host name.
4210
4211       "d_union_semun"
4212           From d_union_semun.U:
4213
4214           This variable conditionally defines "HAS_UNION_SEMUN" if the union
4215           semun is defined by including <sys/sem.h>.
4216
4217       "d_unlinkat"
4218           From d_fsat.U:
4219
4220           This variable conditionally defines the "HAS_UNLINKAT" symbol,
4221           which indicates the "POSIX" unlinkat() function isavailable.
4222
4223       "d_unordered"
4224           From d_unordered.U:
4225
4226           This variable conditionally defines the "HAS_UNORDERED" symbol,
4227           which indicates to the C program that the unordered() routine is
4228           available.
4229
4230       "d_unsetenv"
4231           From d_unsetenv.U:
4232
4233           This variable conditionally defines the "HAS_UNSETENV" symbol,
4234           which indicates to the C program that the unsetenv () routine is
4235           available.
4236
4237       "d_uselocale"
4238           From d_newlocale.U:
4239
4240           This variable conditionally defines the "HAS_USELOCALE" symbol,
4241           which indicates to the C program that the uselocale() routine is
4242           available to set the current locale for the calling thread.
4243
4244       "d_usleep"
4245           From d_usleep.U:
4246
4247           This variable conditionally defines "HAS_USLEEP" if usleep() is
4248           available to do high granularity sleeps.
4249
4250       "d_usleepproto"
4251           From d_usleepproto.U:
4252
4253           This variable conditionally defines the "HAS_USLEEP_PROTO" symbol,
4254           which indicates to the C program that the system provides a
4255           prototype for the usleep() function.  Otherwise, it is up to the
4256           program to supply one.
4257
4258       "d_ustat"
4259           From d_ustat.U:
4260
4261           This variable conditionally defines "HAS_USTAT" if ustat() is
4262           available to query file system statistics by dev_t.
4263
4264       "d_vendorarch"
4265           From vendorarch.U:
4266
4267           This variable conditionally defined "PERL_VENDORARCH".
4268
4269       "d_vendorbin"
4270           From vendorbin.U:
4271
4272           This variable conditionally defines "PERL_VENDORBIN".
4273
4274       "d_vendorlib"
4275           From vendorlib.U:
4276
4277           This variable conditionally defines "PERL_VENDORLIB".
4278
4279       "d_vendorscript"
4280           From vendorscript.U:
4281
4282           This variable conditionally defines "PERL_VENDORSCRIPT".
4283
4284       "d_vfork"
4285           From d_vfork.U:
4286
4287           This variable conditionally defines the "HAS_VFORK" symbol, which
4288           indicates the vfork() routine is available.
4289
4290       "d_void_closedir"
4291           From d_closedir.U:
4292
4293           This variable conditionally defines "VOID_CLOSEDIR" if closedir()
4294           does not return a value.
4295
4296       "d_voidsig"
4297           From d_voidsig.U:
4298
4299           This variable conditionally defines "VOIDSIG" if this system
4300           declares "void (*signal(...))()" in signal.h.  The old way was to
4301           declare it as "int (*signal(...))()".
4302
4303       "d_voidtty"
4304           From i_sysioctl.U:
4305
4306           This variable conditionally defines "USE_IOCNOTTY" to indicate that
4307           the ioctl() call with "TIOCNOTTY" should be used to void tty
4308           association.  Otherwise (on "USG" probably), it is enough to close
4309           the standard file descriptors and do a setpgrp().
4310
4311       "d_vsnprintf"
4312           From d_snprintf.U:
4313
4314           This variable conditionally defines the "HAS_VSNPRINTF" symbol,
4315           which indicates to the C program that the vsnprintf () library
4316           function is available.
4317
4318       "d_wait4"
4319           From d_wait4.U:
4320
4321           This variable conditionally defines the HAS_WAIT4 symbol, which
4322           indicates the wait4() routine is available.
4323
4324       "d_waitpid"
4325           From d_waitpid.U:
4326
4327           This variable conditionally defines "HAS_WAITPID" if waitpid() is
4328           available to wait for child process.
4329
4330       "d_wcscmp"
4331           From d_wcscmp.U:
4332
4333           This variable conditionally defines the "HAS_WCSCMP" symbol if the
4334           wcscmp() routine is available and can be used to compare wide
4335           character strings.
4336
4337       "d_wcstombs"
4338           From d_wcstombs.U:
4339
4340           This variable conditionally defines the "HAS_WCSTOMBS" symbol,
4341           which indicates to the C program that the wcstombs() routine is
4342           available to convert wide character strings to multibyte strings.
4343
4344       "d_wcsxfrm"
4345           From d_wcsxfrm.U:
4346
4347           This variable conditionally defines the "HAS_WCSXFRM" symbol if the
4348           wcsxfrm() routine is available and can be used to compare wide
4349           character strings.
4350
4351       "d_wctomb"
4352           From d_wctomb.U:
4353
4354           This variable conditionally defines the "HAS_WCTOMB" symbol, which
4355           indicates to the C program that the wctomb() routine is available
4356           to convert a wide character to a multibyte.
4357
4358       "d_writev"
4359           From d_writev.U:
4360
4361           This variable conditionally defines the "HAS_WRITEV" symbol, which
4362           indicates to the C program that the writev() routine is available.
4363
4364       "d_xenix"
4365           From Guess.U:
4366
4367           This variable conditionally defines the symbol "XENIX", which
4368           alerts the C program that it runs under Xenix.
4369
4370       "date"
4371           From Loc.U:
4372
4373           This variable is used internally by Configure to determine the full
4374           pathname (if any) of the date program.  After Configure runs, the
4375           value is reset to a plain "date" and is not useful.
4376
4377       "db_hashtype"
4378           From i_db.U:
4379
4380           This variable contains the type of the hash structure element in
4381           the <db.h> header file.  In older versions of "DB", it was int,
4382           while in newer ones it is u_int32_t.
4383
4384       "db_prefixtype"
4385           From i_db.U:
4386
4387           This variable contains the type of the prefix structure element in
4388           the <db.h> header file.  In older versions of "DB", it was int,
4389           while in newer ones it is size_t.
4390
4391       "db_version_major"
4392           From i_db.U:
4393
4394           This variable contains the major version number of Berkeley "DB"
4395           found in the <db.h> header file.
4396
4397       "db_version_minor"
4398           From i_db.U:
4399
4400           This variable contains the minor version number of Berkeley "DB"
4401           found in the <db.h> header file.  For "DB" version 1 this is always
4402           0.
4403
4404       "db_version_patch"
4405           From i_db.U:
4406
4407           This variable contains the patch version number of Berkeley "DB"
4408           found in the <db.h> header file.  For "DB" version 1 this is always
4409           0.
4410
4411       "default_inc_excludes_dot"
4412           From defaultincdot.U:
4413
4414           When defined, remove the legacy . from @"INC"
4415
4416       "direntrytype"
4417           From i_dirent.U:
4418
4419           This symbol is set to "struct direct" or "struct dirent" depending
4420           on whether dirent is available or not. You should use this pseudo
4421           type to portably declare your directory entries.
4422
4423       "dlext"
4424           From dlext.U:
4425
4426           This variable contains the extension that is to be used for the
4427           dynamically loaded modules that perl generates.
4428
4429       "dlsrc"
4430           From dlsrc.U:
4431
4432           This variable contains the name of the dynamic loading file that
4433           will be used with the package.
4434
4435       "doubleinfbytes"
4436           From infnan.U:
4437
4438           This variable contains comma-separated list of hexadecimal bytes
4439           for the double precision infinity.
4440
4441       "doublekind"
4442           From longdblfio.U:
4443
4444           This variable, if defined, encodes the type of a double: 1 = "IEEE"
4445           754 32-bit little endian, 2 = "IEEE" 754 32-bit big endian, 3 =
4446           "IEEE" 754 64-bit little endian, 4 = "IEEE" 754 64-bit big endian,
4447           5 = "IEEE" 754 128-bit little endian, 6 = "IEEE" 754 128-bit big
4448           endian, 7 = "IEEE" 754 64-bit mixed endian le-be, 8 = "IEEE" 754
4449           64-bit mixed endian be-le, 9 = "VAX" 32bit little endian F float
4450           format 10 = "VAX" 64bit little endian D float format 11 = "VAX"
4451           64bit little endian G float format 12 = "IBM" 32bit format 13 =
4452           "IBM" 64bit format 14 = Cray 64bit format -1 = unknown format.
4453
4454       "doublemantbits"
4455           From mantbits.U:
4456
4457           This symbol, if defined, tells how many mantissa bits there are in
4458           double precision floating point format.  Note that this is usually
4459           "DBL_MANT_DIG" minus one, since with the standard "IEEE" 754
4460           formats "DBL_MANT_DIG" includes the implicit bit which doesn't
4461           really exist.
4462
4463       "doublenanbytes"
4464           From infnan.U:
4465
4466           This variable contains comma-separated list of hexadecimal bytes
4467           for the double precision not-a-number.
4468
4469       "doublesize"
4470           From doublesize.U:
4471
4472           This variable contains the value of the "DOUBLESIZE" symbol, which
4473           indicates to the C program how many bytes there are in a double.
4474
4475       "drand01"
4476           From randfunc.U:
4477
4478           Indicates the macro to be used to generate normalized random
4479           numbers.  Uses randfunc, often divided by (double) (((unsigned
4480           long) 1 << randbits)) in order to normalize the result.  In C
4481           programs, the macro "Drand01" is mapped to drand01.
4482
4483       "drand48_r_proto"
4484           From d_drand48_r.U:
4485
4486           This variable encodes the prototype of drand48_r.  It is zero if
4487           d_drand48_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
4488           of reentr.h if d_drand48_r is defined.
4489
4490       "dtrace"
4491           From usedtrace.U:
4492
4493           This variable holds the location of the dtrace executable.
4494
4495       "dtraceobject"
4496           From dtraceobject.U:
4497
4498           Whether we need to build an object file with the dtrace tool.
4499
4500       "dtracexnolibs"
4501           From dtraceobject.U:
4502
4503           Whether dtrace accepts -xnolibs.  If available we call dtrace -h
4504           and dtrace -G with -xnolibs to allow dtrace to run in a jail on
4505           FreeBSD.
4506
4507       "dynamic_ext"
4508           From Extensions.U:
4509
4510           This variable holds a list of "XS" extension files we want to link
4511           dynamically into the package.  It is used by Makefile.
4512
4513   e
4514       "eagain"
4515           From nblock_io.U:
4516
4517           This variable bears the symbolic errno code set by read() when no
4518           data is present on the file and non-blocking I/O was enabled
4519           (otherwise, read() blocks naturally).
4520
4521       "ebcdic"
4522           From ebcdic.U:
4523
4524           This variable conditionally defines "EBCDIC" if this system uses
4525           "EBCDIC" encoding.
4526
4527       "echo"
4528           From Loc.U:
4529
4530           This variable is used internally by Configure to determine the full
4531           pathname (if any) of the echo program.  After Configure runs, the
4532           value is reset to a plain "echo" and is not useful.
4533
4534       "egrep"
4535           From Loc.U:
4536
4537           This variable is used internally by Configure to determine the full
4538           pathname (if any) of the egrep program.  After Configure runs, the
4539           value is reset to a plain "egrep" and is not useful.
4540
4541       "emacs"
4542           From Loc.U:
4543
4544           This variable is defined but not used by Configure.  The value is
4545           the empty string and is not useful.
4546
4547       "endgrent_r_proto"
4548           From d_endgrent_r.U:
4549
4550           This variable encodes the prototype of endgrent_r.  It is zero if
4551           d_endgrent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4552           macros of reentr.h if d_endgrent_r is defined.
4553
4554       "endhostent_r_proto"
4555           From d_endhostent_r.U:
4556
4557           This variable encodes the prototype of endhostent_r.  It is zero if
4558           d_endhostent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4559           macros of reentr.h if d_endhostent_r is defined.
4560
4561       "endnetent_r_proto"
4562           From d_endnetent_r.U:
4563
4564           This variable encodes the prototype of endnetent_r.  It is zero if
4565           d_endnetent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4566           macros of reentr.h if d_endnetent_r is defined.
4567
4568       "endprotoent_r_proto"
4569           From d_endprotoent_r.U:
4570
4571           This variable encodes the prototype of endprotoent_r.  It is zero
4572           if d_endprotoent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4573           macros of reentr.h if d_endprotoent_r is defined.
4574
4575       "endpwent_r_proto"
4576           From d_endpwent_r.U:
4577
4578           This variable encodes the prototype of endpwent_r.  It is zero if
4579           d_endpwent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4580           macros of reentr.h if d_endpwent_r is defined.
4581
4582       "endservent_r_proto"
4583           From d_endservent_r.U:
4584
4585           This variable encodes the prototype of endservent_r.  It is zero if
4586           d_endservent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4587           macros of reentr.h if d_endservent_r is defined.
4588
4589       "eunicefix"
4590           From Init.U:
4591
4592           When running under Eunice this variable contains a command which
4593           will convert a shell script to the proper form of text file for it
4594           to be executable by the shell.  On other systems it is a no-op.
4595
4596       "exe_ext"
4597           From Unix.U:
4598
4599           This is an old synonym for _exe.
4600
4601       "expr"
4602           From Loc.U:
4603
4604           This variable is used internally by Configure to determine the full
4605           pathname (if any) of the expr program.  After Configure runs, the
4606           value is reset to a plain "expr" and is not useful.
4607
4608       "extensions"
4609           From Extensions.U:
4610
4611           This variable holds a list of all extension files (both "XS" and
4612           non-xs) installed with the package.  It is propagated to Config.pm
4613           and is typically used to test whether a particular extension is
4614           available.
4615
4616       "extern_C"
4617           From Csym.U:
4618
4619           "ANSI" C requires "extern" where C++ requires 'extern "C"'. This
4620           variable can be used in Configure to do the right thing.
4621
4622       "extras"
4623           From Extras.U:
4624
4625           This variable holds a list of extra modules to install.
4626
4627   f
4628       "fflushall"
4629           From fflushall.U:
4630
4631           This symbol, if defined, tells that to flush all pending stdio
4632           output one must loop through all the stdio file handles stored in
4633           an array and fflush them.  Note that if fflushNULL is defined,
4634           fflushall will not even be probed for and will be left undefined.
4635
4636       "fflushNULL"
4637           From fflushall.U:
4638
4639           This symbol, if defined, tells that fflush("NULL") correctly
4640           flushes all pending stdio output without side effects. In
4641           particular, on some platforms calling fflush("NULL") *still*
4642           corrupts "STDIN" if it is a pipe.
4643
4644       "find"
4645           From Loc.U:
4646
4647           This variable is defined but not used by Configure.  The value is
4648           the empty string and is not useful.
4649
4650       "firstmakefile"
4651           From Unix.U:
4652
4653           This variable defines the first file searched by make.  On unix, it
4654           is makefile (then Makefile).  On case-insensitive systems, it might
4655           be something else.  This is only used to deal with convoluted make
4656           depend tricks.
4657
4658       "flex"
4659           From Loc.U:
4660
4661           This variable is defined but not used by Configure.  The value is
4662           the empty string and is not useful.
4663
4664       "fpossize"
4665           From fpossize.U:
4666
4667           This variable contains the size of a fpostype in bytes.
4668
4669       "fpostype"
4670           From fpostype.U:
4671
4672           This variable defines Fpos_t to be something like fpos_t, long,
4673           uint, or whatever type is used to declare file positions in libc.
4674
4675       "freetype"
4676           From mallocsrc.U:
4677
4678           This variable contains the return type of free().  It is usually
4679           void, but occasionally int.
4680
4681       "from"
4682           From Cross.U:
4683
4684           This variable contains the command used by Configure to copy files
4685           from the target host.  Useful and available only during Perl build.
4686           The string ":" if not cross-compiling.
4687
4688       "full_ar"
4689           From Loc_ar.U:
4690
4691           This variable contains the full pathname to "ar", whether or not
4692           the user has specified "portability".  This is only used in the
4693           Makefile.SH.
4694
4695       "full_csh"
4696           From d_csh.U:
4697
4698           This variable contains the full pathname to "csh", whether or not
4699           the user has specified "portability".  This is only used in the
4700           compiled C program, and we assume that all systems which can share
4701           this executable will have the same full pathname to csh.
4702
4703       "full_sed"
4704           From Loc_sed.U:
4705
4706           This variable contains the full pathname to "sed", whether or not
4707           the user has specified "portability".  This is only used in the
4708           compiled C program, and we assume that all systems which can share
4709           this executable will have the same full pathname to sed.
4710
4711   g
4712       "gccansipedantic"
4713           From gccvers.U:
4714
4715           If "GNU" cc (gcc) is used, this variable will enable (if set) the
4716           -ansi and -pedantic ccflags for building core files (through cflags
4717           script). (See Porting/pumpkin.pod for full description).
4718
4719       "gccosandvers"
4720           From gccvers.U:
4721
4722           If "GNU" cc (gcc) is used, this variable holds the operating system
4723           and version used to compile gcc.  It is set to '' if not gcc, or if
4724           nothing useful can be parsed as the os version.
4725
4726       "gccversion"
4727           From gccvers.U:
4728
4729           If "GNU" cc (gcc) is used, this variable holds 1 or 2 to indicate
4730           whether the compiler is version 1 or 2.  This is used in setting
4731           some of the default cflags.  It is set to '' if not gcc.
4732
4733       "getgrent_r_proto"
4734           From d_getgrent_r.U:
4735
4736           This variable encodes the prototype of getgrent_r.  It is zero if
4737           d_getgrent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4738           macros of reentr.h if d_getgrent_r is defined.
4739
4740       "getgrgid_r_proto"
4741           From d_getgrgid_r.U:
4742
4743           This variable encodes the prototype of getgrgid_r.  It is zero if
4744           d_getgrgid_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4745           macros of reentr.h if d_getgrgid_r is defined.
4746
4747       "getgrnam_r_proto"
4748           From d_getgrnam_r.U:
4749
4750           This variable encodes the prototype of getgrnam_r.  It is zero if
4751           d_getgrnam_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4752           macros of reentr.h if d_getgrnam_r is defined.
4753
4754       "gethostbyaddr_r_proto"
4755           From d_gethostbyaddr_r.U:
4756
4757           This variable encodes the prototype of gethostbyaddr_r.  It is zero
4758           if d_gethostbyaddr_r is undef, and one of the
4759           "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_gethostbyaddr_r is
4760           defined.
4761
4762       "gethostbyname_r_proto"
4763           From d_gethostbyname_r.U:
4764
4765           This variable encodes the prototype of gethostbyname_r.  It is zero
4766           if d_gethostbyname_r is undef, and one of the
4767           "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_gethostbyname_r is
4768           defined.
4769
4770       "gethostent_r_proto"
4771           From d_gethostent_r.U:
4772
4773           This variable encodes the prototype of gethostent_r.  It is zero if
4774           d_gethostent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4775           macros of reentr.h if d_gethostent_r is defined.
4776
4777       "getlogin_r_proto"
4778           From d_getlogin_r.U:
4779
4780           This variable encodes the prototype of getlogin_r.  It is zero if
4781           d_getlogin_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4782           macros of reentr.h if d_getlogin_r is defined.
4783
4784       "getnetbyaddr_r_proto"
4785           From d_getnetbyaddr_r.U:
4786
4787           This variable encodes the prototype of getnetbyaddr_r.  It is zero
4788           if d_getnetbyaddr_r is undef, and one of the
4789           "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getnetbyaddr_r is
4790           defined.
4791
4792       "getnetbyname_r_proto"
4793           From d_getnetbyname_r.U:
4794
4795           This variable encodes the prototype of getnetbyname_r.  It is zero
4796           if d_getnetbyname_r is undef, and one of the
4797           "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getnetbyname_r is
4798           defined.
4799
4800       "getnetent_r_proto"
4801           From d_getnetent_r.U:
4802
4803           This variable encodes the prototype of getnetent_r.  It is zero if
4804           d_getnetent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4805           macros of reentr.h if d_getnetent_r is defined.
4806
4807       "getprotobyname_r_proto"
4808           From d_getprotobyname_r.U:
4809
4810           This variable encodes the prototype of getprotobyname_r.  It is
4811           zero if d_getprotobyname_r is undef, and one of the
4812           "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getprotobyname_r is
4813           defined.
4814
4815       "getprotobynumber_r_proto"
4816           From d_getprotobynumber_r.U:
4817
4818           This variable encodes the prototype of getprotobynumber_r.  It is
4819           zero if d_getprotobynumber_r is undef, and one of the
4820           "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getprotobynumber_r
4821           is defined.
4822
4823       "getprotoent_r_proto"
4824           From d_getprotoent_r.U:
4825
4826           This variable encodes the prototype of getprotoent_r.  It is zero
4827           if d_getprotoent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4828           macros of reentr.h if d_getprotoent_r is defined.
4829
4830       "getpwent_r_proto"
4831           From d_getpwent_r.U:
4832
4833           This variable encodes the prototype of getpwent_r.  It is zero if
4834           d_getpwent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4835           macros of reentr.h if d_getpwent_r is defined.
4836
4837       "getpwnam_r_proto"
4838           From d_getpwnam_r.U:
4839
4840           This variable encodes the prototype of getpwnam_r.  It is zero if
4841           d_getpwnam_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4842           macros of reentr.h if d_getpwnam_r is defined.
4843
4844       "getpwuid_r_proto"
4845           From d_getpwuid_r.U:
4846
4847           This variable encodes the prototype of getpwuid_r.  It is zero if
4848           d_getpwuid_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4849           macros of reentr.h if d_getpwuid_r is defined.
4850
4851       "getservbyname_r_proto"
4852           From d_getservbyname_r.U:
4853
4854           This variable encodes the prototype of getservbyname_r.  It is zero
4855           if d_getservbyname_r is undef, and one of the
4856           "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getservbyname_r is
4857           defined.
4858
4859       "getservbyport_r_proto"
4860           From d_getservbyport_r.U:
4861
4862           This variable encodes the prototype of getservbyport_r.  It is zero
4863           if d_getservbyport_r is undef, and one of the
4864           "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getservbyport_r is
4865           defined.
4866
4867       "getservent_r_proto"
4868           From d_getservent_r.U:
4869
4870           This variable encodes the prototype of getservent_r.  It is zero if
4871           d_getservent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4872           macros of reentr.h if d_getservent_r is defined.
4873
4874       "getspnam_r_proto"
4875           From d_getspnam_r.U:
4876
4877           This variable encodes the prototype of getspnam_r.  It is zero if
4878           d_getspnam_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
4879           macros of reentr.h if d_getspnam_r is defined.
4880
4881       "gidformat"
4882           From gidf.U:
4883
4884           This variable contains the format string used for printing a Gid_t.
4885
4886       "gidsign"
4887           From gidsign.U:
4888
4889           This variable contains the signedness of a gidtype.  1 for
4890           unsigned, -1 for signed.
4891
4892       "gidsize"
4893           From gidsize.U:
4894
4895           This variable contains the size of a gidtype in bytes.
4896
4897       "gidtype"
4898           From gidtype.U:
4899
4900           This variable defines Gid_t to be something like gid_t, int,
4901           ushort, or whatever type is used to declare the return type of
4902           getgid().  Typically, it is the type of group ids in the kernel.
4903
4904       "glibpth"
4905           From libpth.U:
4906
4907           This variable holds the general path (space-separated) used to find
4908           libraries.  It may contain directories that do not exist on this
4909           platform, libpth is the cleaned-up version.
4910
4911       "gmake"
4912           From Loc.U:
4913
4914           This variable is used internally by Configure to determine the full
4915           pathname (if any) of the gmake program.  After Configure runs, the
4916           value is reset to a plain "gmake" and is not useful.
4917
4918       "gmtime_r_proto"
4919           From d_gmtime_r.U:
4920
4921           This variable encodes the prototype of gmtime_r.  It is zero if
4922           d_gmtime_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
4923           of reentr.h if d_gmtime_r is defined.
4924
4925       "gnulibc_version"
4926           From d_gnulibc.U:
4927
4928           This variable contains the version number of the "GNU" C library.
4929           It is usually something like 2.2.5.  It is a plain '' if this is
4930           not the "GNU" C library, or if the version is unknown.
4931
4932       "grep"
4933           From Loc.U:
4934
4935           This variable is used internally by Configure to determine the full
4936           pathname (if any) of the grep program.  After Configure runs, the
4937           value is reset to a plain "grep" and is not useful.
4938
4939       "groupcat"
4940           From nis.U:
4941
4942           This variable contains a command that produces the text of the
4943           /etc/group file.  This is normally "cat /etc/group", but can be
4944           "ypcat group" when "NIS" is used.  On some systems, such as os390,
4945           there may be no equivalent command, in which case this variable is
4946           unset.
4947
4948       "groupstype"
4949           From groupstype.U:
4950
4951           This variable defines Groups_t to be something like gid_t, int,
4952           ushort, or whatever type is used for the second argument to
4953           getgroups() and setgroups().  Usually, this is the same as gidtype
4954           (gid_t), but sometimes it isn't.
4955
4956       "gzip"
4957           From Loc.U:
4958
4959           This variable is used internally by Configure to determine the full
4960           pathname (if any) of the gzip program.  After Configure runs, the
4961           value is reset to a plain "gzip" and is not useful.
4962
4963   h
4964       "h_fcntl"
4965           From h_fcntl.U:
4966
4967           This is variable gets set in various places to tell i_fcntl that
4968           <fcntl.h> should be included.
4969
4970       "h_sysfile"
4971           From h_sysfile.U:
4972
4973           This is variable gets set in various places to tell i_sys_file that
4974           <sys/file.h> should be included.
4975
4976       "hint"
4977           From Oldconfig.U:
4978
4979           Gives the type of hints used for previous answers. May be one of
4980           "default", "recommended" or "previous".
4981
4982       "hostcat"
4983           From nis.U:
4984
4985           This variable contains a command that produces the text of the
4986           /etc/hosts file.  This is normally "cat /etc/hosts", but can be
4987           "ypcat hosts" when "NIS" is used.  On some systems, such as os390,
4988           there may be no equivalent command, in which case this variable is
4989           unset.
4990
4991       "hostgenerate"
4992           From Cross.U:
4993
4994           This variable contains the path to a generate_uudmap binary that
4995           can be run on the host "OS" when cross-compiling.  Useful and
4996           available only during Perl build.  Empty string '' if not cross-
4997           compiling.
4998
4999       "hostosname"
5000           From Cross.U:
5001
5002           This variable contains the original value of $^O for hostperl when
5003           cross-compiling.  This is useful to pick the proper tools when
5004           running build code in the host.  Empty string '' if not cross-
5005           compiling.
5006
5007       "hostperl"
5008           From Cross.U:
5009
5010           This variable contains the path to a miniperl binary that can be
5011           run on the host "OS" when cross-compiling.  Useful and available
5012           only during Perl build.  Empty string '' if not cross-compiling.
5013
5014       "html1dir"
5015           From html1dir.U:
5016
5017           This variable contains the name of the directory in which html
5018           source pages are to be put.  This directory is for pages that
5019           describe whole programs, not libraries or modules.  It is intended
5020           to correspond roughly to section 1 of the Unix manuals.
5021
5022       "html1direxp"
5023           From html1dir.U:
5024
5025           This variable is the same as the html1dir variable, but is filename
5026           expanded at configuration time, for convenient use in makefiles.
5027
5028       "html3dir"
5029           From html3dir.U:
5030
5031           This variable contains the name of the directory in which html
5032           source pages are to be put.  This directory is for pages that
5033           describe libraries or modules.  It is intended to correspond
5034           roughly to section 3 of the Unix manuals.
5035
5036       "html3direxp"
5037           From html3dir.U:
5038
5039           This variable is the same as the html3dir variable, but is filename
5040           expanded at configuration time, for convenient use in makefiles.
5041
5042   i
5043       "i16size"
5044           From perlxv.U:
5045
5046           This variable is the size of an I16 in bytes.
5047
5048       "i16type"
5049           From perlxv.U:
5050
5051           This variable contains the C type used for Perl's I16.
5052
5053       "i32size"
5054           From perlxv.U:
5055
5056           This variable is the size of an I32 in bytes.
5057
5058       "i32type"
5059           From perlxv.U:
5060
5061           This variable contains the C type used for Perl's I32.
5062
5063       "i64size"
5064           From perlxv.U:
5065
5066           This variable is the size of an I64 in bytes.
5067
5068       "i64type"
5069           From perlxv.U:
5070
5071           This variable contains the C type used for Perl's I64.
5072
5073       "i8size"
5074           From perlxv.U:
5075
5076           This variable is the size of an I8 in bytes.
5077
5078       "i8type"
5079           From perlxv.U:
5080
5081           This variable contains the C type used for Perl's I8.
5082
5083       "i_arpainet"
5084           From i_arpainet.U:
5085
5086           This variable conditionally defines the "I_ARPA_INET" symbol, and
5087           indicates whether a C program should include <arpa/inet.h>.
5088
5089       "i_bfd"
5090           From i_bfd.U:
5091
5092           This variable conditionally defines the "I_BFD" symbol, and
5093           indicates whether a C program can include <bfd.h>.
5094
5095       "i_bsdioctl"
5096           From i_sysioctl.U:
5097
5098           This variable conditionally defines the "I_SYS_BSDIOCTL" symbol,
5099           which indicates to the C program that <sys/bsdioctl.h> exists and
5100           should be included.
5101
5102       "i_crypt"
5103           From i_crypt.U:
5104
5105           This variable conditionally defines the "I_CRYPT" symbol, and
5106           indicates whether a C program should include <crypt.h>.
5107
5108       "i_db"
5109           From i_db.U:
5110
5111           This variable conditionally defines the "I_DB" symbol, and
5112           indicates whether a C program may include Berkeley's "DB" include
5113           file <db.h>.
5114
5115       "i_dbm"
5116           From i_dbm.U:
5117
5118           This variable conditionally defines the "I_DBM" symbol, which
5119           indicates to the C program that <dbm.h> exists and should be
5120           included.
5121
5122       "i_dirent"
5123           From i_dirent.U:
5124
5125           This variable conditionally defines "I_DIRENT", which indicates to
5126           the C program that it should include <dirent.h>.
5127
5128       "i_dlfcn"
5129           From i_dlfcn.U:
5130
5131           This variable conditionally defines the "I_DLFCN" symbol, which
5132           indicates to the C program that <dlfcn.h> exists and should be
5133           included.
5134
5135       "i_execinfo"
5136           From i_execinfo.U:
5137
5138           This variable conditionally defines the "I_EXECINFO" symbol, and
5139           indicates whether a C program may include <execinfo.h>, for
5140           backtrace() support.
5141
5142       "i_fcntl"
5143           From i_fcntl.U:
5144
5145           This variable controls the value of "I_FCNTL" (which tells the C
5146           program to include <fcntl.h>).
5147
5148       "i_fenv"
5149           From i_fenv.U:
5150
5151           This variable conditionally defines the "I_FENV" symbol, which
5152           indicates to the C program that <fenv.h> exists and should be
5153           included.
5154
5155       "i_fp"
5156           From i_fp.U:
5157
5158           This variable conditionally defines the "I_FP" symbol, and
5159           indicates whether a C program should include <fp.h>.
5160
5161       "i_fp_class"
5162           From i_fp_class.U:
5163
5164           This variable conditionally defines the "I_FP_CLASS" symbol, and
5165           indicates whether a C program should include <fp_class.h>.
5166
5167       "i_gdbm"
5168           From i_gdbm.U:
5169
5170           This variable conditionally defines the "I_GDBM" symbol, which
5171           indicates to the C program that <gdbm.h> exists and should be
5172           included.
5173
5174       "i_gdbm_ndbm"
5175           From i_ndbm.U:
5176
5177           This variable conditionally defines the "I_GDBM_NDBM" symbol, which
5178           indicates to the C program that <gdbm-ndbm.h> exists and should be
5179           included.  This is the location of the ndbm.h compatibility file in
5180           Debian 4.0.
5181
5182       "i_gdbmndbm"
5183           From i_ndbm.U:
5184
5185           This variable conditionally defines the "I_GDBMNDBM" symbol, which
5186           indicates to the C program that <gdbm/ndbm.h> exists and should be
5187           included.  This was the location of the ndbm.h compatibility file
5188           in RedHat 7.1.
5189
5190       "i_grp"
5191           From i_grp.U:
5192
5193           This variable conditionally defines the "I_GRP" symbol, and
5194           indicates whether a C program should include <grp.h>.
5195
5196       "i_ieeefp"
5197           From i_ieeefp.U:
5198
5199           This variable conditionally defines the "I_IEEEFP" symbol, and
5200           indicates whether a C program should include <ieeefp.h>.
5201
5202       "i_inttypes"
5203           From i_inttypes.U:
5204
5205           This variable conditionally defines the "I_INTTYPES" symbol, and
5206           indicates whether a C program should include <inttypes.h>.
5207
5208       "i_langinfo"
5209           From i_langinfo.U:
5210
5211           This variable conditionally defines the "I_LANGINFO" symbol, and
5212           indicates whether a C program should include <langinfo.h>.
5213
5214       "i_libutil"
5215           From i_libutil.U:
5216
5217           This variable conditionally defines the "I_LIBUTIL" symbol, and
5218           indicates whether a C program should include <libutil.h>.
5219
5220       "i_locale"
5221           From i_locale.U:
5222
5223           This variable conditionally defines the "I_LOCALE" symbol, and
5224           indicates whether a C program should include <locale.h>.
5225
5226       "i_machcthr"
5227           From i_machcthr.U:
5228
5229           This variable conditionally defines the "I_MACH_CTHREADS" symbol,
5230           and indicates whether a C program should include <mach/cthreads.h>.
5231
5232       "i_malloc"
5233           From i_malloc.U:
5234
5235           This variable conditionally defines the "I_MALLOC" symbol, and
5236           indicates whether a C program should include <malloc.h>.
5237
5238       "i_mallocmalloc"
5239           From i_mallocmalloc.U:
5240
5241           This variable conditionally defines the "I_MALLOCMALLOC" symbol,
5242           and indicates whether a C program should include <malloc/malloc.h>.
5243
5244       "i_mntent"
5245           From i_mntent.U:
5246
5247           This variable conditionally defines the "I_MNTENT" symbol, and
5248           indicates whether a C program should include <mntent.h>.
5249
5250       "i_ndbm"
5251           From i_ndbm.U:
5252
5253           This variable conditionally defines the "I_NDBM" symbol, which
5254           indicates to the C program that <ndbm.h> exists and should be
5255           included.
5256
5257       "i_netdb"
5258           From i_netdb.U:
5259
5260           This variable conditionally defines the "I_NETDB" symbol, and
5261           indicates whether a C program should include <netdb.h>.
5262
5263       "i_neterrno"
5264           From i_neterrno.U:
5265
5266           This variable conditionally defines the "I_NET_ERRNO" symbol, which
5267           indicates to the C program that <net/errno.h> exists and should be
5268           included.
5269
5270       "i_netinettcp"
5271           From i_netinettcp.U:
5272
5273           This variable conditionally defines the "I_NETINET_TCP" symbol, and
5274           indicates whether a C program should include <netinet/tcp.h>.
5275
5276       "i_niin"
5277           From i_niin.U:
5278
5279           This variable conditionally defines "I_NETINET_IN", which indicates
5280           to the C program that it should include <netinet/in.h>. Otherwise,
5281           you may try <sys/in.h>.
5282
5283       "i_poll"
5284           From i_poll.U:
5285
5286           This variable conditionally defines the "I_POLL" symbol, and
5287           indicates whether a C program should include <poll.h>.
5288
5289       "i_prot"
5290           From i_prot.U:
5291
5292           This variable conditionally defines the "I_PROT" symbol, and
5293           indicates whether a C program should include <prot.h>.
5294
5295       "i_pthread"
5296           From i_pthread.U:
5297
5298           This variable conditionally defines the "I_PTHREAD" symbol, and
5299           indicates whether a C program should include <pthread.h>.
5300
5301       "i_pwd"
5302           From i_pwd.U:
5303
5304           This variable conditionally defines "I_PWD", which indicates to the
5305           C program that it should include <pwd.h>.
5306
5307       "i_quadmath"
5308           From i_quadmath.U:
5309
5310           This variable conditionally defines "I_QUADMATH", which indicates
5311           to the C program that it should include <quadmath.h>.
5312
5313       "i_rpcsvcdbm"
5314           From i_dbm.U:
5315
5316           This variable conditionally defines the "I_RPCSVC_DBM" symbol,
5317           which indicates to the C program that <rpcsvc/dbm.h> exists and
5318           should be included.  Some System V systems might need this instead
5319           of <dbm.h>.
5320
5321       "i_sgtty"
5322           From i_termio.U:
5323
5324           This variable conditionally defines the "I_SGTTY" symbol, which
5325           indicates to the C program that it should include <sgtty.h> rather
5326           than <termio.h>.
5327
5328       "i_shadow"
5329           From i_shadow.U:
5330
5331           This variable conditionally defines the "I_SHADOW" symbol, and
5332           indicates whether a C program should include <shadow.h>.
5333
5334       "i_socks"
5335           From i_socks.U:
5336
5337           This variable conditionally defines the "I_SOCKS" symbol, and
5338           indicates whether a C program should include <socks.h>.
5339
5340       "i_stdbool"
5341           From i_stdbool.U:
5342
5343           This variable conditionally defines the "I_STDBOOL" symbol, which
5344           indicates to the C program that <stdbool.h> exists and should be
5345           included.
5346
5347       "i_stdint"
5348           From i_stdint.U:
5349
5350           This variable conditionally defines the "I_STDINT" symbol, which
5351           indicates to the C program that <stdint.h> exists and should be
5352           included.
5353
5354       "i_stdlib"
5355           From i_stdlib.U:
5356
5357           This variable unconditionally defines the "I_STDLIB" symbol.
5358
5359       "i_sunmath"
5360           From i_sunmath.U:
5361
5362           This variable conditionally defines the "I_SUNMATH" symbol, and
5363           indicates whether a C program should include <sunmath.h>.
5364
5365       "i_sysaccess"
5366           From i_sysaccess.U:
5367
5368           This variable conditionally defines the "I_SYS_ACCESS" symbol, and
5369           indicates whether a C program should include <sys/access.h>.
5370
5371       "i_sysdir"
5372           From i_sysdir.U:
5373
5374           This variable conditionally defines the "I_SYS_DIR" symbol, and
5375           indicates whether a C program should include <sys/dir.h>.
5376
5377       "i_sysfile"
5378           From i_sysfile.U:
5379
5380           This variable conditionally defines the "I_SYS_FILE" symbol, and
5381           indicates whether a C program should include <sys/file.h> to get
5382           "R_OK" and friends.
5383
5384       "i_sysfilio"
5385           From i_sysioctl.U:
5386
5387           This variable conditionally defines the "I_SYS_FILIO" symbol, which
5388           indicates to the C program that <sys/filio.h> exists and should be
5389           included in preference to <sys/ioctl.h>.
5390
5391       "i_sysin"
5392           From i_niin.U:
5393
5394           This variable conditionally defines "I_SYS_IN", which indicates to
5395           the C program that it should include <sys/in.h> instead of
5396           <netinet/in.h>.
5397
5398       "i_sysioctl"
5399           From i_sysioctl.U:
5400
5401           This variable conditionally defines the "I_SYS_IOCTL" symbol, which
5402           indicates to the C program that <sys/ioctl.h> exists and should be
5403           included.
5404
5405       "i_syslog"
5406           From i_syslog.U:
5407
5408           This variable conditionally defines the "I_SYSLOG" symbol, and
5409           indicates whether a C program should include <syslog.h>.
5410
5411       "i_sysmman"
5412           From i_sysmman.U:
5413
5414           This variable conditionally defines the "I_SYS_MMAN" symbol, and
5415           indicates whether a C program should include <sys/mman.h>.
5416
5417       "i_sysmode"
5418           From i_sysmode.U:
5419
5420           This variable conditionally defines the "I_SYSMODE" symbol, and
5421           indicates whether a C program should include <sys/mode.h>.
5422
5423       "i_sysmount"
5424           From i_sysmount.U:
5425
5426           This variable conditionally defines the "I_SYSMOUNT" symbol, and
5427           indicates whether a C program should include <sys/mount.h>.
5428
5429       "i_sysndir"
5430           From i_sysndir.U:
5431
5432           This variable conditionally defines the "I_SYS_NDIR" symbol, and
5433           indicates whether a C program should include <sys/ndir.h>.
5434
5435       "i_sysparam"
5436           From i_sysparam.U:
5437
5438           This variable conditionally defines the "I_SYS_PARAM" symbol, and
5439           indicates whether a C program should include <sys/param.h>.
5440
5441       "i_syspoll"
5442           From i_syspoll.U:
5443
5444           This variable conditionally defines the "I_SYS_POLL" symbol, which
5445           indicates to the C program that it should include <sys/poll.h>.
5446
5447       "i_sysresrc"
5448           From i_sysresrc.U:
5449
5450           This variable conditionally defines the "I_SYS_RESOURCE" symbol,
5451           and indicates whether a C program should include <sys/resource.h>.
5452
5453       "i_syssecrt"
5454           From i_syssecrt.U:
5455
5456           This variable conditionally defines the "I_SYS_SECURITY" symbol,
5457           and indicates whether a C program should include <sys/security.h>.
5458
5459       "i_sysselct"
5460           From i_sysselct.U:
5461
5462           This variable conditionally defines "I_SYS_SELECT", which indicates
5463           to the C program that it should include <sys/select.h> in order to
5464           get the definition of struct timeval.
5465
5466       "i_syssockio"
5467           From i_sysioctl.U:
5468
5469           This variable conditionally defines "I_SYS_SOCKIO" to indicate to
5470           the C program that socket ioctl codes may be found in
5471           <sys/sockio.h> instead of <sys/ioctl.h>.
5472
5473       "i_sysstat"
5474           From i_sysstat.U:
5475
5476           This variable conditionally defines the "I_SYS_STAT" symbol, and
5477           indicates whether a C program should include <sys/stat.h>.
5478
5479       "i_sysstatfs"
5480           From i_sysstatfs.U:
5481
5482           This variable conditionally defines the "I_SYSSTATFS" symbol, and
5483           indicates whether a C program should include <sys/statfs.h>.
5484
5485       "i_sysstatvfs"
5486           From i_sysstatvfs.U:
5487
5488           This variable conditionally defines the "I_SYSSTATVFS" symbol, and
5489           indicates whether a C program should include <sys/statvfs.h>.
5490
5491       "i_systime"
5492           From i_time.U:
5493
5494           This variable conditionally defines "I_SYS_TIME", which indicates
5495           to the C program that it should include <sys/time.h>.
5496
5497       "i_systimek"
5498           From i_time.U:
5499
5500           This variable conditionally defines "I_SYS_TIME_KERNEL", which
5501           indicates to the C program that it should include <sys/time.h> with
5502           "KERNEL" defined.
5503
5504       "i_systimes"
5505           From i_systimes.U:
5506
5507           This variable conditionally defines the "I_SYS_TIMES" symbol, and
5508           indicates whether a C program should include <sys/times.h>.
5509
5510       "i_systypes"
5511           From i_systypes.U:
5512
5513           This variable conditionally defines the "I_SYS_TYPES" symbol, and
5514           indicates whether a C program should include <sys/types.h>.
5515
5516       "i_sysuio"
5517           From i_sysuio.U:
5518
5519           This variable conditionally defines the "I_SYSUIO" symbol, and
5520           indicates whether a C program should include <sys/uio.h>.
5521
5522       "i_sysun"
5523           From i_sysun.U:
5524
5525           This variable conditionally defines "I_SYS_UN", which indicates to
5526           the C program that it should include <sys/un.h> to get "UNIX"
5527           domain socket definitions.
5528
5529       "i_sysutsname"
5530           From i_sysutsname.U:
5531
5532           This variable conditionally defines the "I_SYSUTSNAME" symbol, and
5533           indicates whether a C program should include <sys/utsname.h>.
5534
5535       "i_sysvfs"
5536           From i_sysvfs.U:
5537
5538           This variable conditionally defines the "I_SYSVFS" symbol, and
5539           indicates whether a C program should include <sys/vfs.h>.
5540
5541       "i_syswait"
5542           From i_syswait.U:
5543
5544           This variable conditionally defines "I_SYS_WAIT", which indicates
5545           to the C program that it should include <sys/wait.h>.
5546
5547       "i_termio"
5548           From i_termio.U:
5549
5550           This variable conditionally defines the "I_TERMIO" symbol, which
5551           indicates to the C program that it should include <termio.h> rather
5552           than <sgtty.h>.
5553
5554       "i_termios"
5555           From i_termio.U:
5556
5557           This variable conditionally defines the "I_TERMIOS" symbol, which
5558           indicates to the C program that the "POSIX" <termios.h> file is to
5559           be included.
5560
5561       "i_time"
5562           From i_time.U:
5563
5564           This variable unconditionally defines "I_TIME", which indicates to
5565           the C program that it should include <time.h>.
5566
5567       "i_unistd"
5568           From i_unistd.U:
5569
5570           This variable conditionally defines the "I_UNISTD" symbol, and
5571           indicates whether a C program should include <unistd.h>.
5572
5573       "i_ustat"
5574           From i_ustat.U:
5575
5576           This variable conditionally defines the "I_USTAT" symbol, and
5577           indicates whether a C program should include <ustat.h>.
5578
5579       "i_utime"
5580           From i_utime.U:
5581
5582           This variable conditionally defines the "I_UTIME" symbol, and
5583           indicates whether a C program should include <utime.h>.
5584
5585       "i_vfork"
5586           From i_vfork.U:
5587
5588           This variable conditionally defines the "I_VFORK" symbol, and
5589           indicates whether a C program should include vfork.h.
5590
5591       "i_wchar"
5592           From i_wchar.U:
5593
5594           This variable conditionally defines the "I_WCHAR" symbol, that
5595           indicates whether a C program may include <wchar.h>.
5596
5597       "i_wctype"
5598           From i_wctype.U:
5599
5600           This variable conditionally defines the "I_WCTYPE" symbol, that
5601           indicates whether a C program may include <wctype.h>.
5602
5603       "i_xlocale"
5604           From d_newlocale.U:
5605
5606           This symbol, if defined, indicates to the C program that it should
5607           include <xlocale.h> to get uselocale() and its friends
5608
5609       "ignore_versioned_solibs"
5610           From libs.U:
5611
5612           This variable should be non-empty if non-versioned shared libraries
5613           (libfoo.so.x.y) are to be ignored (because they cannot be linked
5614           against).
5615
5616       "inc_version_list"
5617           From inc_version_list.U:
5618
5619           This variable specifies the list of subdirectories in over which
5620           perl.c:incpush() and lib/lib.pm will automatically search when
5621           adding directories to @"INC".  The elements in the list are
5622           separated by spaces.  This is only useful if you have a perl
5623           library directory tree structured like the default one.  See
5624           "INSTALL" for how this works.  The versioned site_perl directory
5625           was introduced in 5.005, so that is the lowest possible value.
5626
5627           This list includes architecture-dependent directories back to
5628           version $api_versionstring (e.g. 5.5.640) and architecture-
5629           independent directories all the way back to 5.005.
5630
5631       "inc_version_list_init"
5632           From inc_version_list.U:
5633
5634           This variable holds the same list as inc_version_list, but each
5635           item is enclosed in double quotes and separated by commas, suitable
5636           for use in the "PERL_INC_VERSION_LIST" initialization.
5637
5638       "incpath"
5639           From usrinc.U:
5640
5641           This variable must precede the normal include path to get the right
5642           one, as in $incpath/usr/include or $incpath/usr/lib.  Value can be
5643           "" or /bsd43 on mips.
5644
5645       "incpth"
5646           From libpth.U:
5647
5648           This variable must precede the normal include path to get the right
5649           one, as in $incpath/usr/include or $incpath/usr/lib.  Value can be
5650           "" or /bsd43 on mips.
5651
5652       "inews"
5653           From Loc.U:
5654
5655           This variable is defined but not used by Configure.  The value is
5656           the empty string and is not useful.
5657
5658       "initialinstalllocation"
5659           From bin.U:
5660
5661           When userelocatableinc is true, this variable holds the location
5662           that make install should copy the perl binary to, with all the run-
5663           time relocatable paths calculated from this at install time.  When
5664           used, it is initialized to the original value of binexp, and then
5665           binexp is set to .../, as the other binaries are found relative to
5666           the perl binary.
5667
5668       "installarchlib"
5669           From archlib.U:
5670
5671           This variable is really the same as archlibexp but may differ on
5672           those systems using "AFS". For extra portability, only this
5673           variable should be used in makefiles.
5674
5675       "installbin"
5676           From bin.U:
5677
5678           This variable is the same as binexp unless "AFS" is running in
5679           which case the user is explicitly prompted for it. This variable
5680           should always be used in your makefiles for maximum portability.
5681
5682       "installhtml1dir"
5683           From html1dir.U:
5684
5685           This variable is really the same as html1direxp, unless you are
5686           using a different installprefix.  For extra portability, you should
5687           only use this variable within your makefiles.
5688
5689       "installhtml3dir"
5690           From html3dir.U:
5691
5692           This variable is really the same as html3direxp, unless you are
5693           using a different installprefix.  For extra portability, you should
5694           only use this variable within your makefiles.
5695
5696       "installman1dir"
5697           From man1dir.U:
5698
5699           This variable is really the same as man1direxp, unless you are
5700           using "AFS" in which case it points to the read/write location
5701           whereas man1direxp only points to the read-only access location.
5702           For extra portability, you should only use this variable within
5703           your makefiles.
5704
5705       "installman3dir"
5706           From man3dir.U:
5707
5708           This variable is really the same as man3direxp, unless you are
5709           using "AFS" in which case it points to the read/write location
5710           whereas man3direxp only points to the read-only access location.
5711           For extra portability, you should only use this variable within
5712           your makefiles.
5713
5714       "installprefix"
5715           From installprefix.U:
5716
5717           This variable holds the name of the directory below which "make
5718           install" will install the package.  For most users, this is the
5719           same as prefix.  However, it is useful for installing the software
5720           into a different (usually temporary) location after which it can be
5721           bundled up and moved somehow to the final location specified by
5722           prefix.
5723
5724       "installprefixexp"
5725           From installprefix.U:
5726
5727           This variable holds the full absolute path of installprefix with
5728           all ~-expansion done.
5729
5730       "installprivlib"
5731           From privlib.U:
5732
5733           This variable is really the same as privlibexp but may differ on
5734           those systems using "AFS". For extra portability, only this
5735           variable should be used in makefiles.
5736
5737       "installscript"
5738           From scriptdir.U:
5739
5740           This variable is usually the same as scriptdirexp, unless you are
5741           on a system running "AFS", in which case they may differ slightly.
5742           You should always use this variable within your makefiles for
5743           portability.
5744
5745       "installsitearch"
5746           From sitearch.U:
5747
5748           This variable is really the same as sitearchexp but may differ on
5749           those systems using "AFS". For extra portability, only this
5750           variable should be used in makefiles.
5751
5752       "installsitebin"
5753           From sitebin.U:
5754
5755           This variable is usually the same as sitebinexp, unless you are on
5756           a system running "AFS", in which case they may differ slightly. You
5757           should always use this variable within your makefiles for
5758           portability.
5759
5760       "installsitehtml1dir"
5761           From sitehtml1dir.U:
5762
5763           This variable is really the same as sitehtml1direxp, unless you are
5764           using "AFS" in which case it points to the read/write location
5765           whereas html1direxp only points to the read-only access location.
5766           For extra portability, you should only use this variable within
5767           your makefiles.
5768
5769       "installsitehtml3dir"
5770           From sitehtml3dir.U:
5771
5772           This variable is really the same as sitehtml3direxp, unless you are
5773           using "AFS" in which case it points to the read/write location
5774           whereas html3direxp only points to the read-only access location.
5775           For extra portability, you should only use this variable within
5776           your makefiles.
5777
5778       "installsitelib"
5779           From sitelib.U:
5780
5781           This variable is really the same as sitelibexp but may differ on
5782           those systems using "AFS". For extra portability, only this
5783           variable should be used in makefiles.
5784
5785       "installsiteman1dir"
5786           From siteman1dir.U:
5787
5788           This variable is really the same as siteman1direxp, unless you are
5789           using "AFS" in which case it points to the read/write location
5790           whereas man1direxp only points to the read-only access location.
5791           For extra portability, you should only use this variable within
5792           your makefiles.
5793
5794       "installsiteman3dir"
5795           From siteman3dir.U:
5796
5797           This variable is really the same as siteman3direxp, unless you are
5798           using "AFS" in which case it points to the read/write location
5799           whereas man3direxp only points to the read-only access location.
5800           For extra portability, you should only use this variable within
5801           your makefiles.
5802
5803       "installsitescript"
5804           From sitescript.U:
5805
5806           This variable is usually the same as sitescriptexp, unless you are
5807           on a system running "AFS", in which case they may differ slightly.
5808           You should always use this variable within your makefiles for
5809           portability.
5810
5811       "installstyle"
5812           From installstyle.U:
5813
5814           This variable describes the "style" of the perl installation.  This
5815           is intended to be useful for tools that need to manipulate entire
5816           perl distributions.  Perl itself doesn't use this to find its
5817           libraries -- the library directories are stored directly in
5818           Config.pm.  Currently, there are only two styles:  "lib" and
5819           lib/perl5.  The default library locations (e.g. privlib, sitelib)
5820           are either $prefix/lib or $prefix/lib/perl5.  The former is useful
5821           if $prefix is a directory dedicated to perl (e.g. /opt/perl), while
5822           the latter is useful if $prefix is shared by many packages, e.g. if
5823           $prefix=/usr/local.
5824
5825           Unfortunately, while this "style" variable is used to set defaults
5826           for all three directory hierarchies (core, vendor, and site), there
5827           is no guarantee that the same style is actually appropriate for all
5828           those directories.  For example, $prefix might be /opt/perl, but
5829           $siteprefix might be /usr/local.  (Perhaps, in retrospect, the
5830           "lib" style should never have been supported, but it did seem like
5831           a nice idea at the time.)
5832
5833           The situation is even less clear for tools such as MakeMaker that
5834           can be used to install additional modules into non-standard places.
5835           For example, if a user intends to install a module into a private
5836           directory (perhaps by setting "PREFIX" on the Makefile.PL command
5837           line), then there is no reason to assume that the Configure-time
5838           $installstyle setting will be relevant for that "PREFIX".
5839
5840           This may later be extended to include other information, so be
5841           careful with pattern-matching on the results.
5842
5843           For compatibility with perl5.005 and earlier, the default setting
5844           is based on whether or not $prefix contains the string "perl".
5845
5846       "installusrbinperl"
5847           From instubperl.U:
5848
5849           This variable tells whether Perl should be installed also as
5850           /usr/bin/perl in addition to $installbin/perl
5851
5852       "installvendorarch"
5853           From vendorarch.U:
5854
5855           This variable is really the same as vendorarchexp but may differ on
5856           those systems using "AFS". For extra portability, only this
5857           variable should be used in makefiles.
5858
5859       "installvendorbin"
5860           From vendorbin.U:
5861
5862           This variable is really the same as vendorbinexp but may differ on
5863           those systems using "AFS". For extra portability, only this
5864           variable should be used in makefiles.
5865
5866       "installvendorhtml1dir"
5867           From vendorhtml1dir.U:
5868
5869           This variable is really the same as vendorhtml1direxp but may
5870           differ on those systems using "AFS". For extra portability, only
5871           this variable should be used in makefiles.
5872
5873       "installvendorhtml3dir"
5874           From vendorhtml3dir.U:
5875
5876           This variable is really the same as vendorhtml3direxp but may
5877           differ on those systems using "AFS". For extra portability, only
5878           this variable should be used in makefiles.
5879
5880       "installvendorlib"
5881           From vendorlib.U:
5882
5883           This variable is really the same as vendorlibexp but may differ on
5884           those systems using "AFS". For extra portability, only this
5885           variable should be used in makefiles.
5886
5887       "installvendorman1dir"
5888           From vendorman1dir.U:
5889
5890           This variable is really the same as vendorman1direxp but may differ
5891           on those systems using "AFS". For extra portability, only this
5892           variable should be used in makefiles.
5893
5894       "installvendorman3dir"
5895           From vendorman3dir.U:
5896
5897           This variable is really the same as vendorman3direxp but may differ
5898           on those systems using "AFS". For extra portability, only this
5899           variable should be used in makefiles.
5900
5901       "installvendorscript"
5902           From vendorscript.U:
5903
5904           This variable is really the same as vendorscriptexp but may differ
5905           on those systems using "AFS". For extra portability, only this
5906           variable should be used in makefiles.
5907
5908       "intsize"
5909           From intsize.U:
5910
5911           This variable contains the value of the "INTSIZE" symbol, which
5912           indicates to the C program how many bytes there are in an int.
5913
5914       "issymlink"
5915           From issymlink.U:
5916
5917           This variable holds the test command to test for a symbolic link
5918           (if they are supported).  Typical values include "test -h" and
5919           "test -L".
5920
5921       "ivdformat"
5922           From perlxvf.U:
5923
5924           This variable contains the format string used for printing a Perl
5925           "IV" as a signed decimal integer.
5926
5927       "ivsize"
5928           From perlxv.U:
5929
5930           This variable is the size of an "IV" in bytes.
5931
5932       "ivtype"
5933           From perlxv.U:
5934
5935           This variable contains the C type used for Perl's "IV".
5936
5937   k
5938       "known_extensions"
5939           From Extensions.U:
5940
5941           This variable holds a list of all extensions (both "XS" and non-xs)
5942           included in the package source distribution.  This information is
5943           only really of use during the Perl build, as the list makes no
5944           distinction between extensions which were build and installed, and
5945           those which where not.  See "extensions" for the list of extensions
5946           actually built and available.
5947
5948       "ksh"
5949           From Loc.U:
5950
5951           This variable is defined but not used by Configure.  The value is
5952           the empty string and is not useful.
5953
5954   l
5955       "ld"
5956           From dlsrc.U:
5957
5958           This variable indicates the program to be used to link libraries
5959           for dynamic loading.  On some systems, it is "ld".  On "ELF"
5960           systems, it should be $cc.  Mostly, we'll try to respect the hint
5961           file setting.
5962
5963       "ld_can_script"
5964           From dlsrc.U:
5965
5966           This variable shows if the loader accepts scripts in the form of
5967           -Wl,--version-script=ld.script. This is currently only supported
5968           for "GNU" ld on "ELF" in dynamic loading builds.
5969
5970       "lddlflags"
5971           From dlsrc.U:
5972
5973           This variable contains any special flags that might need to be
5974           passed to $ld to create a shared library suitable for dynamic
5975           loading.  It is up to the makefile to use it.  For hpux, it should
5976           be "-b".  For sunos 4.1, it is empty.
5977
5978       "ldflags"
5979           From ccflags.U:
5980
5981           This variable contains any additional C loader flags desired by the
5982           user.  It is up to the Makefile to use this.
5983
5984       "ldflags_uselargefiles"
5985           From uselfs.U:
5986
5987           This variable contains the loader flags needed by large file builds
5988           and added to ldflags by hints files.
5989
5990       "ldlibpthname"
5991           From libperl.U:
5992
5993           This variable holds the name of the shared library search path,
5994           often "LD_LIBRARY_PATH".  To get an empty string, the hints file
5995           must set this to "none".
5996
5997       "less"
5998           From Loc.U:
5999
6000           This variable is used internally by Configure to determine the full
6001           pathname (if any) of the less program.  After Configure runs, the
6002           value is reset to a plain "less" and is not useful.
6003
6004       "lib_ext"
6005           From Unix.U:
6006
6007           This is an old synonym for _a.
6008
6009       "libc"
6010           From libc.U:
6011
6012           This variable contains the location of the C library.
6013
6014       "libperl"
6015           From libperl.U:
6016
6017           The perl executable is obtained by linking perlmain.c with libperl,
6018           any static extensions (usually just DynaLoader), and any other
6019           libraries needed on this system.  libperl is usually libperl.a, but
6020           can also be libperl.so.xxx if the user wishes to build a perl
6021           executable with a shared library.
6022
6023       "libpth"
6024           From libpth.U:
6025
6026           This variable holds the general path (space-separated) used to find
6027           libraries. It is intended to be used by other units.
6028
6029       "libs"
6030           From libs.U:
6031
6032           This variable holds the additional libraries we want to use.  It is
6033           up to the Makefile to deal with it.  The list can be empty.
6034
6035       "libsdirs"
6036           From libs.U:
6037
6038           This variable holds the directory names aka dirnames of the
6039           libraries we found and accepted, duplicates are removed.
6040
6041       "libsfiles"
6042           From libs.U:
6043
6044           This variable holds the filenames aka basenames of the libraries we
6045           found and accepted.
6046
6047       "libsfound"
6048           From libs.U:
6049
6050           This variable holds the full pathnames of the libraries we found
6051           and accepted.
6052
6053       "libspath"
6054           From libs.U:
6055
6056           This variable holds the directory names probed for libraries.
6057
6058       "libswanted"
6059           From Myinit.U:
6060
6061           This variable holds a list of all the libraries we want to search.
6062           The order is chosen to pick up the c library ahead of ucb or bsd
6063           libraries for SVR4.
6064
6065       "libswanted_uselargefiles"
6066           From uselfs.U:
6067
6068           This variable contains the libraries needed by large file builds
6069           and added to ldflags by hints files.  It is a space separated list
6070           of the library names without the "lib" prefix or any suffix, just
6071           like libswanted..
6072
6073       "line"
6074           From Loc.U:
6075
6076           This variable is defined but not used by Configure.  The value is
6077           the empty string and is not useful.
6078
6079       "lint"
6080           From Loc.U:
6081
6082           This variable is defined but not used by Configure.  The value is
6083           the empty string and is not useful.
6084
6085       "lkflags"
6086           From ccflags.U:
6087
6088           This variable contains any additional C partial linker flags
6089           desired by the user.  It is up to the Makefile to use this.
6090
6091       "ln"
6092           From Loc.U:
6093
6094           This variable is used internally by Configure to determine the full
6095           pathname (if any) of the ln program.  After Configure runs, the
6096           value is reset to a plain "ln" and is not useful.
6097
6098       "lns"
6099           From lns.U:
6100
6101           This variable holds the name of the command to make symbolic links
6102           (if they are supported).  It can be used in the Makefile. It is
6103           either "ln -s" or "ln"
6104
6105       "localtime_r_proto"
6106           From d_localtime_r.U:
6107
6108           This variable encodes the prototype of localtime_r.  It is zero if
6109           d_localtime_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
6110           macros of reentr.h if d_localtime_r is defined.
6111
6112       "locincpth"
6113           From ccflags.U:
6114
6115           This variable contains a list of additional directories to be
6116           searched by the compiler.  The appropriate "-I" directives will be
6117           added to ccflags.  This is intended to simplify setting local
6118           directories from the Configure command line.  It's not much, but it
6119           parallels the loclibpth stuff in libpth.U.
6120
6121       "loclibpth"
6122           From libpth.U:
6123
6124           This variable holds the paths (space-separated) used to find local
6125           libraries.  It is prepended to libpth, and is intended to be easily
6126           set from the command line.
6127
6128       "longdblinfbytes"
6129           From infnan.U:
6130
6131           This variable contains comma-separated list of hexadecimal bytes
6132           for the long double precision infinity.
6133
6134       "longdblkind"
6135           From d_longdbl.U:
6136
6137           This variable, if defined, encodes the type of a long double: 0 =
6138           double, 1 = "IEEE" 754 128-bit little endian, 2 = "IEEE" 754
6139           128-bit big endian, 3 = x86 80-bit little endian, 4 = x86 80-bit
6140           big endian, 5 = double-double 128-bit little endian, 6 = double-
6141           double 128-bit big endian, 7 = 128-bit mixed-endian double-double
6142           (64-bit LEs in "BE"), 8 = 128-bit mixed-endian double-double
6143           (64-bit BEs in "LE"), 9 = 128-bit "PDP"-style mixed-endian long
6144           doubles, -1 = unknown format.
6145
6146       "longdblmantbits"
6147           From mantbits.U:
6148
6149           This symbol, if defined, tells how many mantissa bits there are in
6150           long double precision floating point format.  Note that this can be
6151           "LDBL_MANT_DIG" minus one, since "LDBL_MANT_DIG" can include the
6152           "IEEE" 754 implicit bit.  The common x86-style 80-bit long double
6153           does not have an implicit bit.
6154
6155       "longdblnanbytes"
6156           From infnan.U:
6157
6158           This variable contains comma-separated list of hexadecimal bytes
6159           for the long double precision not-a-number.
6160
6161       "longdblsize"
6162           From d_longdbl.U:
6163
6164           This variable contains the value of the "LONG_DOUBLESIZE" symbol,
6165           which indicates to the C program how many bytes there are in a long
6166           double, if this system supports long doubles.  Note that this is
6167           sizeof(long double), which may include unused bytes.
6168
6169       "longlongsize"
6170           From d_longlong.U:
6171
6172           This variable contains the value of the "LONGLONGSIZE" symbol,
6173           which indicates to the C program how many bytes there are in a long
6174           long, if this system supports long long.
6175
6176       "longsize"
6177           From intsize.U:
6178
6179           This variable contains the value of the "LONGSIZE" symbol, which
6180           indicates to the C program how many bytes there are in a long.
6181
6182       "lp"
6183           From Loc.U:
6184
6185           This variable is defined but not used by Configure.  The value is
6186           the empty string and is not useful.
6187
6188       "lpr"
6189           From Loc.U:
6190
6191           This variable is defined but not used by Configure.  The value is
6192           the empty string and is not useful.
6193
6194       "ls"
6195           From Loc.U:
6196
6197           This variable is used internally by Configure to determine the full
6198           pathname (if any) of the ls program.  After Configure runs, the
6199           value is reset to a plain "ls" and is not useful.
6200
6201       "lseeksize"
6202           From lseektype.U:
6203
6204           This variable defines lseektype to be something like off_t, long,
6205           or whatever type is used to declare lseek offset's type in the
6206           kernel (which also appears to be lseek's return type).
6207
6208       "lseektype"
6209           From lseektype.U:
6210
6211           This variable defines lseektype to be something like off_t, long,
6212           or whatever type is used to declare lseek offset's type in the
6213           kernel (which also appears to be lseek's return type).
6214
6215   m
6216       "mail"
6217           From Loc.U:
6218
6219           This variable is defined but not used by Configure.  The value is
6220           the empty string and is not useful.
6221
6222       "mailx"
6223           From Loc.U:
6224
6225           This variable is defined but not used by Configure.  The value is
6226           the empty string and is not useful.
6227
6228       "make"
6229           From Loc.U:
6230
6231           This variable is used internally by Configure to determine the full
6232           pathname (if any) of the make program.  After Configure runs, the
6233           value is reset to a plain "make" and is not useful.
6234
6235       "make_set_make"
6236           From make.U:
6237
6238           Some versions of "make" set the variable "MAKE".  Others do not.
6239           This variable contains the string to be included in Makefile.SH so
6240           that "MAKE" is set if needed, and not if not needed.  Possible
6241           values are:
6242
6243           make_set_make="#"        # If your make program handles this for
6244           you,
6245
6246           make_set_make="MAKE=$make"    # if it doesn't.
6247
6248           This uses a comment character so that we can distinguish a "set"
6249           value (from a previous config.sh or Configure "-D" option) from an
6250           uncomputed value.
6251
6252       "mallocobj"
6253           From mallocsrc.U:
6254
6255           This variable contains the name of the malloc.o that this package
6256           generates, if that malloc.o is preferred over the system malloc.
6257           Otherwise the value is null.  This variable is intended for
6258           generating Makefiles.  See mallocsrc.
6259
6260       "mallocsrc"
6261           From mallocsrc.U:
6262
6263           This variable contains the name of the malloc.c that comes with the
6264           package, if that malloc.c is preferred over the system malloc.
6265           Otherwise the value is null.  This variable is intended for
6266           generating Makefiles.
6267
6268       "malloctype"
6269           From mallocsrc.U:
6270
6271           This variable contains the kind of ptr returned by malloc and
6272           realloc.
6273
6274       "man1dir"
6275           From man1dir.U:
6276
6277           This variable contains the name of the directory in which manual
6278           source pages are to be put.  It is the responsibility of the
6279           Makefile.SH to get the value of this into the proper command.  You
6280           must be prepared to do the ~name expansion yourself.
6281
6282       "man1direxp"
6283           From man1dir.U:
6284
6285           This variable is the same as the man1dir variable, but is filename
6286           expanded at configuration time, for convenient use in makefiles.
6287
6288       "man1ext"
6289           From man1dir.U:
6290
6291           This variable contains the extension that the manual page should
6292           have: one of "n", "l", or 1.  The Makefile must supply the ..  See
6293           man1dir.
6294
6295       "man3dir"
6296           From man3dir.U:
6297
6298           This variable contains the name of the directory in which manual
6299           source pages are to be put.  It is the responsibility of the
6300           Makefile.SH to get the value of this into the proper command.  You
6301           must be prepared to do the ~name expansion yourself.
6302
6303       "man3direxp"
6304           From man3dir.U:
6305
6306           This variable is the same as the man3dir variable, but is filename
6307           expanded at configuration time, for convenient use in makefiles.
6308
6309       "man3ext"
6310           From man3dir.U:
6311
6312           This variable contains the extension that the manual page should
6313           have: one of "n", "l", or 3.  The Makefile must supply the ..  See
6314           man3dir.
6315
6316       "mips_type"
6317           From usrinc.U:
6318
6319           This variable holds the environment type for the mips system.
6320           Possible values are "BSD 4.3" and "System V".
6321
6322       "mistrustnm"
6323           From Csym.U:
6324
6325           This variable can be used to establish a fallthrough for the cases
6326           where nm fails to find a symbol.  If usenm is false or usenm is
6327           true and mistrustnm is false, this variable has no effect.  If
6328           usenm is true and mistrustnm is "compile", a test program will be
6329           compiled to try to find any symbol that can't be located via nm
6330           lookup.  If mistrustnm is "run", the test program will be run as
6331           well as being compiled.
6332
6333       "mkdir"
6334           From Loc.U:
6335
6336           This variable is used internally by Configure to determine the full
6337           pathname (if any) of the mkdir program.  After Configure runs, the
6338           value is reset to a plain "mkdir" and is not useful.
6339
6340       "mmaptype"
6341           From d_mmap.U:
6342
6343           This symbol contains the type of pointer returned by mmap() (and
6344           simultaneously the type of the first argument).  It can be "void *"
6345           or "caddr_t".
6346
6347       "modetype"
6348           From modetype.U:
6349
6350           This variable defines modetype to be something like mode_t, int,
6351           unsigned short, or whatever type is used to declare file modes for
6352           system calls.
6353
6354       "more"
6355           From Loc.U:
6356
6357           This variable is used internally by Configure to determine the full
6358           pathname (if any) of the more program.  After Configure runs, the
6359           value is reset to a plain "more" and is not useful.
6360
6361       "multiarch"
6362           From multiarch.U:
6363
6364           This variable conditionally defines the "MULTIARCH" symbol which
6365           signifies the presence of multiplatform files.  This is normally
6366           set by hints files.
6367
6368       "mv"
6369           From Loc.U:
6370
6371           This variable is defined but not used by Configure.  The value is
6372           the empty string and is not useful.
6373
6374       "myarchname"
6375           From archname.U:
6376
6377           This variable holds the architecture name computed by Configure in
6378           a previous run. It is not intended to be perused by any user and
6379           should never be set in a hint file.
6380
6381       "mydomain"
6382           From myhostname.U:
6383
6384           This variable contains the eventual value of the "MYDOMAIN" symbol,
6385           which is the domain of the host the program is going to run on.
6386           The domain must be appended to myhostname to form a complete host
6387           name.  The dot comes with mydomain, and need not be supplied by the
6388           program.
6389
6390       "myhostname"
6391           From myhostname.U:
6392
6393           This variable contains the eventual value of the "MYHOSTNAME"
6394           symbol, which is the name of the host the program is going to run
6395           on.  The domain is not kept with hostname, but must be gotten from
6396           mydomain.  The dot comes with mydomain, and need not be supplied by
6397           the program.
6398
6399       "myuname"
6400           From Oldconfig.U:
6401
6402           The output of "uname -a" if available, otherwise the hostname.  The
6403           whole thing is then lower-cased and slashes and single quotes are
6404           removed.
6405
6406   n
6407       "n" From n.U:
6408
6409           This variable contains the "-n" flag if that is what causes the
6410           echo command to suppress newline.  Otherwise it is null.  Correct
6411           usage is $echo $n "prompt for a question: $c".
6412
6413       "need_va_copy"
6414           From need_va_copy.U:
6415
6416           This symbol, if defined, indicates that the system stores the
6417           variable argument list datatype, va_list, in a format that cannot
6418           be copied by simple assignment, so that some other means must be
6419           used when copying is required.  As such systems vary in their
6420           provision (or non-provision) of copying mechanisms, handy.h defines
6421           a platform- "independent" macro, Perl_va_copy(src, dst), to do the
6422           job.
6423
6424       "netdb_hlen_type"
6425           From netdbtype.U:
6426
6427           This variable holds the type used for the 2nd argument to
6428           gethostbyaddr().  Usually, this is int or size_t or unsigned.  This
6429           is only useful if you have gethostbyaddr(), naturally.
6430
6431       "netdb_host_type"
6432           From netdbtype.U:
6433
6434           This variable holds the type used for the 1st argument to
6435           gethostbyaddr().  Usually, this is char * or void *,  possibly with
6436           or without a const prefix.  This is only useful if you have
6437           gethostbyaddr(), naturally.
6438
6439       "netdb_name_type"
6440           From netdbtype.U:
6441
6442           This variable holds the type used for the argument to
6443           gethostbyname().  Usually, this is char * or const char *.  This is
6444           only useful if you have gethostbyname(), naturally.
6445
6446       "netdb_net_type"
6447           From netdbtype.U:
6448
6449           This variable holds the type used for the 1st argument to
6450           getnetbyaddr().  Usually, this is int or long.  This is only useful
6451           if you have getnetbyaddr(), naturally.
6452
6453       "nm"
6454           From Loc.U:
6455
6456           This variable is used internally by Configure to determine the full
6457           pathname (if any) of the nm program.  After Configure runs, the
6458           value is reset to a plain "nm" and is not useful.
6459
6460       "nm_opt"
6461           From usenm.U:
6462
6463           This variable holds the options that may be necessary for nm.
6464
6465       "nm_so_opt"
6466           From usenm.U:
6467
6468           This variable holds the options that may be necessary for nm to
6469           work on a shared library but that can not be used on an archive
6470           library.  Currently, this is only used by Linux, where nm --dynamic
6471           is *required* to get symbols from an "ELF" library which has been
6472           stripped, but nm --dynamic is *fatal* on an archive library.  Maybe
6473           Linux should just always set usenm=false.
6474
6475       "nonxs_ext"
6476           From Extensions.U:
6477
6478           This variable holds a list of all non-xs extensions built and
6479           installed by the package.  By default, all non-xs extensions
6480           distributed will be built, with the exception of platform-specific
6481           extensions (currently only one "VMS" specific extension).
6482
6483       "nroff"
6484           From Loc.U:
6485
6486           This variable is used internally by Configure to determine the full
6487           pathname (if any) of the nroff program.  After Configure runs, the
6488           value is reset to a plain "nroff" and is not useful.
6489
6490       "nv_overflows_integers_at"
6491           From perlxv.U:
6492
6493           This variable gives the largest integer value that NVs can hold as
6494           a constant floating point expression.  If it could not be
6495           determined, it holds the value 0.
6496
6497       "nv_preserves_uv_bits"
6498           From perlxv.U:
6499
6500           This variable indicates how many of bits type uvtype a variable
6501           nvtype can preserve.
6502
6503       "nveformat"
6504           From perlxvf.U:
6505
6506           This variable contains the format string used for printing a Perl
6507           "NV" using %e-ish floating point format.
6508
6509       "nvEUformat"
6510           From perlxvf.U:
6511
6512           This variable contains the format string used for printing a Perl
6513           "NV" using %E-ish floating point format.
6514
6515       "nvfformat"
6516           From perlxvf.U:
6517
6518           This variable contains the format string used for printing a Perl
6519           "NV" using %f-ish floating point format.
6520
6521       "nvFUformat"
6522           From perlxvf.U:
6523
6524           This variable contains the format string used for printing a Perl
6525           "NV" using %F-ish floating point format.
6526
6527       "nvgformat"
6528           From perlxvf.U:
6529
6530           This variable contains the format string used for printing a Perl
6531           "NV" using %g-ish floating point format.
6532
6533       "nvGUformat"
6534           From perlxvf.U:
6535
6536           This variable contains the format string used for printing a Perl
6537           "NV" using %G-ish floating point format.
6538
6539       "nvmantbits"
6540           From mantbits.U:
6541
6542           This variable tells how many bits the mantissa of a Perl "NV" has,
6543           not including the possible implicit bit.
6544
6545       "nvsize"
6546           From perlxv.U:
6547
6548           This variable is the size of a Perl "NV" in bytes.  Note that some
6549           floating point formats have unused bytes.
6550
6551       "nvtype"
6552           From perlxv.U:
6553
6554           This variable contains the C type used for Perl's "NV".
6555
6556   o
6557       "o_nonblock"
6558           From nblock_io.U:
6559
6560           This variable bears the symbol value to be used during open() or
6561           fcntl() to turn on non-blocking I/O for a file descriptor. If you
6562           wish to switch between blocking and non-blocking, you may try
6563           ioctl("FIOSNBIO") instead, but that is only supported by some
6564           devices.
6565
6566       "obj_ext"
6567           From Unix.U:
6568
6569           This is an old synonym for _o.
6570
6571       "old_pthread_create_joinable"
6572           From d_pthrattrj.U:
6573
6574           This variable defines the constant to use for creating joinable
6575           (aka undetached) pthreads.  Unused if pthread.h defines
6576           "PTHREAD_CREATE_JOINABLE".  If used, possible values are
6577           "PTHREAD_CREATE_UNDETACHED" and "__UNDETACHED".
6578
6579       "optimize"
6580           From ccflags.U:
6581
6582           This variable contains any optimizer/debugger flag that should be
6583           used.  It is up to the Makefile to use it.
6584
6585       "orderlib"
6586           From orderlib.U:
6587
6588           This variable is "true" if the components of libraries must be
6589           ordered (with `lorder $* | tsort`) before placing them in an
6590           archive.  Set to "false" if ranlib or ar can generate random
6591           libraries.
6592
6593       "osname"
6594           From Oldconfig.U:
6595
6596           This variable contains the operating system name (e.g. sunos,
6597           solaris, hpux, etc.).  It can be useful later on for setting
6598           defaults.  Any spaces are replaced with underscores.  It is set to
6599           a null string if we can't figure it out.
6600
6601       "osvers"
6602           From Oldconfig.U:
6603
6604           This variable contains the operating system version (e.g.  4.1.3,
6605           5.2, etc.).  It is primarily used for helping select an appropriate
6606           hints file, but might be useful elsewhere for setting defaults.  It
6607           is set to '' if we can't figure it out.  We try to be flexible
6608           about how much of the version number to keep, e.g. if 4.1.1, 4.1.2,
6609           and 4.1.3 are essentially the same for this package, hints files
6610           might just be os_4.0 or os_4.1, etc., not keeping separate files
6611           for each little release.
6612
6613       "otherlibdirs"
6614           From otherlibdirs.U:
6615
6616           This variable contains a colon-separated set of paths for the perl
6617           binary to search for additional library files or modules.  These
6618           directories will be tacked to the end of @"INC".  Perl will
6619           automatically search below each path for version- and architecture-
6620           specific directories.  See inc_version_list for more details.  A
6621           value of " " means "none" and is used to preserve this value for
6622           the next run through Configure.
6623
6624   p
6625       "package"
6626           From package.U:
6627
6628           This variable contains the name of the package being constructed.
6629           It is primarily intended for the use of later Configure units.
6630
6631       "pager"
6632           From pager.U:
6633
6634           This variable contains the name of the preferred pager on the
6635           system.  Usual values are (the full pathnames of) more, less, pg,
6636           or cat.
6637
6638       "passcat"
6639           From nis.U:
6640
6641           This variable contains a command that produces the text of the
6642           /etc/passwd file.  This is normally "cat /etc/passwd", but can be
6643           "ypcat passwd" when "NIS" is used.  On some systems, such as os390,
6644           there may be no equivalent command, in which case this variable is
6645           unset.
6646
6647       "patchlevel"
6648           From patchlevel.U:
6649
6650           The patchlevel level of this package.  The value of patchlevel
6651           comes from the patchlevel.h file.  In a version number such as
6652           5.6.1, this is the 6.  In patchlevel.h, this is referred to as
6653           "PERL_VERSION".
6654
6655       "path_sep"
6656           From Unix.U:
6657
6658           This is an old synonym for p_ in Head.U, the character used to
6659           separate elements in the command shell search "PATH".
6660
6661       "perl"
6662           From Loc.U:
6663
6664           This variable is used internally by Configure to determine the full
6665           pathname (if any) of the perl program.  After Configure runs, the
6666           value is reset to a plain "perl" and is not useful.
6667
6668       "perl5"
6669           From perl5.U:
6670
6671           This variable contains the full path (if any) to a previously
6672           installed perl5.005 or later suitable for running the script to
6673           determine inc_version_list.
6674
6675   P
6676       "PERL_API_REVISION"
6677           From patchlevel.h:
6678
6679           This number describes the earliest compatible "PERL_REVISION" of
6680           Perl ("compatibility" here being defined as sufficient binary/"API"
6681           compatibility to run "XS" code built with the older version).
6682           Normally this does not change across maintenance releases.  Please
6683           read the comment in patchlevel.h.
6684
6685       "PERL_API_SUBVERSION"
6686           From patchlevel.h:
6687
6688           This number describes the earliest compatible "PERL_SUBVERSION" of
6689           Perl ("compatibility" here being defined as sufficient binary/"API"
6690           compatibility to run "XS" code built with the older version).
6691           Normally this does not change across maintenance releases.  Please
6692           read the comment in patchlevel.h.
6693
6694       "PERL_API_VERSION"
6695           From patchlevel.h:
6696
6697           This number describes the earliest compatible "PERL_VERSION" of
6698           Perl ("compatibility" here being defined as sufficient binary/"API"
6699           compatibility to run "XS" code built with the older version).
6700           Normally this does not change across maintenance releases.  Please
6701           read the comment in patchlevel.h.
6702
6703       "PERL_CONFIG_SH"
6704           From Oldsyms.U:
6705
6706           This is set to "true" in config.sh so that a shell script sourcing
6707           config.sh can tell if it has been sourced already.
6708
6709       "PERL_PATCHLEVEL"
6710           From Oldsyms.U:
6711
6712           This symbol reflects the patchlevel, if available. Will usually
6713           come from the .patch file, which is available when the perl source
6714           tree was fetched with rsync.
6715
6716       "perl_patchlevel"
6717           From patchlevel.U:
6718
6719           This is the Perl patch level, a numeric change identifier, as
6720           defined by whichever source code maintenance system is used to
6721           maintain the patches; currently Perforce.  It does not correlate
6722           with the Perl version numbers or the maintenance versus development
6723           dichotomy except by also being increasing.
6724
6725       "PERL_REVISION"
6726           From Oldsyms.U:
6727
6728           In a Perl version number such as 5.6.2, this is the 5.  This value
6729           is manually set in patchlevel.h
6730
6731       "perl_static_inline"
6732           From d_static_inline.U:
6733
6734           This variable defines the "PERL_STATIC_INLINE" symbol to the best-
6735           guess incantation to use for static inline functions.
6736           Possibilities include static inline       (c99) static __inline__
6737           (gcc -ansi) static __inline     ("MSVC") static _inline      (older
6738           "MSVC") static              (c89 compilers)
6739
6740       "PERL_SUBVERSION"
6741           From Oldsyms.U:
6742
6743           In a Perl version number such as 5.6.2, this is the 2.  Values
6744           greater than 50 represent potentially unstable development
6745           subversions.  This value is manually set in patchlevel.h
6746
6747       "PERL_VERSION"
6748           From Oldsyms.U:
6749
6750           In a Perl version number such as 5.6.2, this is the 6.  This value
6751           is manually set in patchlevel.h
6752
6753       "perladmin"
6754           From perladmin.U:
6755
6756           Electronic mail address of the perl5 administrator.
6757
6758       "perllibs"
6759           From End.U:
6760
6761           The list of libraries needed by Perl only (any libraries needed by
6762           extensions only will by dropped, if using dynamic loading).
6763
6764       "perlpath"
6765           From perlpath.U:
6766
6767           This variable contains the eventual value of the "PERLPATH" symbol,
6768           which contains the name of the perl interpreter to be used in shell
6769           scripts and in the "eval "exec"" idiom.  This variable is not
6770           necessarily the pathname of the file containing the perl
6771           interpreter; you must append the executable extension (_exe) if it
6772           is not already present.  Note that Perl code that runs during the
6773           Perl build process cannot reference this variable, as Perl may not
6774           have been installed, or even if installed, may be a different
6775           version of Perl.
6776
6777       "pg"
6778           From Loc.U:
6779
6780           This variable is used internally by Configure to determine the full
6781           pathname (if any) of the pg program.  After Configure runs, the
6782           value is reset to a plain "pg" and is not useful.
6783
6784       "phostname"
6785           From myhostname.U:
6786
6787           This variable contains the eventual value of the "PHOSTNAME"
6788           symbol, which is a command that can be fed to popen() to get the
6789           host name.  The program should probably not presume that the domain
6790           is or isn't there already.
6791
6792       "pidtype"
6793           From pidtype.U:
6794
6795           This variable defines "PIDTYPE" to be something like pid_t, int,
6796           ushort, or whatever type is used to declare process ids in the
6797           kernel.
6798
6799       "plibpth"
6800           From libpth.U:
6801
6802           Holds the private path used by Configure to find out the libraries.
6803           Its value is prepend to libpth. This variable takes care of special
6804           machines, like the mips.  Usually, it should be empty.
6805
6806       "pmake"
6807           From Loc.U:
6808
6809           This variable is defined but not used by Configure.  The value is
6810           the empty string and is not useful.
6811
6812       "pr"
6813           From Loc.U:
6814
6815           This variable is defined but not used by Configure.  The value is
6816           the empty string and is not useful.
6817
6818       "prefix"
6819           From prefix.U:
6820
6821           This variable holds the name of the directory below which the user
6822           will install the package.  Usually, this is /usr/local, and
6823           executables go in /usr/local/bin, library stuff in /usr/local/lib,
6824           man pages in /usr/local/man, etc.  It is only used to set defaults
6825           for things in bin.U, mansrc.U, privlib.U, or scriptdir.U.
6826
6827       "prefixexp"
6828           From prefix.U:
6829
6830           This variable holds the full absolute path of the directory below
6831           which the user will install the package.  Derived from prefix.
6832
6833       "privlib"
6834           From privlib.U:
6835
6836           This variable contains the eventual value of the "PRIVLIB" symbol,
6837           which is the name of the private library for this package.  It may
6838           have a ~ on the front. It is up to the makefile to eventually
6839           create this directory while performing installation (with ~
6840           substitution).
6841
6842       "privlibexp"
6843           From privlib.U:
6844
6845           This variable is the ~name expanded version of privlib, so that you
6846           may use it directly in Makefiles or shell scripts.
6847
6848       "procselfexe"
6849           From d_procselfexe.U:
6850
6851           If d_procselfexe is defined, $procselfexe is the filename of the
6852           symbolic link pointing to the absolute pathname of the executing
6853           program.
6854
6855       "ptrsize"
6856           From ptrsize.U:
6857
6858           This variable contains the value of the "PTRSIZE" symbol, which
6859           indicates to the C program how many bytes there are in a pointer.
6860
6861   q
6862       "quadkind"
6863           From quadtype.U:
6864
6865           This variable, if defined, encodes the type of a quad: 1 = int, 2 =
6866           long, 3 = long long, 4 = int64_t.
6867
6868       "quadtype"
6869           From quadtype.U:
6870
6871           This variable defines Quad_t to be something like long, int, long
6872           long, int64_t, or whatever type is used for 64-bit integers.
6873
6874   r
6875       "randbits"
6876           From randfunc.U:
6877
6878           Indicates how many bits are produced by the function used to
6879           generate normalized random numbers.
6880
6881       "randfunc"
6882           From randfunc.U:
6883
6884           Indicates the name of the random number function to use.  Values
6885           include drand48, random, and rand. In C programs, the "Drand01"
6886           macro is defined to generate uniformly distributed random numbers
6887           over the range [0., 1.[ (see drand01 and nrand).
6888
6889       "random_r_proto"
6890           From d_random_r.U:
6891
6892           This variable encodes the prototype of random_r.  It is zero if
6893           d_random_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
6894           of reentr.h if d_random_r is defined.
6895
6896       "randseedtype"
6897           From randfunc.U:
6898
6899           Indicates the type of the argument of the seedfunc.
6900
6901       "ranlib"
6902           From orderlib.U:
6903
6904           This variable is set to the pathname of the ranlib program, if it
6905           is needed to generate random libraries.  Set to ":" if ar can
6906           generate random libraries or if random libraries are not supported
6907
6908       "rd_nodata"
6909           From nblock_io.U:
6910
6911           This variable holds the return code from read() when no data is
6912           present. It should be -1, but some systems return 0 when "O_NDELAY"
6913           is used, which is a shame because you cannot make the difference
6914           between no data and an EOF.. Sigh!
6915
6916       "readdir64_r_proto"
6917           From d_readdir64_r.U:
6918
6919           This variable encodes the prototype of readdir64_r.  It is zero if
6920           d_readdir64_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
6921           macros of reentr.h if d_readdir64_r is defined.
6922
6923       "readdir_r_proto"
6924           From d_readdir_r.U:
6925
6926           This variable encodes the prototype of readdir_r.  It is zero if
6927           d_readdir_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
6928           of reentr.h if d_readdir_r is defined.
6929
6930       "revision"
6931           From patchlevel.U:
6932
6933           The value of revision comes from the patchlevel.h file.  In a
6934           version number such as 5.6.1, this is the 5.  In patchlevel.h, this
6935           is referred to as "PERL_REVISION".
6936
6937       "rm"
6938           From Loc.U:
6939
6940           This variable is used internally by Configure to determine the full
6941           pathname (if any) of the rm program.  After Configure runs, the
6942           value is reset to a plain "rm" and is not useful.
6943
6944       "rm_try"
6945           From Unix.U:
6946
6947           This is a cleanup variable for try test programs.  Internal
6948           Configure use only.
6949
6950       "rmail"
6951           From Loc.U:
6952
6953           This variable is defined but not used by Configure.  The value is
6954           the empty string and is not useful.
6955
6956       "run"
6957           From Cross.U:
6958
6959           This variable contains the command used by Configure to copy and
6960           execute a cross-compiled executable in the target host.  Useful and
6961           available only during Perl build.  Empty string '' if not cross-
6962           compiling.
6963
6964       "runnm"
6965           From usenm.U:
6966
6967           This variable contains "true" or "false" depending whether the nm
6968           extraction should be performed or not, according to the value of
6969           usenm and the flags on the Configure command line.
6970
6971   s
6972       "sched_yield"
6973           From d_pthread_y.U:
6974
6975           This variable defines the way to yield the execution of the current
6976           thread.
6977
6978       "scriptdir"
6979           From scriptdir.U:
6980
6981           This variable holds the name of the directory in which the user
6982           wants to put publicly scripts for the package in question.  It is
6983           either the same directory as for binaries, or a special one that
6984           can be mounted across different architectures, like /usr/share.
6985           Programs must be prepared to deal with ~name expansion.
6986
6987       "scriptdirexp"
6988           From scriptdir.U:
6989
6990           This variable is the same as scriptdir, but is filename expanded at
6991           configuration time, for programs not wanting to bother with it.
6992
6993       "sed"
6994           From Loc.U:
6995
6996           This variable is used internally by Configure to determine the full
6997           pathname (if any) of the sed program.  After Configure runs, the
6998           value is reset to a plain "sed" and is not useful.
6999
7000       "seedfunc"
7001           From randfunc.U:
7002
7003           Indicates the random number generating seed function.  Values
7004           include srand48, srandom, and srand.
7005
7006       "selectminbits"
7007           From selectminbits.U:
7008
7009           This variable holds the minimum number of bits operated by select.
7010           That is, if you do select(n, ...), how many bits at least will be
7011           cleared in the masks if some activity is detected.  Usually this is
7012           either n or 32*ceil(n/32), especially many little-endians do the
7013           latter.  This is only useful if you have select(), naturally.
7014
7015       "selecttype"
7016           From selecttype.U:
7017
7018           This variable holds the type used for the 2nd, 3rd, and 4th
7019           arguments to select.  Usually, this is "fd_set *", if "HAS_FD_SET"
7020           is defined, and "int *" otherwise.  This is only useful if you have
7021           select(), naturally.
7022
7023       "sendmail"
7024           From Loc.U:
7025
7026           This variable is defined but not used by Configure.  The value is
7027           the empty string and is not useful.
7028
7029       "setgrent_r_proto"
7030           From d_setgrent_r.U:
7031
7032           This variable encodes the prototype of setgrent_r.  It is zero if
7033           d_setgrent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
7034           macros of reentr.h if d_setgrent_r is defined.
7035
7036       "sethostent_r_proto"
7037           From d_sethostent_r.U:
7038
7039           This variable encodes the prototype of sethostent_r.  It is zero if
7040           d_sethostent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
7041           macros of reentr.h if d_sethostent_r is defined.
7042
7043       "setlocale_r_proto"
7044           From d_setlocale_r.U:
7045
7046           This variable encodes the prototype of setlocale_r.  It is zero if
7047           d_setlocale_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
7048           macros of reentr.h if d_setlocale_r is defined.
7049
7050       "setnetent_r_proto"
7051           From d_setnetent_r.U:
7052
7053           This variable encodes the prototype of setnetent_r.  It is zero if
7054           d_setnetent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
7055           macros of reentr.h if d_setnetent_r is defined.
7056
7057       "setprotoent_r_proto"
7058           From d_setprotoent_r.U:
7059
7060           This variable encodes the prototype of setprotoent_r.  It is zero
7061           if d_setprotoent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
7062           macros of reentr.h if d_setprotoent_r is defined.
7063
7064       "setpwent_r_proto"
7065           From d_setpwent_r.U:
7066
7067           This variable encodes the prototype of setpwent_r.  It is zero if
7068           d_setpwent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
7069           macros of reentr.h if d_setpwent_r is defined.
7070
7071       "setservent_r_proto"
7072           From d_setservent_r.U:
7073
7074           This variable encodes the prototype of setservent_r.  It is zero if
7075           d_setservent_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
7076           macros of reentr.h if d_setservent_r is defined.
7077
7078       "sGMTIME_max"
7079           From time_size.U:
7080
7081           This variable defines the maximum value of the time_t offset that
7082           the system function gmtime () accepts
7083
7084       "sGMTIME_min"
7085           From time_size.U:
7086
7087           This variable defines the minimum value of the time_t offset that
7088           the system function gmtime () accepts
7089
7090       "sh"
7091           From sh.U:
7092
7093           This variable contains the full pathname of the shell used on this
7094           system to execute Bourne shell scripts.  Usually, this will be
7095           /bin/sh, though it's possible that some systems will have /bin/ksh,
7096           /bin/pdksh, /bin/ash, /bin/bash, or even something such as
7097           D:/bin/sh.exe.  This unit comes before Options.U, so you can't set
7098           sh with a "-D" option, though you can override this (and startsh)
7099           with "-O -Dsh=/bin/whatever -Dstartsh=whatever"
7100
7101       "shar"
7102           From Loc.U:
7103
7104           This variable is defined but not used by Configure.  The value is
7105           the empty string and is not useful.
7106
7107       "sharpbang"
7108           From spitshell.U:
7109
7110           This variable contains the string #! if this system supports that
7111           construct.
7112
7113       "shmattype"
7114           From d_shmat.U:
7115
7116           This symbol contains the type of pointer returned by shmat().  It
7117           can be "void *" or "char *".
7118
7119       "shortsize"
7120           From intsize.U:
7121
7122           This variable contains the value of the "SHORTSIZE" symbol which
7123           indicates to the C program how many bytes there are in a short.
7124
7125       "shrpenv"
7126           From libperl.U:
7127
7128           If the user builds a shared libperl.so, then we need to tell the
7129           "perl" executable where it will be able to find the installed
7130           libperl.so.  One way to do this on some systems is to set the
7131           environment variable "LD_RUN_PATH" to the directory that will be
7132           the final location of the shared libperl.so.  The makefile can use
7133           this with something like $shrpenv $("CC") -o perl perlmain.o
7134           $libperl $libs Typical values are shrpenv="env
7135           "LD_RUN_PATH"=$archlibexp/"CORE"" or shrpenv='' See the main perl
7136           Makefile.SH for actual working usage.
7137
7138           Alternatively, we might be able to use a command line option such
7139           as -R $archlibexp/"CORE" (Solaris) or -Wl,-rpath $archlibexp/"CORE"
7140           (Linux).
7141
7142       "shsharp"
7143           From spitshell.U:
7144
7145           This variable tells further Configure units whether your sh can
7146           handle # comments.
7147
7148       "sig_count"
7149           From sig_name.U:
7150
7151           This variable holds a number larger than the largest valid signal
7152           number.  This is usually the same as the "NSIG" macro.
7153
7154       "sig_name"
7155           From sig_name.U:
7156
7157           This variable holds the signal names, space separated. The leading
7158           "SIG" in signal name is removed.  A "ZERO" is prepended to the
7159           list.  This is currently not used, sig_name_init is used instead.
7160
7161       "sig_name_init"
7162           From sig_name.U:
7163
7164           This variable holds the signal names, enclosed in double quotes and
7165           separated by commas, suitable for use in the "SIG_NAME" definition
7166           below.  A "ZERO" is prepended to the list, and the list is
7167           terminated with a plain 0.  The leading "SIG" in signal names is
7168           removed. See sig_num.
7169
7170       "sig_num"
7171           From sig_name.U:
7172
7173           This variable holds the signal numbers, space separated. A "ZERO"
7174           is prepended to the list (corresponding to the fake "SIGZERO").
7175           Those numbers correspond to  the value of the signal listed in the
7176           same place within the sig_name list.  This is currently not used,
7177           sig_num_init is used instead.
7178
7179       "sig_num_init"
7180           From sig_name.U:
7181
7182           This variable holds the signal numbers, enclosed in double quotes
7183           and separated by commas, suitable for use in the "SIG_NUM"
7184           definition below.  A "ZERO" is prepended to the list, and the list
7185           is terminated with a plain 0.
7186
7187       "sig_size"
7188           From sig_name.U:
7189
7190           This variable contains the number of elements of the sig_name and
7191           sig_num arrays.
7192
7193       "signal_t"
7194           From d_voidsig.U:
7195
7196           This variable holds the type of the signal handler (void or int).
7197
7198       "sitearch"
7199           From sitearch.U:
7200
7201           This variable contains the eventual value of the "SITEARCH" symbol,
7202           which is the name of the private library for this package.  It may
7203           have a ~ on the front. It is up to the makefile to eventually
7204           create this directory while performing installation (with ~
7205           substitution).  The standard distribution will put nothing in this
7206           directory.  After perl has been installed, users may install their
7207           own local architecture-dependent modules in this directory with
7208           MakeMaker Makefile.PL or equivalent.  See "INSTALL" for details.
7209
7210       "sitearchexp"
7211           From sitearch.U:
7212
7213           This variable is the ~name expanded version of sitearch, so that
7214           you may use it directly in Makefiles or shell scripts.
7215
7216       "sitebin"
7217           From sitebin.U:
7218
7219           This variable holds the name of the directory in which the user
7220           wants to put add-on publicly executable files for the package in
7221           question.  It is most often a local directory such as
7222           /usr/local/bin. Programs using this variable must be prepared to
7223           deal with ~name substitution.  The standard distribution will put
7224           nothing in this directory.  After perl has been installed, users
7225           may install their own local executables in this directory with
7226           MakeMaker Makefile.PL or equivalent.  See "INSTALL" for details.
7227
7228       "sitebinexp"
7229           From sitebin.U:
7230
7231           This is the same as the sitebin variable, but is filename expanded
7232           at configuration time, for use in your makefiles.
7233
7234       "sitehtml1dir"
7235           From sitehtml1dir.U:
7236
7237           This variable contains the name of the directory in which site-
7238           specific html source pages are to be put.  It is the responsibility
7239           of the Makefile.SH to get the value of this into the proper
7240           command.  You must be prepared to do the ~name expansion yourself.
7241           The standard distribution will put nothing in this directory.
7242           After perl has been installed, users may install their own local
7243           html pages in this directory with MakeMaker Makefile.PL or
7244           equivalent.  See "INSTALL" for details.
7245
7246       "sitehtml1direxp"
7247           From sitehtml1dir.U:
7248
7249           This variable is the same as the sitehtml1dir variable, but is
7250           filename expanded at configuration time, for convenient use in
7251           makefiles.
7252
7253       "sitehtml3dir"
7254           From sitehtml3dir.U:
7255
7256           This variable contains the name of the directory in which site-
7257           specific library html source pages are to be put.  It is the
7258           responsibility of the Makefile.SH to get the value of this into the
7259           proper command.  You must be prepared to do the ~name expansion
7260           yourself.  The standard distribution will put nothing in this
7261           directory.  After perl has been installed, users may install their
7262           own local library html pages in this directory with MakeMaker
7263           Makefile.PL or equivalent.  See "INSTALL" for details.
7264
7265       "sitehtml3direxp"
7266           From sitehtml3dir.U:
7267
7268           This variable is the same as the sitehtml3dir variable, but is
7269           filename expanded at configuration time, for convenient use in
7270           makefiles.
7271
7272       "sitelib"
7273           From sitelib.U:
7274
7275           This variable contains the eventual value of the "SITELIB" symbol,
7276           which is the name of the private library for this package.  It may
7277           have a ~ on the front. It is up to the makefile to eventually
7278           create this directory while performing installation (with ~
7279           substitution).  The standard distribution will put nothing in this
7280           directory.  After perl has been installed, users may install their
7281           own local architecture-independent modules in this directory with
7282           MakeMaker Makefile.PL or equivalent.  See "INSTALL" for details.
7283
7284       "sitelib_stem"
7285           From sitelib.U:
7286
7287           This variable is $sitelibexp with any trailing version-specific
7288           component removed.  The elements in inc_version_list
7289           (inc_version_list.U) can be tacked onto this variable to generate a
7290           list of directories to search.
7291
7292       "sitelibexp"
7293           From sitelib.U:
7294
7295           This variable is the ~name expanded version of sitelib, so that you
7296           may use it directly in Makefiles or shell scripts.
7297
7298       "siteman1dir"
7299           From siteman1dir.U:
7300
7301           This variable contains the name of the directory in which site-
7302           specific manual source pages are to be put.  It is the
7303           responsibility of the Makefile.SH to get the value of this into the
7304           proper command.  You must be prepared to do the ~name expansion
7305           yourself.  The standard distribution will put nothing in this
7306           directory.  After perl has been installed, users may install their
7307           own local man1 pages in this directory with MakeMaker Makefile.PL
7308           or equivalent.  See "INSTALL" for details.
7309
7310       "siteman1direxp"
7311           From siteman1dir.U:
7312
7313           This variable is the same as the siteman1dir variable, but is
7314           filename expanded at configuration time, for convenient use in
7315           makefiles.
7316
7317       "siteman3dir"
7318           From siteman3dir.U:
7319
7320           This variable contains the name of the directory in which site-
7321           specific library man source pages are to be put.  It is the
7322           responsibility of the Makefile.SH to get the value of this into the
7323           proper command.  You must be prepared to do the ~name expansion
7324           yourself.  The standard distribution will put nothing in this
7325           directory.  After perl has been installed, users may install their
7326           own local man3 pages in this directory with MakeMaker Makefile.PL
7327           or equivalent.  See "INSTALL" for details.
7328
7329       "siteman3direxp"
7330           From siteman3dir.U:
7331
7332           This variable is the same as the siteman3dir variable, but is
7333           filename expanded at configuration time, for convenient use in
7334           makefiles.
7335
7336       "siteprefix"
7337           From siteprefix.U:
7338
7339           This variable holds the full absolute path of the directory below
7340           which the user will install add-on packages.  See "INSTALL" for
7341           usage and examples.
7342
7343       "siteprefixexp"
7344           From siteprefix.U:
7345
7346           This variable holds the full absolute path of the directory below
7347           which the user will install add-on packages.  Derived from
7348           siteprefix.
7349
7350       "sitescript"
7351           From sitescript.U:
7352
7353           This variable holds the name of the directory in which the user
7354           wants to put add-on publicly executable files for the package in
7355           question.  It is most often a local directory such as
7356           /usr/local/bin. Programs using this variable must be prepared to
7357           deal with ~name substitution.  The standard distribution will put
7358           nothing in this directory.  After perl has been installed, users
7359           may install their own local scripts in this directory with
7360           MakeMaker Makefile.PL or equivalent.  See "INSTALL" for details.
7361
7362       "sitescriptexp"
7363           From sitescript.U:
7364
7365           This is the same as the sitescript variable, but is filename
7366           expanded at configuration time, for use in your makefiles.
7367
7368       "sizesize"
7369           From sizesize.U:
7370
7371           This variable contains the size of a sizetype in bytes.
7372
7373       "sizetype"
7374           From sizetype.U:
7375
7376           This variable defines sizetype to be something like size_t,
7377           unsigned long, or whatever type is used to declare length
7378           parameters for string functions.
7379
7380       "sleep"
7381           From Loc.U:
7382
7383           This variable is defined but not used by Configure.  The value is
7384           the empty string and is not useful.
7385
7386       "sLOCALTIME_max"
7387           From time_size.U:
7388
7389           This variable defines the maximum value of the time_t offset that
7390           the system function localtime () accepts
7391
7392       "sLOCALTIME_min"
7393           From time_size.U:
7394
7395           This variable defines the minimum value of the time_t offset that
7396           the system function localtime () accepts
7397
7398       "smail"
7399           From Loc.U:
7400
7401           This variable is defined but not used by Configure.  The value is
7402           the empty string and is not useful.
7403
7404       "so"
7405           From so.U:
7406
7407           This variable holds the extension used to identify shared libraries
7408           (also known as shared objects) on the system. Usually set to "so".
7409
7410       "sockethdr"
7411           From d_socket.U:
7412
7413           This variable has any cpp "-I" flags needed for socket support.
7414
7415       "socketlib"
7416           From d_socket.U:
7417
7418           This variable has the names of any libraries needed for socket
7419           support.
7420
7421       "socksizetype"
7422           From socksizetype.U:
7423
7424           This variable holds the type used for the size argument for various
7425           socket calls like accept.  Usual values include socklen_t, size_t,
7426           and int.
7427
7428       "sort"
7429           From Loc.U:
7430
7431           This variable is used internally by Configure to determine the full
7432           pathname (if any) of the sort program.  After Configure runs, the
7433           value is reset to a plain "sort" and is not useful.
7434
7435       "spackage"
7436           From package.U:
7437
7438           This variable contains the name of the package being constructed,
7439           with the first letter uppercased, i.e. suitable for starting
7440           sentences.
7441
7442       "spitshell"
7443           From spitshell.U:
7444
7445           This variable contains the command necessary to spit out a runnable
7446           shell on this system.  It is either cat or a grep "-v" for #
7447           comments.
7448
7449       "sPRId64"
7450           From quadfio.U:
7451
7452           This variable, if defined, contains the string used by stdio to
7453           format 64-bit decimal numbers (format "d") for output.
7454
7455       "sPRIeldbl"
7456           From longdblfio.U:
7457
7458           This variable, if defined, contains the string used by stdio to
7459           format long doubles (format "e") for output.
7460
7461       "sPRIEUldbl"
7462           From longdblfio.U:
7463
7464           This variable, if defined, contains the string used by stdio to
7465           format long doubles (format "E") for output.  The "U" in the name
7466           is to separate this from sPRIeldbl so that even case-blind systems
7467           can see the difference.
7468
7469       "sPRIfldbl"
7470           From longdblfio.U:
7471
7472           This variable, if defined, contains the string used by stdio to
7473           format long doubles (format "f") for output.
7474
7475       "sPRIFUldbl"
7476           From longdblfio.U:
7477
7478           This variable, if defined, contains the string used by stdio to
7479           format long doubles (format "F") for output.  The "U" in the name
7480           is to separate this from sPRIfldbl so that even case-blind systems
7481           can see the difference.
7482
7483       "sPRIgldbl"
7484           From longdblfio.U:
7485
7486           This variable, if defined, contains the string used by stdio to
7487           format long doubles (format "g") for output.
7488
7489       "sPRIGUldbl"
7490           From longdblfio.U:
7491
7492           This variable, if defined, contains the string used by stdio to
7493           format long doubles (format "G") for output.  The "U" in the name
7494           is to separate this from sPRIgldbl so that even case-blind systems
7495           can see the difference.
7496
7497       "sPRIi64"
7498           From quadfio.U:
7499
7500           This variable, if defined, contains the string used by stdio to
7501           format 64-bit decimal numbers (format "i") for output.
7502
7503       "sPRIo64"
7504           From quadfio.U:
7505
7506           This variable, if defined, contains the string used by stdio to
7507           format 64-bit octal numbers (format "o") for output.
7508
7509       "sPRIu64"
7510           From quadfio.U:
7511
7512           This variable, if defined, contains the string used by stdio to
7513           format 64-bit unsigned decimal numbers (format "u") for output.
7514
7515       "sPRIx64"
7516           From quadfio.U:
7517
7518           This variable, if defined, contains the string used by stdio to
7519           format 64-bit hexadecimal numbers (format "x") for output.
7520
7521       "sPRIXU64"
7522           From quadfio.U:
7523
7524           This variable, if defined, contains the string used by stdio to
7525           format 64-bit hExADECimAl numbers (format "X") for output.  The "U"
7526           in the name is to separate this from sPRIx64 so that even case-
7527           blind systems can see the difference.
7528
7529       "srand48_r_proto"
7530           From d_srand48_r.U:
7531
7532           This variable encodes the prototype of srand48_r.  It is zero if
7533           d_srand48_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
7534           of reentr.h if d_srand48_r is defined.
7535
7536       "srandom_r_proto"
7537           From d_srandom_r.U:
7538
7539           This variable encodes the prototype of srandom_r.  It is zero if
7540           d_srandom_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
7541           of reentr.h if d_srandom_r is defined.
7542
7543       "src"
7544           From src.U:
7545
7546           This variable holds the (possibly relative) path of the package
7547           source.  It is up to the Makefile to use this variable and set
7548           "VPATH" accordingly to find the sources remotely.  Use $pkgsrc to
7549           have an absolute path.
7550
7551       "sSCNfldbl"
7552           From longdblfio.U:
7553
7554           This variable, if defined, contains the string used by stdio to
7555           format long doubles (format "f") for input.
7556
7557       "ssizetype"
7558           From ssizetype.U:
7559
7560           This variable defines ssizetype to be something like ssize_t, long
7561           or int.  It is used by functions that return a count of bytes or an
7562           error condition.  It must be a signed type.  We will pick a type
7563           such that sizeof(SSize_t) == sizeof(Size_t).
7564
7565       "st_ino_sign"
7566           From st_ino_def.U:
7567
7568           This variable contains the signedness of struct stat's st_ino.  1
7569           for unsigned, -1 for signed.
7570
7571       "st_ino_size"
7572           From st_ino_def.U:
7573
7574           This variable contains the size of struct stat's st_ino in bytes.
7575
7576       "startperl"
7577           From startperl.U:
7578
7579           This variable contains the string to put on the front of a perl
7580           script to make sure (hopefully) that it runs with perl and not some
7581           shell. Of course, that leading line must be followed by the
7582           classical perl idiom: eval 'exec perl -S $0 ${1+$@}' if
7583           $running_under_some_shell; to guarantee perl startup should the
7584           shell execute the script. Note that this magic incantation is not
7585           understood by csh.
7586
7587       "startsh"
7588           From startsh.U:
7589
7590           This variable contains the string to put on the front of a shell
7591           script to make sure (hopefully) that it runs with sh and not some
7592           other shell.
7593
7594       "static_ext"
7595           From Extensions.U:
7596
7597           This variable holds a list of "XS" extension files we want to link
7598           statically into the package.  It is used by Makefile.
7599
7600       "stdchar"
7601           From stdchar.U:
7602
7603           This variable conditionally defines "STDCHAR" to be the type of
7604           char used in stdio.h.  It has the values "unsigned char" or "char".
7605
7606       "stdio_base"
7607           From d_stdstdio.U:
7608
7609           This variable defines how, given a "FILE" pointer, fp, to access
7610           the _base field (or equivalent) of stdio.h's "FILE" structure.
7611           This will be used to define the macro FILE_base(fp).
7612
7613       "stdio_bufsiz"
7614           From d_stdstdio.U:
7615
7616           This variable defines how, given a "FILE" pointer, fp, to determine
7617           the number of bytes store in the I/O buffer pointer to by the _base
7618           field (or equivalent) of stdio.h's "FILE" structure.  This will be
7619           used to define the macro FILE_bufsiz(fp).
7620
7621       "stdio_cnt"
7622           From d_stdstdio.U:
7623
7624           This variable defines how, given a "FILE" pointer, fp, to access
7625           the _cnt field (or equivalent) of stdio.h's "FILE" structure.  This
7626           will be used to define the macro FILE_cnt(fp).
7627
7628       "stdio_filbuf"
7629           From d_stdstdio.U:
7630
7631           This variable defines how, given a "FILE" pointer, fp, to tell
7632           stdio to refill its internal buffers (?).  This will be used to
7633           define the macro FILE_filbuf(fp).
7634
7635       "stdio_ptr"
7636           From d_stdstdio.U:
7637
7638           This variable defines how, given a "FILE" pointer, fp, to access
7639           the _ptr field (or equivalent) of stdio.h's "FILE" structure.  This
7640           will be used to define the macro FILE_ptr(fp).
7641
7642       "stdio_stream_array"
7643           From stdio_streams.U:
7644
7645           This variable tells the name of the array holding the stdio
7646           streams.  Usual values include _iob, __iob, and __sF.
7647
7648       "strerror_r_proto"
7649           From d_strerror_r.U:
7650
7651           This variable encodes the prototype of strerror_r.  It is zero if
7652           d_strerror_r is undef, and one of the "REENTRANT_PROTO_T_ABC"
7653           macros of reentr.h if d_strerror_r is defined.
7654
7655       "submit"
7656           From Loc.U:
7657
7658           This variable is defined but not used by Configure.  The value is
7659           the empty string and is not useful.
7660
7661       "subversion"
7662           From patchlevel.U:
7663
7664           The subversion level of this package.  The value of subversion
7665           comes from the patchlevel.h file.  In a version number such as
7666           5.6.1, this is the 1.  In patchlevel.h, this is referred to as
7667           "PERL_SUBVERSION".  This is unique to perl.
7668
7669       "sysman"
7670           From sysman.U:
7671
7672           This variable holds the place where the manual is located on this
7673           system. It is not the place where the user wants to put his manual
7674           pages. Rather it is the place where Configure may look to find
7675           manual for unix commands (section 1 of the manual usually). See
7676           mansrc.
7677
7678       "sysroot"
7679           From Sysroot.U:
7680
7681           This variable is empty unless supplied by the Configure user.  It
7682           can contain a path to an alternative root directory, under which
7683           headers and libraries for the compilation target can be found. This
7684           is generally used when cross-compiling using a gcc-like compiler.
7685
7686   t
7687       "tail"
7688           From Loc.U:
7689
7690           This variable is defined but not used by Configure.  The value is
7691           the empty string and is not useful.
7692
7693       "tar"
7694           From Loc.U:
7695
7696           This variable is defined but not used by Configure.  The value is
7697           the empty string and is not useful.
7698
7699       "targetarch"
7700           From Cross.U:
7701
7702           If cross-compiling, this variable contains the target architecture.
7703           If not, this will be empty.
7704
7705       "targetdir"
7706           From Cross.U:
7707
7708           This variable contains a path that will be created on the target
7709           host using targetmkdir, and then used to copy the cross-compiled
7710           executables to. Defaults to /tmp if not set.
7711
7712       "targetenv"
7713           From Cross.U:
7714
7715           If cross-compiling, this variable can be used to modify the
7716           environment on the target system.  However, how and where it's
7717           used, and even if it's used at all, is entirely dependent on both
7718           the transport mechanism (targetrun) and what the target system is.
7719           Unless the relevant documentation says otherwise, it is genereally
7720           not useful.
7721
7722       "targethost"
7723           From Cross.U:
7724
7725           This variable contains the name of a separate host machine that can
7726           be used to run compiled test programs and perl tests on.  Set to
7727           empty string if not in use.
7728
7729       "targetmkdir"
7730           From Cross.U:
7731
7732           This variable contains the command used by Configure to create a
7733           new directory on the target host.
7734
7735       "targetport"
7736           From Cross.U:
7737
7738           This variable contains the number of a network port to be used to
7739           connect to the host in targethost, if unset defaults to 22 for ssh.
7740
7741       "targetsh"
7742           From sh.U:
7743
7744           If cross-compiling, this variable contains the location of sh on
7745           the target system.  If not, this will be the same as $sh.
7746
7747       "tbl"
7748           From Loc.U:
7749
7750           This variable is defined but not used by Configure.  The value is
7751           the empty string and is not useful.
7752
7753       "tee"
7754           From Loc.U:
7755
7756           This variable is defined but not used by Configure.  The value is
7757           the empty string and is not useful.
7758
7759       "test"
7760           From Loc.U:
7761
7762           This variable is used internally by Configure to determine the full
7763           pathname (if any) of the test program.  After Configure runs, the
7764           value is reset to a plain "test" and is not useful.
7765
7766       "timeincl"
7767           From i_time.U:
7768
7769           This variable holds the full path of the included time header(s).
7770
7771       "timetype"
7772           From d_time.U:
7773
7774           This variable holds the type returned by time(). It can be long, or
7775           time_t on "BSD" sites (in which case <sys/types.h> should be
7776           included). Anyway, the type Time_t should be used.
7777
7778       "tmpnam_r_proto"
7779           From d_tmpnam_r.U:
7780
7781           This variable encodes the prototype of tmpnam_r.  It is zero if
7782           d_tmpnam_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
7783           of reentr.h if d_tmpnam_r is defined.
7784
7785       "to"
7786           From Cross.U:
7787
7788           This variable contains the command used by Configure to copy to
7789           from the target host.  Useful and available only during Perl build.
7790           The string ":" if not cross-compiling.
7791
7792       "touch"
7793           From Loc.U:
7794
7795           This variable is used internally by Configure to determine the full
7796           pathname (if any) of the touch program.  After Configure runs, the
7797           value is reset to a plain "touch" and is not useful.
7798
7799       "tr"
7800           From Loc.U:
7801
7802           This variable is used internally by Configure to determine the full
7803           pathname (if any) of the tr program.  After Configure runs, the
7804           value is reset to a plain "tr" and is not useful.
7805
7806       "trnl"
7807           From trnl.U:
7808
7809           This variable contains the value to be passed to the tr(1) command
7810           to transliterate a newline.  Typical values are "\012" and "\n".
7811           This is needed for "EBCDIC" systems where newline is not
7812           necessarily "\012".
7813
7814       "troff"
7815           From Loc.U:
7816
7817           This variable is defined but not used by Configure.  The value is
7818           the empty string and is not useful.
7819
7820       "ttyname_r_proto"
7821           From d_ttyname_r.U:
7822
7823           This variable encodes the prototype of ttyname_r.  It is zero if
7824           d_ttyname_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros
7825           of reentr.h if d_ttyname_r is defined.
7826
7827   u
7828       "u16size"
7829           From perlxv.U:
7830
7831           This variable is the size of an U16 in bytes.
7832
7833       "u16type"
7834           From perlxv.U:
7835
7836           This variable contains the C type used for Perl's U16.
7837
7838       "u32size"
7839           From perlxv.U:
7840
7841           This variable is the size of an U32 in bytes.
7842
7843       "u32type"
7844           From perlxv.U:
7845
7846           This variable contains the C type used for Perl's U32.
7847
7848       "u64size"
7849           From perlxv.U:
7850
7851           This variable is the size of an U64 in bytes.
7852
7853       "u64type"
7854           From perlxv.U:
7855
7856           This variable contains the C type used for Perl's U64.
7857
7858       "u8size"
7859           From perlxv.U:
7860
7861           This variable is the size of an U8 in bytes.
7862
7863       "u8type"
7864           From perlxv.U:
7865
7866           This variable contains the C type used for Perl's U8.
7867
7868       "uidformat"
7869           From uidf.U:
7870
7871           This variable contains the format string used for printing a Uid_t.
7872
7873       "uidsign"
7874           From uidsign.U:
7875
7876           This variable contains the signedness of a uidtype.  1 for
7877           unsigned, -1 for signed.
7878
7879       "uidsize"
7880           From uidsize.U:
7881
7882           This variable contains the size of a uidtype in bytes.
7883
7884       "uidtype"
7885           From uidtype.U:
7886
7887           This variable defines Uid_t to be something like uid_t, int,
7888           ushort, or whatever type is used to declare user ids in the kernel.
7889
7890       "uname"
7891           From Loc.U:
7892
7893           This variable is used internally by Configure to determine the full
7894           pathname (if any) of the uname program.  After Configure runs, the
7895           value is reset to a plain "uname" and is not useful.
7896
7897       "uniq"
7898           From Loc.U:
7899
7900           This variable is used internally by Configure to determine the full
7901           pathname (if any) of the uniq program.  After Configure runs, the
7902           value is reset to a plain "uniq" and is not useful.
7903
7904       "uquadtype"
7905           From quadtype.U:
7906
7907           This variable defines Uquad_t to be something like unsigned long,
7908           unsigned int, unsigned long long, uint64_t, or whatever type is
7909           used for 64-bit integers.
7910
7911       "use5005threads"
7912           From usethreads.U:
7913
7914           This variable conditionally defines the USE_5005THREADS symbol, and
7915           indicates that Perl should be built to use the 5.005-based
7916           threading implementation. Only valid up to 5.8.x.
7917
7918       "use64bitall"
7919           From use64bits.U:
7920
7921           This variable conditionally defines the USE_64_BIT_ALL symbol, and
7922           indicates that 64-bit integer types should be used when available.
7923           The maximal possible 64-bitness is employed: LP64 or ILP64, meaning
7924           that you will be able to use more than 2 gigabytes of memory.  This
7925           mode is even more binary incompatible than USE_64_BIT_INT. You may
7926           not be able to run the resulting executable in a 32-bit "CPU" at
7927           all or you may need at least to reboot your "OS" to 64-bit mode.
7928
7929       "use64bitint"
7930           From use64bits.U:
7931
7932           This variable conditionally defines the USE_64_BIT_INT symbol, and
7933           indicates that 64-bit integer types should be used when available.
7934           The minimal possible 64-bitness is employed, just enough to get
7935           64-bit integers into Perl.  This may mean using for example "long
7936           longs", while your memory may still be limited to 2 gigabytes.
7937
7938       "usecbacktrace"
7939           From usebacktrace.U:
7940
7941           This variable indicates whether we are compiling with backtrace
7942           support.
7943
7944       "usecrosscompile"
7945           From Cross.U:
7946
7947           This variable conditionally defines the "USE_CROSS_COMPILE" symbol,
7948           and indicates that Perl has been cross-compiled.
7949
7950       "usedevel"
7951           From Devel.U:
7952
7953           This variable indicates that Perl was configured with development
7954           features enabled.  This should not be done for production builds.
7955
7956       "usedl"
7957           From dlsrc.U:
7958
7959           This variable indicates if the system supports dynamic loading of
7960           some sort.  See also dlsrc and dlobj.
7961
7962       "usedtrace"
7963           From usedtrace.U:
7964
7965           This variable indicates whether we are compiling with dtrace
7966           support. See also dtrace.
7967
7968       "usefaststdio"
7969           From usefaststdio.U:
7970
7971           This variable conditionally defines the "USE_FAST_STDIO" symbol,
7972           and indicates that Perl should be built to use "fast stdio".
7973           Defaults to define in Perls 5.8 and earlier, to undef later.
7974
7975       "useithreads"
7976           From usethreads.U:
7977
7978           This variable conditionally defines the "USE_ITHREADS" symbol, and
7979           indicates that Perl should be built to use the interpreter-based
7980           threading implementation.
7981
7982       "usekernprocpathname"
7983           From usekernprocpathname.U:
7984
7985           This variable, indicates that we can use sysctl with
7986           "KERN_PROC_PATHNAME" to get a full path for the executable, and
7987           hence convert $^X to an absolute path.
7988
7989       "uselanginfo"
7990           From Extensions.U:
7991
7992           This variable holds either "true" or "false" to indicate whether
7993           the I18N::Langinfo extension should be used.  The sole use for this
7994           currently is to allow an easy mechanism for users to skip this
7995           extension from the Configure command line.
7996
7997       "uselargefiles"
7998           From uselfs.U:
7999
8000           This variable conditionally defines the "USE_LARGE_FILES" symbol,
8001           and indicates that large file interfaces should be used when
8002           available.
8003
8004       "uselongdouble"
8005           From uselongdbl.U:
8006
8007           This variable conditionally defines the "USE_LONG_DOUBLE" symbol,
8008           and indicates that long doubles should be used when available.
8009
8010       "usemallocwrap"
8011           From mallocsrc.U:
8012
8013           This variable contains y if we are wrapping malloc to prevent
8014           integer overflow during size calculations.
8015
8016       "usemorebits"
8017           From usemorebits.U:
8018
8019           This variable conditionally defines the "USE_MORE_BITS" symbol, and
8020           indicates that explicit 64-bit interfaces and long doubles should
8021           be used when available.
8022
8023       "usemultiplicity"
8024           From usemultiplicity.U:
8025
8026           This variable conditionally defines the "MULTIPLICITY" symbol, and
8027           indicates that Perl should be built to use multiplicity.
8028
8029       "usemymalloc"
8030           From mallocsrc.U:
8031
8032           This variable contains y if the malloc that comes with this package
8033           is desired over the system's version of malloc.  People often
8034           include special versions of malloc for efficiency, but such
8035           versions are often less portable.  See also mallocsrc and
8036           mallocobj.  If this is "y", then -lmalloc is removed from $libs.
8037
8038       "usenm"
8039           From usenm.U:
8040
8041           This variable contains "true" or "false" depending whether the nm
8042           extraction is wanted or not.
8043
8044       "usensgetexecutablepath"
8045           From usensgetexecutablepath.U:
8046
8047           This symbol, if defined, indicates that we can use
8048           _NSGetExecutablePath and realpath to get a full path for the
8049           executable, and hence convert $^X to an absolute path.
8050
8051       "useopcode"
8052           From Extensions.U:
8053
8054           This variable holds either "true" or "false" to indicate whether
8055           the Opcode extension should be used.  The sole use for this
8056           currently is to allow an easy mechanism for users to skip the
8057           Opcode extension from the Configure command line.
8058
8059       "useperlio"
8060           From useperlio.U:
8061
8062           This variable conditionally defines the "USE_PERLIO" symbol, and
8063           indicates that the PerlIO abstraction should be used throughout.
8064
8065       "useposix"
8066           From Extensions.U:
8067
8068           This variable holds either "true" or "false" to indicate whether
8069           the "POSIX" extension should be used.  The sole use for this
8070           currently is to allow an easy mechanism for hints files to indicate
8071           that "POSIX" will not compile on a particular system.
8072
8073       "usequadmath"
8074           From usequadmath.U:
8075
8076           This variable conditionally defines the "USE_QUADMATH" symbol, and
8077           indicates that the quadmath library __float128 long doubles should
8078           be used when available.
8079
8080       "usereentrant"
8081           From usethreads.U:
8082
8083           This variable conditionally defines the "USE_REENTRANT_API" symbol,
8084           which indicates that the thread code may try to use the various _r
8085           versions of library functions.  This is only potentially meaningful
8086           if usethreads is set and is very experimental, it is not even
8087           prompted for.
8088
8089       "userelocatableinc"
8090           From bin.U:
8091
8092           This variable is set to true to indicate that perl should relocate
8093           @"INC" entries at runtime based on the path to the perl binary.
8094           Any @"INC" paths starting .../ are relocated relative to the
8095           directory containing the perl binary, and a logical cleanup of the
8096           path is then made around the join point (removing dir/../ pairs)
8097
8098       "useshrplib"
8099           From libperl.U:
8100
8101           This variable is set to "true" if the user wishes to build a shared
8102           libperl, and "false" otherwise.
8103
8104       "usesitecustomize"
8105           From d_sitecustomize.U:
8106
8107           This variable is set to true when the user requires a mechanism
8108           that allows the sysadmin to add entries to @"INC" at runtime.  This
8109           variable being set, makes perl run $sitelib/sitecustomize.pl at
8110           startup.
8111
8112       "usesocks"
8113           From usesocks.U:
8114
8115           This variable conditionally defines the "USE_SOCKS" symbol, and
8116           indicates that Perl should be built to use "SOCKS".
8117
8118       "usethreads"
8119           From usethreads.U:
8120
8121           This variable conditionally defines the "USE_THREADS" symbol, and
8122           indicates that Perl should be built to use threads.
8123
8124       "usevendorprefix"
8125           From vendorprefix.U:
8126
8127           This variable tells whether the vendorprefix and consequently other
8128           vendor* paths are in use.
8129
8130       "useversionedarchname"
8131           From archname.U:
8132
8133           This variable indicates whether to include the $api_versionstring
8134           as a component of the $archname.
8135
8136       "usevfork"
8137           From d_vfork.U:
8138
8139           This variable is set to true when the user accepts to use vfork.
8140           It is set to false when no vfork is available or when the user
8141           explicitly requests not to use vfork.
8142
8143       "usrinc"
8144           From usrinc.U:
8145
8146           This variable holds the path of the include files, which is usually
8147           /usr/include. It is mainly used by other Configure units.
8148
8149       "uuname"
8150           From Loc.U:
8151
8152           This variable is defined but not used by Configure.  The value is
8153           the empty string and is not useful.
8154
8155       "uvoformat"
8156           From perlxvf.U:
8157
8158           This variable contains the format string used for printing a Perl
8159           "UV" as an unsigned octal integer.
8160
8161       "uvsize"
8162           From perlxv.U:
8163
8164           This variable is the size of a "UV" in bytes.
8165
8166       "uvtype"
8167           From perlxv.U:
8168
8169           This variable contains the C type used for Perl's "UV".
8170
8171       "uvuformat"
8172           From perlxvf.U:
8173
8174           This variable contains the format string used for printing a Perl
8175           "UV" as an unsigned decimal integer.
8176
8177       "uvxformat"
8178           From perlxvf.U:
8179
8180           This variable contains the format string used for printing a Perl
8181           "UV" as an unsigned hexadecimal integer in lowercase abcdef.
8182
8183       "uvXUformat"
8184           From perlxvf.U:
8185
8186           This variable contains the format string used for printing a Perl
8187           "UV" as an unsigned hexadecimal integer in uppercase "ABCDEF".
8188
8189   v
8190       "vendorarch"
8191           From vendorarch.U:
8192
8193           This variable contains the value of the "PERL_VENDORARCH" symbol.
8194           It may have a ~ on the front.  The standard distribution will put
8195           nothing in this directory.  Vendors who distribute perl may wish to
8196           place their own architecture-dependent modules and extensions in
8197           this directory with MakeMaker Makefile.PL "INSTALLDIRS"=vendor or
8198           equivalent.  See "INSTALL" for details.
8199
8200       "vendorarchexp"
8201           From vendorarch.U:
8202
8203           This variable is the ~name expanded version of vendorarch, so that
8204           you may use it directly in Makefiles or shell scripts.
8205
8206       "vendorbin"
8207           From vendorbin.U:
8208
8209           This variable contains the eventual value of the "VENDORBIN"
8210           symbol.  It may have a ~ on the front.  The standard distribution
8211           will put nothing in this directory.  Vendors who distribute perl
8212           may wish to place additional binaries in this directory with
8213           MakeMaker Makefile.PL "INSTALLDIRS"=vendor or equivalent.  See
8214           "INSTALL" for details.
8215
8216       "vendorbinexp"
8217           From vendorbin.U:
8218
8219           This variable is the ~name expanded version of vendorbin, so that
8220           you may use it directly in Makefiles or shell scripts.
8221
8222       "vendorhtml1dir"
8223           From vendorhtml1dir.U:
8224
8225           This variable contains the name of the directory for html pages.
8226           It may have a ~ on the front.  The standard distribution will put
8227           nothing in this directory.  Vendors who distribute perl may wish to
8228           place their own html pages in this directory with MakeMaker
8229           Makefile.PL "INSTALLDIRS"=vendor or equivalent.  See "INSTALL" for
8230           details.
8231
8232       "vendorhtml1direxp"
8233           From vendorhtml1dir.U:
8234
8235           This variable is the ~name expanded version of vendorhtml1dir, so
8236           that you may use it directly in Makefiles or shell scripts.
8237
8238       "vendorhtml3dir"
8239           From vendorhtml3dir.U:
8240
8241           This variable contains the name of the directory for html library
8242           pages.  It may have a ~ on the front.  The standard distribution
8243           will put nothing in this directory.  Vendors who distribute perl
8244           may wish to place their own html pages for modules and extensions
8245           in this directory with MakeMaker Makefile.PL "INSTALLDIRS"=vendor
8246           or equivalent.  See "INSTALL" for details.
8247
8248       "vendorhtml3direxp"
8249           From vendorhtml3dir.U:
8250
8251           This variable is the ~name expanded version of vendorhtml3dir, so
8252           that you may use it directly in Makefiles or shell scripts.
8253
8254       "vendorlib"
8255           From vendorlib.U:
8256
8257           This variable contains the eventual value of the "VENDORLIB"
8258           symbol, which is the name of the private library for this package.
8259           The standard distribution will put nothing in this directory.
8260           Vendors who distribute perl may wish to place their own modules in
8261           this directory with MakeMaker Makefile.PL "INSTALLDIRS"=vendor or
8262           equivalent.  See "INSTALL" for details.
8263
8264       "vendorlib_stem"
8265           From vendorlib.U:
8266
8267           This variable is $vendorlibexp with any trailing version-specific
8268           component removed.  The elements in inc_version_list
8269           (inc_version_list.U) can be tacked onto this variable to generate a
8270           list of directories to search.
8271
8272       "vendorlibexp"
8273           From vendorlib.U:
8274
8275           This variable is the ~name expanded version of vendorlib, so that
8276           you may use it directly in Makefiles or shell scripts.
8277
8278       "vendorman1dir"
8279           From vendorman1dir.U:
8280
8281           This variable contains the name of the directory for man1 pages.
8282           It may have a ~ on the front.  The standard distribution will put
8283           nothing in this directory.  Vendors who distribute perl may wish to
8284           place their own man1 pages in this directory with MakeMaker
8285           Makefile.PL "INSTALLDIRS"=vendor or equivalent.  See "INSTALL" for
8286           details.
8287
8288       "vendorman1direxp"
8289           From vendorman1dir.U:
8290
8291           This variable is the ~name expanded version of vendorman1dir, so
8292           that you may use it directly in Makefiles or shell scripts.
8293
8294       "vendorman3dir"
8295           From vendorman3dir.U:
8296
8297           This variable contains the name of the directory for man3 pages.
8298           It may have a ~ on the front.  The standard distribution will put
8299           nothing in this directory.  Vendors who distribute perl may wish to
8300           place their own man3 pages in this directory with MakeMaker
8301           Makefile.PL "INSTALLDIRS"=vendor or equivalent.  See "INSTALL" for
8302           details.
8303
8304       "vendorman3direxp"
8305           From vendorman3dir.U:
8306
8307           This variable is the ~name expanded version of vendorman3dir, so
8308           that you may use it directly in Makefiles or shell scripts.
8309
8310       "vendorprefix"
8311           From vendorprefix.U:
8312
8313           This variable holds the full absolute path of the directory below
8314           which the vendor will install add-on packages.  See "INSTALL" for
8315           usage and examples.
8316
8317       "vendorprefixexp"
8318           From vendorprefix.U:
8319
8320           This variable holds the full absolute path of the directory below
8321           which the vendor will install add-on packages.  Derived from
8322           vendorprefix.
8323
8324       "vendorscript"
8325           From vendorscript.U:
8326
8327           This variable contains the eventual value of the "VENDORSCRIPT"
8328           symbol.  It may have a ~ on the front.  The standard distribution
8329           will put nothing in this directory.  Vendors who distribute perl
8330           may wish to place additional executable scripts in this directory
8331           with MakeMaker Makefile.PL "INSTALLDIRS"=vendor or equivalent.  See
8332           "INSTALL" for details.
8333
8334       "vendorscriptexp"
8335           From vendorscript.U:
8336
8337           This variable is the ~name expanded version of vendorscript, so
8338           that you may use it directly in Makefiles or shell scripts.
8339
8340       "version"
8341           From patchlevel.U:
8342
8343           The full version number of this package, such as 5.6.1 (or 5_6_1).
8344           This combines revision, patchlevel, and subversion to get the full
8345           version number, including any possible subversions.  This is
8346           suitable for use as a directory name, and hence is filesystem
8347           dependent.
8348
8349       "version_patchlevel_string"
8350           From patchlevel.U:
8351
8352           This is a string combining version, subversion and perl_patchlevel
8353           (if perl_patchlevel is non-zero).  It is typically something like
8354           'version 7 subversion 1'  or 'version 7 subversion 1 patchlevel
8355           11224' It is computed here to avoid duplication of code in
8356           myconfig.SH and lib/Config.pm.
8357
8358       "versiononly"
8359           From versiononly.U:
8360
8361           If set, this symbol indicates that only the version-specific
8362           components of a perl installation should be installed.  This may be
8363           useful for making a test installation of a new version without
8364           disturbing the existing installation.  Setting versiononly is
8365           equivalent to setting installperl's -v option.  In particular, the
8366           non-versioned scripts and programs such as a2p, c2ph, h2xs, pod2*,
8367           and perldoc are not installed (see "INSTALL" for a more complete
8368           list).  Nor are the man pages installed.  Usually, this is undef.
8369
8370       "vi"
8371           From Loc.U:
8372
8373           This variable is defined but not used by Configure.  The value is
8374           the empty string and is not useful.
8375
8376   x
8377       "xlibpth"
8378           From libpth.U:
8379
8380           This variable holds extra path (space-separated) used to find
8381           libraries on this platform, for example "CPU"-specific libraries
8382           (on multi-"CPU" platforms) may be listed here.
8383
8384   y
8385       "yacc"
8386           From yacc.U:
8387
8388           This variable holds the name of the compiler compiler we want to
8389           use in the Makefile. It can be yacc, byacc, or bison -y.
8390
8391       "yaccflags"
8392           From yacc.U:
8393
8394           This variable contains any additional yacc flags desired by the
8395           user.  It is up to the Makefile to use this.
8396
8397   z
8398       "zcat"
8399           From Loc.U:
8400
8401           This variable is defined but not used by Configure.  The value is
8402           the empty string and is not useful.
8403
8404       "zip"
8405           From Loc.U:
8406
8407           This variable is used internally by Configure to determine the full
8408           pathname (if any) of the zip program.  After Configure runs, the
8409           value is reset to a plain "zip" and is not useful.
8410

GIT DATA

8412       Information on the git commit from which the current perl binary was
8413       compiled can be found in the variable $Config::Git_Data.  The variable
8414       is a structured string that looks something like this:
8415
8416         git_commit_id='ea0c2dbd5f5ac6845ecc7ec6696415bf8e27bd52'
8417         git_describe='GitLive-blead-1076-gea0c2db'
8418         git_branch='smartmatch'
8419         git_uncommitted_changes=''
8420         git_commit_id_title='Commit id:'
8421         git_commit_date='2009-05-09 17:47:31 +0200'
8422
8423       Its format is not guaranteed not to change over time.
8424

NOTE

8426       This module contains a good example of how to use tie to implement a
8427       cache and an example of how to make a tied variable readonly to those
8428       outside of it.
8429
8430
8431
8432perl v5.32.1                      2021-03-31                       Config(3pm)
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