1PERLVMS(1) Perl Programmers Reference Guide PERLVMS(1)
2
6 perlvms - VMS-specific documentation for Perl
7
9 Gathered below are notes describing details of Perl 5's behavior on
10 VMS. They are a supplement to the regular Perl 5 documentation, so we
11 have focussed on the ways in which Perl 5 functions differently under
12 VMS than it does under Unix, and on the interactions between Perl and
13 the rest of the operating system. We haven't tried to duplicate
14 complete descriptions of Perl features from the main Perl
15 documentation, which can be found in the [.pod] subdirectory of the
16 Perl distribution.
17 We hope these notes will save you from confusion and lost sleep when
19 writing Perl scripts on VMS. If you find we've missed something you
20 think should appear here, please don't hesitate to drop a line to
21 vmsperl@perl.org.
22
24 Directions for building and installing Perl 5 can be found in the file
25 README.vms in the main source directory of the Perl distribution..
26
28 Core Images
29 During the installation process, three Perl images are produced.
30 Miniperl.Exe is an executable image which contains all of the basic
31 functionality of Perl, but cannot take advantage of Perl extensions.
32 It is used to generate several files needed to build the complete Perl
33 and various extensions. Once you've finished installing Perl, you can
34 delete this image.
35 Most of the complete Perl resides in the shareable image PerlShr.Exe,
37 which provides a core to which the Perl executable image and all Perl
38 extensions are linked. You should place this image in Sys$Share, or
39 define the logical name PerlShr to translate to the full file
40 specification of this image. It should be world readable. (Remember
41 that if a user has execute only access to PerlShr, VMS will treat it as
42 if it were a privileged shareable image, and will therefore require all
43 downstream shareable images to be INSTALLed, etc.)
44 Finally, Perl.Exe is an executable image containing the main entry
46 point for Perl, as well as some initialization code. It should be
47 placed in a public directory, and made world executable. In order to
48 run Perl with command line arguments, you should define a foreign
49 command to invoke this image.
50 Perl Extensions
52 Perl extensions are packages which provide both XS and Perl code to add
53 new functionality to perl. (XS is a meta-language which simplifies
54 writing C code which interacts with Perl, see perlxs for more details.)
55 The Perl code for an extension is treated like any other library module
56 - it's made available in your script through the appropriate "use" or
57 "require" statement, and usually defines a Perl package containing the
58 extension.
59 The portion of the extension provided by the XS code may be connected
61 to the rest of Perl in either of two ways. In the static
62 configuration, the object code for the extension is linked directly
63 into PerlShr.Exe, and is initialized whenever Perl is invoked. In the
64 dynamic configuration, the extension's machine code is placed into a
65 separate shareable image, which is mapped by Perl's DynaLoader when the
66 extension is "use"d or "require"d in your script. This allows you to
67 maintain the extension as a separate entity, at the cost of keeping
68 track of the additional shareable image. Most extensions can be set up
69 as either static or dynamic.
70 The source code for an extension usually resides in its own directory.
72 At least three files are generally provided: Extshortname.xs (where
73 Extshortname is the portion of the extension's name following the last
74 "::"), containing the XS code, Extshortname.pm, the Perl library module
75 for the extension, and Makefile.PL, a Perl script which uses the
76 "MakeMaker" library modules supplied with Perl to generate a
77 Descrip.MMS file for the extension.
78 Installing static extensions
80 Since static extensions are incorporated directly into PerlShr.Exe,
81 you'll have to rebuild Perl to incorporate a new extension. You should
82 edit the main Descrip.MMS or Makefile you use to build Perl, adding the
83 extension's name to the "ext" macro, and the extension's object file to
84 the "extobj" macro. You'll also need to build the extension's object
85 file, either by adding dependencies to the main Descrip.MMS, or using a
86 separate Descrip.MMS for the extension. Then, rebuild PerlShr.Exe to
87 incorporate the new code.
88 Finally, you'll need to copy the extension's Perl library module to the
90 [.Extname] subdirectory under one of the directories in @INC, where
91 Extname is the name of the extension, with all "::" replaced by "."
92 (e.g. the library module for extension Foo::Bar would be copied to a
93 [.Foo.Bar] subdirectory).
94 Installing dynamic extensions
96 In general, the distributed kit for a Perl extension includes a file
97 named Makefile.PL, which is a Perl program which is used to create a
98 Descrip.MMS file which can be used to build and install the files
99 required by the extension. The kit should be unpacked into a directory
100 tree not under the main Perl source directory, and the procedure for
101 building the extension is simply
102 $ perl Makefile.PL ! Create Descrip.MMS
104 $ mmk ! Build necessary files
105 $ mmk test ! Run test code, if supplied
106 $ mmk install ! Install into public Perl tree
107 N.B. The procedure by which extensions are built and tested creates
109 several levels (at least 4) under the directory in which the
110 extension's source files live. For this reason if you are running a
111 version of VMS prior to V7.1 you shouldn't nest the source directory
112 too deeply in your directory structure lest you exceed RMS' maximum of
113 8 levels of subdirectory in a filespec. (You can use rooted logical
114 names to get another 8 levels of nesting, if you can't place the files
115 near the top of the physical directory structure.)
116 VMS support for this process in the current release of Perl is
118 sufficient to handle most extensions. However, it does not yet
119 recognize extra libraries required to build shareable images which are
120 part of an extension, so these must be added to the linker options file
121 for the extension by hand. For instance, if the PGPLOT extension to
122 Perl requires the PGPLOTSHR.EXE shareable image in order to properly
123 link the Perl extension, then the line "PGPLOTSHR/Share" must be added
124 to the linker options file PGPLOT.Opt produced during the build process
125 for the Perl extension.
126 By default, the shareable image for an extension is placed in the
128 [.lib.site_perl.autoArch.Extname] directory of the installed Perl
129 directory tree (where Arch is VMS_VAX or VMS_AXP, and Extname is the
130 name of the extension, with each "::" translated to "."). (See the
131 MakeMaker documentation for more details on installation options for
132 extensions.) However, it can be manually placed in any of several
133 locations:
134 · the [.Lib.Auto.Arch$PVersExtname] subdirectory of one of the
136 directories in @INC (where PVers is the version of Perl you're
137 using, as supplied in $], with '.' converted to '_'), or
138 · one of the directories in @INC, or
140 · a directory which the extensions Perl library module passes to the
142 DynaLoader when asking it to map the shareable image, or
143 · Sys$Share or Sys$Library.
145 If the shareable image isn't in any of these places, you'll need to
147 define a logical name Extshortname, where Extshortname is the portion
148 of the extension's name after the last "::", which translates to the
149 full file specification of the shareable image.
150
152 Syntax
153 We have tried to make Perl aware of both VMS-style and Unix-style file
154 specifications wherever possible. You may use either style, or both,
155 on the command line and in scripts, but you may not combine the two
156 styles within a single file specification. VMS Perl interprets Unix
157 pathnames in much the same way as the CRTL (e.g. the first component of
158 an absolute path is read as the device name for the VMS file
159 specification). There are a set of functions provided in the
160 "VMS::Filespec" package for explicit interconversion between VMS and
161 Unix syntax; its documentation provides more details.
162 We've tried to minimize the dependence of Perl library modules on Unix
164 syntax, but you may find that some of these, as well as some scripts
165 written for Unix systems, will require that you use Unix syntax, since
166 they will assume that '/' is the directory separator, etc. If you find
167 instances of this in the Perl distribution itself, please let us know,
168 so we can try to work around them.
169 Also when working on Perl programs on VMS, if you need a syntax in a
171 specific operating system format, then you need either to check the
172 appropriate DECC$ feature logical, or call a conversion routine to
173 force it to that format.
174 The feature logical name DECC$FILENAME_UNIX_REPORT modifies traditional
176 Perl behavior in the conversion of file specifications from Unix to VMS
177 format in order to follow the extended character handling rules now
178 expected by the CRTL. Specifically, when this feature is in effect,
179 the "./.../" in a Unix path is now translated to "[.^.^.^.]" instead of
180 the traditional VMS "[...]". To be compatible with what MakeMaker
181 expects, if a VMS path cannot be translated to a Unix path, it is
182 passed through unchanged, so "unixify("[...]")" will return "[...]".
183 The handling of extended characters is largely complete in the VMS-
185 specific C infrastructure of Perl, but more work is still needed to
186 fully support extended syntax filenames in several core modules. In
187 particular, at this writing PathTools has only partial support for
188 directories containing some extended characters.
189 There are several ambiguous cases where a conversion routine cannot
191 determine whether an input filename is in Unix format or in VMS format,
192 since now both VMS and Unix file specifications may have characters in
193 them that could be mistaken for syntax delimiters of the other type. So
194 some pathnames simply cannot be used in a mode that allows either type
195 of pathname to be present. Perl will tend to assume that an ambiguous
196 filename is in Unix format.
197 Allowing "." as a version delimiter is simply incompatible with
199 determining whether a pathname is in VMS format or in Unix format with
200 extended file syntax. There is no way to know whether "perl-5.8.6" is
201 a Unix "perl-5.8.6" or a VMS "perl-5.8;6" when passing it to unixify()
202 or vmsify().
203 The DECC$FILENAME_UNIX_REPORT logical name controls how Perl interprets
205 filenames to the extent that Perl uses the CRTL internally for many
206 purposes, and attempts to follow CRTL conventions for reporting
207 filenames. The DECC$FILENAME_UNIX_ONLY feature differs in that it
208 expects all filenames passed to the C run-time to be already in Unix
209 format. This feature is not yet supported in Perl since Perl uses
210 traditional OpenVMS file specifications internally and in the test
211 harness, and it is not yet clear whether this mode will be useful or
212 useable. The feature logical name DECC$POSIX_COMPLIANT_PATHNAMES is
213 new with the RMS Symbolic Link SDK and included with OpenVMS v8.3, but
214 is not yet supported in Perl.
215 Filename Case
217 Perl follows VMS defaults and override settings in preserving (or not
218 preserving) filename case. Case is not preserved on ODS-2 formatted
219 volumes on any architecture. On ODS-5 volumes, filenames may be case
220 preserved depending on process and feature settings. Perl now honors
221 DECC$EFS_CASE_PRESERVE and DECC$ARGV_PARSE_STYLE on those systems where
222 the CRTL supports these features. When these features are not enabled
223 or the CRTL does not support them, Perl follows the traditional CRTL
224 behavior of downcasing command-line arguments and returning file
225 specifications in lower case only.
226 N. B. It is very easy to get tripped up using a mixture of other
228 programs, external utilities, and Perl scripts that are in varying
229 states of being able to handle case preservation. For example, a file
230 created by an older version of an archive utility or a build utility
231 such as MMK or MMS may generate a filename in all upper case even on an
232 ODS-5 volume. If this filename is later retrieved by a Perl script or
233 module in a case preserving environment, that upper case name may not
234 match the mixed-case or lower-case expections of the Perl code. Your
235 best bet is to follow an all-or-nothing approach to case preservation:
236 either don't use it at all, or make sure your entire toolchain and
237 application environment support and use it.
238 OpenVMS Alpha v7.3-1 and later and all version of OpenVMS I64 support
240 case sensitivity as a process setting (see "SET PROCESS
241 /CASE_LOOKUP=SENSITIVE"). Perl does not currently suppport case
242 sensitivity on VMS, but it may in the future, so Perl programs should
243 use the "File::Spec->case_tolerant" method to determine the state, and
244 not the $^O variable.
245 Symbolic Links
247 When built on an ODS-5 volume with symbolic links enabled, Perl by
248 default supports symbolic links when the requisite support is available
249 in the filesystem and CRTL (generally 64-bit OpenVMS v8.3 and later).
250 There are a number of limitations and caveats to be aware of when
251 working with symbolic links on VMS. Most notably, the target of a
252 valid symbolic link must be expressed as a Unix-style path and it must
253 exist on a volume visible from your POSIX root (see the "SHOW ROOT"
254 command in DCL help). For further details on symbolic link
255 capabilities and requirements, see chapter 12 of the CRTL manual that
256 ships with OpenVMS v8.3 or later.
257 Wildcard expansion
259 File specifications containing wildcards are allowed both on the
260 command line and within Perl globs (e.g. "<*.c>"). If the wildcard
261 filespec uses VMS syntax, the resultant filespecs will follow VMS
262 syntax; if a Unix-style filespec is passed in, Unix-style filespecs
263 will be returned. Similar to the behavior of wildcard globbing for a
264 Unix shell, one can escape command line wildcards with double quotation
265 marks """ around a perl program command line argument. However, owing
266 to the stripping of """ characters carried out by the C handling of
267 argv you will need to escape a construct such as this one (in a
268 directory containing the files PERL.C, PERL.EXE, PERL.H, and PERL.OBJ):
269 $ perl -e "print join(' ',@ARGV)" perl.*
271 perl.c perl.exe perl.h perl.obj
272 in the following triple quoted manner:
274 $ perl -e "print join(' ',@ARGV)" """perl.*"""
276 perl.*
277 In both the case of unquoted command line arguments or in calls to
279 "glob()" VMS wildcard expansion is performed. (csh-style wildcard
280 expansion is available if you use "File::Glob::glob".) If the wildcard
281 filespec contains a device or directory specification, then the
282 resultant filespecs will also contain a device and directory;
283 otherwise, device and directory information are removed. VMS-style
284 resultant filespecs will contain a full device and directory, while
285 Unix-style resultant filespecs will contain only as much of a directory
286 path as was present in the input filespec. For example, if your
287 default directory is Perl_Root:[000000], the expansion of "[.t]*.*"
288 will yield filespecs like "perl_root:[t]base.dir", while the expansion
289 of "t/*/*" will yield filespecs like "t/base.dir". (This is done to
290 match the behavior of glob expansion performed by Unix shells.)
291 Similarly, the resultant filespec will contain the file version only if
293 one was present in the input filespec.
294 Pipes
296 Input and output pipes to Perl filehandles are supported; the "file
297 name" is passed to lib$spawn() for asynchronous execution. You should
298 be careful to close any pipes you have opened in a Perl script, lest
299 you leave any "orphaned" subprocesses around when Perl exits.
300 You may also use backticks to invoke a DCL subprocess, whose output is
302 used as the return value of the expression. The string between the
303 backticks is handled as if it were the argument to the "system"
304 operator (see below). In this case, Perl will wait for the subprocess
305 to complete before continuing.
306 The mailbox (MBX) that perl can create to communicate with a pipe
308 defaults to a buffer size of 8192 on 64-bit systems, 512 on VAX. The
309 default buffer size is adjustable via the logical name PERL_MBX_SIZE
310 provided that the value falls between 128 and the SYSGEN parameter
311 MAXBUF inclusive. For example, to set the mailbox size to 32767 use
312 "$ENV{'PERL_MBX_SIZE'} = 32767;" and then open and use pipe constructs.
313 An alternative would be to issue the command:
314 $ Define PERL_MBX_SIZE 32767
316 before running your wide record pipe program. A larger value may
318 improve performance at the expense of the BYTLM UAF quota.
319
321 The PERL5LIB and PERLLIB logical names work as documented in perl,
322 except that the element separator is '|' instead of ':'. The directory
323 specifications may use either VMS or Unix syntax.
324
326 The Perl forked debugger places the debugger commands and output in a
327 separate X-11 terminal window so that commands and output from multiple
328 processes are not mixed together.
329 Perl on VMS supports an emulation of the forked debugger when Perl is
331 run on a VMS system that has X11 support installed.
332 To use the forked debugger, you need to have the default display set to
334 an X-11 Server and some environment variables set that Unix expects.
335 The forked debugger requires the environment variable "TERM" to be
337 "xterm", and the environment variable "DISPLAY" to exist. "xterm" must
338 be in lower case.
339 $define TERM "xterm"
341 $define DISPLAY "hostname:0.0"
343 Currently the value of "DISPLAY" is ignored. It is recommended that it
345 be set to be the hostname of the display, the server and screen in Unix
346 notation. In the future the value of DISPLAY may be honored by Perl
347 instead of using the default display.
348 It may be helpful to always use the forked debugger so that script I/O
350 is separated from debugger I/O. You can force the debugger to be
351 forked by assigning a value to the logical name <PERLDB_PIDS> that is
352 not a process identification number.
353 $define PERLDB_PIDS XXXX
355
357 The PERL_VMS_EXCEPTION_DEBUG being defined as "ENABLE" will cause the
358 VMS debugger to be invoked if a fatal exception that is not otherwise
359 handled is raised. The purpose of this is to allow debugging of
360 internal Perl problems that would cause such a condition.
361 This allows the programmer to look at the execution stack and variables
363 to find out the cause of the exception. As the debugger is being
364 invoked as the Perl interpreter is about to do a fatal exit, continuing
365 the execution in debug mode is usally not practical.
366 Starting Perl in the VMS debugger may change the program execution
368 profile in a way that such problems are not reproduced.
369 The "kill" function can be used to test this functionality from within
371 a program.
372 In typical VMS style, only the first letter of the value of this
374 logical name is actually checked in a case insensitive mode, and it is
375 considered enabled if it is the value "T","1" or "E".
376 This logical name must be defined before Perl is started.
378
380 I/O redirection and backgrounding
381 Perl for VMS supports redirection of input and output on the command
382 line, using a subset of Bourne shell syntax:
383 · "<file" reads stdin from "file",
385 · ">file" writes stdout to "file",
387 · ">>file" appends stdout to "file",
389 · "2>file" writes stderr to "file",
391 · "2>>file" appends stderr to "file", and
393 · "2>&1" redirects stderr to stdout.
395 In addition, output may be piped to a subprocess, using the character
397 '|'. Anything after this character on the command line is passed to a
398 subprocess for execution; the subprocess takes the output of Perl as
399 its input.
400 Finally, if the command line ends with '&', the entire command is run
402 in the background as an asynchronous subprocess.
403 Command line switches
405 The following command line switches behave differently under VMS than
406 described in perlrun. Note also that in order to pass uppercase
407 switches to Perl, you need to enclose them in double-quotes on the
408 command line, since the CRTL downcases all unquoted strings.
409 On newer 64 bit versions of OpenVMS, a process setting now controls if
411 the quoting is needed to preserve the case of command line arguments.
412 -i If the "-i" switch is present but no extension for a backup copy is
414 given, then inplace editing creates a new version of a file; the
415 existing copy is not deleted. (Note that if an extension is given,
416 an existing file is renamed to the backup file, as is the case
417 under other operating systems, so it does not remain as a previous
418 version under the original filename.)
419 -S If the "-S" or "-"S"" switch is present and the script name does
421 not contain a directory, then Perl translates the logical name
422 DCL$PATH as a searchlist, using each translation as a directory in
423 which to look for the script. In addition, if no file type is
424 specified, Perl looks in each directory for a file matching the
425 name specified, with a blank type, a type of .pl, and a type of
426 .com, in that order.
427 -u The "-u" switch causes the VMS debugger to be invoked after the
429 Perl program is compiled, but before it has run. It does not
430 create a core dump file.
431
433 As of the time this document was last revised, the following Perl
434 functions were implemented in the VMS port of Perl (functions marked
435 with * are discussed in more detail below):
436 file tests*, abs, alarm, atan, backticks*, binmode*, bless,
438 caller, chdir, chmod, chown, chomp, chop, chr,
439 close, closedir, cos, crypt*, defined, delete, die, do, dump*,
440 each, endgrent, endpwent, eof, eval, exec*, exists, exit, exp,
441 fileno, flock getc, getgrent*, getgrgid*, getgrnam, getlogin, getppid,
442 getpwent*, getpwnam*, getpwuid*, glob, gmtime*, goto,
443 grep, hex, ioctl, import, index, int, join, keys, kill*,
444 last, lc, lcfirst, lchown*, length, link*, local, localtime, log, lstat, m//,
445 map, mkdir, my, next, no, oct, open, opendir, ord, pack,
446 pipe, pop, pos, print, printf, push, q//, qq//, qw//,
447 qx//*, quotemeta, rand, read, readdir, readlink*, redo, ref, rename,
448 require, reset, return, reverse, rewinddir, rindex,
449 rmdir, s///, scalar, seek, seekdir, select(internal),
450 select (system call)*, setgrent, setpwent, shift, sin, sleep,
451 socketpair, sort, splice, split, sprintf, sqrt, srand, stat,
452 study, substr, symlink*, sysread, system*, syswrite, tell,
453 telldir, tie, time, times*, tr///, uc, ucfirst, umask,
454 undef, unlink*, unpack, untie, unshift, use, utime*,
455 values, vec, wait, waitpid*, wantarray, warn, write, y///
456 The following functions were not implemented in the VMS port, and
458 calling them produces a fatal error (usually) or undefined behavior
459 (rarely, we hope):
460 chroot, dbmclose, dbmopen, fork*, getpgrp, getpriority,
462 msgctl, msgget, msgsend, msgrcv, semctl,
463 semget, semop, setpgrp, setpriority, shmctl, shmget,
464 shmread, shmwrite, syscall
465 The following functions are available on Perls compiled with Dec C 5.2
467 or greater and running VMS 7.0 or greater:
468 truncate
470 The following functions are available on Perls built on VMS 7.2 or
472 greater:
473 fcntl (without locking)
475 The following functions may or may not be implemented, depending on
477 what type of socket support you've built into your copy of Perl:
478 accept, bind, connect, getpeername,
480 gethostbyname, getnetbyname, getprotobyname,
481 getservbyname, gethostbyaddr, getnetbyaddr,
482 getprotobynumber, getservbyport, gethostent,
483 getnetent, getprotoent, getservent, sethostent,
484 setnetent, setprotoent, setservent, endhostent,
485 endnetent, endprotoent, endservent, getsockname,
486 getsockopt, listen, recv, select(system call)*,
487 send, setsockopt, shutdown, socket
488 The following function is available on Perls built on 64 bit OpenVMS
490 v8.2 with hard links enabled on an ODS-5 formatted build disk. CRTL
491 support is in principle available as of OpenVMS v7.3-1, and better
492 configuration support could detect this.
493 link
495 The following functions are available on Perls built on 64 bit OpenVMS
497 v8.2 and later. CRTL support is in principle available as of OpenVMS
498 v7.3-2, and better configuration support could detect this.
499 getgrgid, getgrnam, getpwnam, getpwuid,
501 setgrent, ttyname
502 The following functions are available on Perls built on 64 bit OpenVMS
504 v8.2 and later.
505 statvfs, socketpair
507 File tests
509 The tests "-b", "-B", "-c", "-C", "-d", "-e", "-f", "-o", "-M",
510 "-s", "-S", "-t", "-T", and "-z" work as advertised. The return
511 values for "-r", "-w", and "-x" tell you whether you can actually
512 access the file; this may not reflect the UIC-based file
513 protections. Since real and effective UIC don't differ under VMS,
514 "-O", "-R", "-W", and "-X" are equivalent to "-o", "-r", "-w", and
515 "-x". Similarly, several other tests, including "-A", "-g", "-k",
516 "-l", "-p", and "-u", aren't particularly meaningful under VMS, and
517 the values returned by these tests reflect whatever your CRTL
518 "stat()" routine does to the equivalent bits in the st_mode field.
519 Finally, "-d" returns true if passed a device specification without
520 an explicit directory (e.g. "DUA1:"), as well as if passed a
521 directory.
522 There are DECC feature logical names AND ODS-5 volume attributes
524 that also control what values are returned for the date fields.
525 Note: Some sites have reported problems when using the file-access
527 tests ("-r", "-w", and "-x") on files accessed via DEC's DFS.
528 Specifically, since DFS does not currently provide access to the
529 extended file header of files on remote volumes, attempts to
530 examine the ACL fail, and the file tests will return false, with $!
531 indicating that the file does not exist. You can use "stat" on
532 these files, since that checks UIC-based protection only, and then
533 manually check the appropriate bits, as defined by your C
534 compiler's stat.h, in the mode value it returns, if you need an
535 approximation of the file's protections.
536 backticks
538 Backticks create a subprocess, and pass the enclosed string to it
539 for execution as a DCL command. Since the subprocess is created
540 directly via "lib$spawn()", any valid DCL command string may be
541 specified.
542 binmode FILEHANDLE
544 The "binmode" operator will attempt to insure that no translation
545 of carriage control occurs on input from or output to this
546 filehandle. Since this involves reopening the file and then
547 restoring its file position indicator, if this function returns
548 FALSE, the underlying filehandle may no longer point to an open
549 file, or may point to a different position in the file than before
550 "binmode" was called.
551 Note that "binmode" is generally not necessary when using normal
553 filehandles; it is provided so that you can control I/O to existing
554 record-structured files when necessary. You can also use the
555 "vmsfopen" function in the VMS::Stdio extension to gain finer
556 control of I/O to files and devices with different record
557 structures.
558 crypt PLAINTEXT, USER
560 The "crypt" operator uses the "sys$hash_password" system service to
561 generate the hashed representation of PLAINTEXT. If USER is a
562 valid username, the algorithm and salt values are taken from that
563 user's UAF record. If it is not, then the preferred algorithm and
564 a salt of 0 are used. The quadword encrypted value is returned as
565 an 8-character string.
566 The value returned by "crypt" may be compared against the encrypted
568 password from the UAF returned by the "getpw*" functions, in order
569 to authenticate users. If you're going to do this, remember that
570 the encrypted password in the UAF was generated using uppercase
571 username and password strings; you'll have to upcase the arguments
572 to "crypt" to insure that you'll get the proper value:
573 sub validate_passwd {
575 my($user,$passwd) = @_;
576 my($pwdhash);
577 if ( !($pwdhash = (getpwnam($user))[1]) ||
578 $pwdhash ne crypt("\U$passwd","\U$name") ) {
579 intruder_alert($name);
580 }
581 return 1;
582 }
583 die "die" will force the native VMS exit status to be an SS$_ABORT code
585 if neither of the $! or $? status values are ones that would cause
586 the native status to be interpreted as being what VMS classifies as
587 SEVERE_ERROR severity for DCL error handling.
588 When "PERL_VMS_POSIX_EXIT" is active (see "$?" below), the native
590 VMS exit status value will have either one of the $! or $? or $^E
591 or the Unix value 255 encoded into it in a way that the effective
592 original value can be decoded by other programs written in C,
593 including Perl and the GNV package. As per the normal non-VMS
594 behavior of "die" if either $! or $? are non-zero, one of those
595 values will be encoded into a native VMS status value. If both of
596 the Unix status values are 0, and the $^E value is set one of ERROR
597 or SEVERE_ERROR severity, then the $^E value will be used as the
598 exit code as is. If none of the above apply, the Unix value of 255
599 will be encoded into a native VMS exit status value.
600 Please note a significant difference in the behavior of "die" in
602 the "PERL_VMS_POSIX_EXIT" mode is that it does not force a VMS
603 SEVERE_ERROR status on exit. The Unix exit values of 2 through 255
604 will be encoded in VMS status values with severity levels of
605 SUCCESS. The Unix exit value of 1 will be encoded in a VMS status
606 value with a severity level of ERROR. This is to be compatible
607 with how the VMS C library encodes these values.
608 The minimum severity level set by "die" in "PERL_VMS_POSIX_EXIT"
610 mode may be changed to be ERROR or higher in the future depending
611 on the results of testing and further review.
612 See "$?" for a description of the encoding of the Unix value to
614 produce a native VMS status containing it.
615 dump
617 Rather than causing Perl to abort and dump core, the "dump"
618 operator invokes the VMS debugger. If you continue to execute the
619 Perl program under the debugger, control will be transferred to the
620 label specified as the argument to "dump", or, if no label was
621 specified, back to the beginning of the program. All other state
622 of the program (e.g. values of variables, open file handles) are
623 not affected by calling "dump".
624 exec LIST
626 A call to "exec" will cause Perl to exit, and to invoke the command
627 given as an argument to "exec" via "lib$do_command". If the
628 argument begins with '@' or '$' (other than as part of a filespec),
629 then it is executed as a DCL command. Otherwise, the first token
630 on the command line is treated as the filespec of an image to run,
631 and an attempt is made to invoke it (using .Exe and the process
632 defaults to expand the filespec) and pass the rest of "exec"'s
633 argument to it as parameters. If the token has no file type, and
634 matches a file with null type, then an attempt is made to determine
635 whether the file is an executable image which should be invoked
636 using "MCR" or a text file which should be passed to DCL as a
637 command procedure.
638 fork
640 While in principle the "fork" operator could be implemented via
641 (and with the same rather severe limitations as) the CRTL "vfork()"
642 routine, and while some internal support to do just that is in
643 place, the implementation has never been completed, making "fork"
644 currently unavailable. A true kernel "fork()" is expected in a
645 future version of VMS, and the pseudo-fork based on interpreter
646 threads may be available in a future version of Perl on VMS (see
647 perlfork). In the meantime, use "system", backticks, or piped
648 filehandles to create subprocesses.
649 getpwent
651 getpwnam
652 getpwuid
653 These operators obtain the information described in perlfunc, if
654 you have the privileges necessary to retrieve the named user's UAF
655 information via "sys$getuai". If not, then only the $name, $uid,
656 and $gid items are returned. The $dir item contains the login
657 directory in VMS syntax, while the $comment item contains the login
658 directory in Unix syntax. The $gcos item contains the owner field
659 from the UAF record. The $quota item is not used.
660 gmtime
662 The "gmtime" operator will function properly if you have a working
663 CRTL "gmtime()" routine, or if the logical name
664 SYS$TIMEZONE_DIFFERENTIAL is defined as the number of seconds which
665 must be added to UTC to yield local time. (This logical name is
666 defined automatically if you are running a version of VMS with
667 built-in UTC support.) If neither of these cases is true, a
668 warning message is printed, and "undef" is returned.
669 kill
671 In most cases, "kill" is implemented via the undocumented system
672 service $SIGPRC, which has the same calling sequence as $FORCEX,
673 but throws an exception in the target process rather than forcing
674 it to call $EXIT. Generally speaking, "kill" follows the behavior
675 of the CRTL's "kill()" function, but unlike that function can be
676 called from within a signal handler. Also, unlike the "kill" in
677 some versions of the CRTL, Perl's "kill" checks the validity of the
678 signal passed in and returns an error rather than attempting to
679 send an unrecognized signal.
680 Also, negative signal values don't do anything special under VMS;
682 they're just converted to the corresponding positive value.
683 qx//
685 See the entry on "backticks" above.
686 select (system call)
688 If Perl was not built with socket support, the system call version
689 of "select" is not available at all. If socket support is present,
690 then the system call version of "select" functions only for file
691 descriptors attached to sockets. It will not provide information
692 about regular files or pipes, since the CRTL "select()" routine
693 does not provide this functionality.
694 stat EXPR
696 Since VMS keeps track of files according to a different scheme than
697 Unix, it's not really possible to represent the file's ID in the
698 "st_dev" and "st_ino" fields of a "struct stat". Perl tries its
699 best, though, and the values it uses are pretty unlikely to be the
700 same for two different files. We can't guarantee this, though, so
701 caveat scriptor.
702 system LIST
704 The "system" operator creates a subprocess, and passes its
705 arguments to the subprocess for execution as a DCL command. Since
706 the subprocess is created directly via "lib$spawn()", any valid DCL
707 command string may be specified. If the string begins with '@', it
708 is treated as a DCL command unconditionally. Otherwise, if the
709 first token contains a character used as a delimiter in file
710 specification (e.g. ":" or "]"), an attempt is made to expand it
711 using a default type of .Exe and the process defaults, and if
712 successful, the resulting file is invoked via "MCR". This allows
713 you to invoke an image directly simply by passing the file
714 specification to "system", a common Unixish idiom. If the token
715 has no file type, and matches a file with null type, then an
716 attempt is made to determine whether the file is an executable
717 image which should be invoked using "MCR" or a text file which
718 should be passed to DCL as a command procedure.
719 If LIST consists of the empty string, "system" spawns an
721 interactive DCL subprocess, in the same fashion as typing SPAWN at
722 the DCL prompt.
723 Perl waits for the subprocess to complete before continuing
725 execution in the current process. As described in perlfunc, the
726 return value of "system" is a fake "status" which follows POSIX
727 semantics unless the pragma "use vmsish 'status'" is in effect; see
728 the description of $? in this document for more detail.
729 time
731 The value returned by "time" is the offset in seconds from
732 01-JAN-1970 00:00:00 (just like the CRTL's times() routine), in
733 order to make life easier for code coming in from the POSIX/Unix
734 world.
735 times
737 The array returned by the "times" operator is divided up according
738 to the same rules the CRTL "times()" routine. Therefore, the
739 "system time" elements will always be 0, since there is no
740 difference between "user time" and "system" time under VMS, and the
741 time accumulated by a subprocess may or may not appear separately
742 in the "child time" field, depending on whether times keeps track
743 of subprocesses separately. Note especially that the VAXCRTL (at
744 least) keeps track only of subprocesses spawned using fork and
745 exec; it will not accumulate the times of subprocesses spawned via
746 pipes, system, or backticks.
747 unlink LIST
749 "unlink" will delete the highest version of a file only; in order
750 to delete all versions, you need to say
751 1 while unlink LIST;
753 You may need to make this change to scripts written for a Unix
755 system which expect that after a call to "unlink", no files with
756 the names passed to "unlink" will exist. (Note: This can be
757 changed at compile time; if you "use Config" and
758 $Config{'d_unlink_all_versions'} is "define", then "unlink" will
759 delete all versions of a file on the first call.)
760 "unlink" will delete a file if at all possible, even if it requires
762 changing file protection (though it won't try to change the
763 protection of the parent directory). You can tell whether you've
764 got explicit delete access to a file by using the
765 "VMS::Filespec::candelete" operator. For instance, in order to
766 delete only files to which you have delete access, you could say
767 something like
768 sub safe_unlink {
770 my($file,$num);
771 foreach $file (@_) {
772 next unless VMS::Filespec::candelete($file);
773 $num += unlink $file;
774 }
775 $num;
776 }
777 (or you could just use "VMS::Stdio::remove", if you've installed
779 the VMS::Stdio extension distributed with Perl). If "unlink" has to
780 change the file protection to delete the file, and you interrupt it
781 in midstream, the file may be left intact, but with a changed ACL
782 allowing you delete access.
783 This behavior of "unlink" is to be compatible with POSIX behavior
785 and not traditional VMS behavior.
786 utime LIST
788 This operator changes only the modification time of the file (VMS
789 revision date) on ODS-2 volumes and ODS-5 volumes without access
790 dates enabled. On ODS-5 volumes with access dates enabled, the true
791 access time is modified.
792 waitpid PID,FLAGS
794 If PID is a subprocess started by a piped "open()" (see open),
795 "waitpid" will wait for that subprocess, and return its final
796 status value in $?. If PID is a subprocess created in some other
797 way (e.g. SPAWNed before Perl was invoked), "waitpid" will simply
798 check once per second whether the process has completed, and return
799 when it has. (If PID specifies a process that isn't a subprocess
800 of the current process, and you invoked Perl with the "-w" switch,
801 a warning will be issued.)
802 Returns PID on success, -1 on error. The FLAGS argument is ignored
804 in all cases.
805
807 The following VMS-specific information applies to the indicated
808 "special" Perl variables, in addition to the general information in
809 perlvar. Where there is a conflict, this information takes precedence.
810 %ENV
812 The operation of the %ENV array depends on the translation of the
813 logical name PERL_ENV_TABLES. If defined, it should be a search
814 list, each element of which specifies a location for %ENV elements.
815 If you tell Perl to read or set the element "$ENV{"name"}", then
816 Perl uses the translations of PERL_ENV_TABLES as follows:
817 CRTL_ENV
819 This string tells Perl to consult the CRTL's internal "environ"
820 array of key-value pairs, using name as the key. In most
821 cases, this contains only a few keys, but if Perl was invoked
822 via the C "exec[lv]e()" function, as is the case for CGI
823 processing by some HTTP servers, then the "environ" array may
824 have been populated by the calling program.
825 CLISYM_[LOCAL]
827 A string beginning with "CLISYM_"tells Perl to consult the
828 CLI's symbol tables, using name as the name of the symbol.
829 When reading an element of %ENV, the local symbol table is
830 scanned first, followed by the global symbol table.. The
831 characters following "CLISYM_" are significant when an element
832 of %ENV is set or deleted: if the complete string is
833 "CLISYM_LOCAL", the change is made in the local symbol table;
834 otherwise the global symbol table is changed.
835 Any other string
837 If an element of PERL_ENV_TABLES translates to any other
838 string, that string is used as the name of a logical name
839 table, which is consulted using name as the logical name. The
840 normal search order of access modes is used.
841 PERL_ENV_TABLES is translated once when Perl starts up; any changes
843 you make while Perl is running do not affect the behavior of %ENV.
844 If PERL_ENV_TABLES is not defined, then Perl defaults to consulting
845 first the logical name tables specified by LNM$FILE_DEV, and then
846 the CRTL "environ" array.
847 In all operations on %ENV, the key string is treated as if it were
849 entirely uppercase, regardless of the case actually specified in
850 the Perl expression.
851 When an element of %ENV is read, the locations to which
853 PERL_ENV_TABLES points are checked in order, and the value obtained
854 from the first successful lookup is returned. If the name of the
855 %ENV element contains a semi-colon, it and any characters after it
856 are removed. These are ignored when the CRTL "environ" array or a
857 CLI symbol table is consulted. However, the name is looked up in a
858 logical name table, the suffix after the semi-colon is treated as
859 the translation index to be used for the lookup. This lets you
860 look up successive values for search list logical names. For
861 instance, if you say
862 $ Define STORY once,upon,a,time,there,was
864 $ perl -e "for ($i = 0; $i <= 6; $i++) " -
865 _$ -e "{ print $ENV{'story;'.$i},' '}"
866 Perl will print "ONCE UPON A TIME THERE WAS", assuming, of course,
868 that PERL_ENV_TABLES is set up so that the logical name "story" is
869 found, rather than a CLI symbol or CRTL "environ" element with the
870 same name.
871 When an element of %ENV is set to a defined string, the
873 corresponding definition is made in the location to which the first
874 translation of PERL_ENV_TABLES points. If this causes a logical
875 name to be created, it is defined in supervisor mode. (The same is
876 done if an existing logical name was defined in executive or kernel
877 mode; an existing user or supervisor mode logical name is reset to
878 the new value.) If the value is an empty string, the logical
879 name's translation is defined as a single NUL (ASCII 00) character,
880 since a logical name cannot translate to a zero-length string.
881 (This restriction does not apply to CLI symbols or CRTL "environ"
882 values; they are set to the empty string.) An element of the CRTL
883 "environ" array can be set only if your copy of Perl knows about
884 the CRTL's "setenv()" function. (This is present only in some
885 versions of the DECCRTL; check $Config{d_setenv} to see whether
886 your copy of Perl was built with a CRTL that has this function.)
887 When an element of %ENV is set to "undef", the element is looked up
889 as if it were being read, and if it is found, it is deleted. (An
890 item "deleted" from the CRTL "environ" array is set to the empty
891 string; this can only be done if your copy of Perl knows about the
892 CRTL "setenv()" function.) Using "delete" to remove an element
893 from %ENV has a similar effect, but after the element is deleted,
894 another attempt is made to look up the element, so an inner-mode
895 logical name or a name in another location will replace the logical
896 name just deleted. In either case, only the first value found
897 searching PERL_ENV_TABLES is altered. It is not possible at
898 present to define a search list logical name via %ENV.
899 The element $ENV{DEFAULT} is special: when read, it returns Perl's
901 current default device and directory, and when set, it resets them,
902 regardless of the definition of PERL_ENV_TABLES. It cannot be
903 cleared or deleted; attempts to do so are silently ignored.
904 Note that if you want to pass on any elements of the C-local
906 environ array to a subprocess which isn't started by fork/exec, or
907 isn't running a C program, you can "promote" them to logical names
908 in the current process, which will then be inherited by all
909 subprocesses, by saying
910 foreach my $key (qw[C-local keys you want promoted]) {
912 my $temp = $ENV{$key}; # read from C-local array
913 $ENV{$key} = $temp; # and define as logical name
914 }
915 (You can't just say $ENV{$key} = $ENV{$key}, since the Perl
917 optimizer is smart enough to elide the expression.)
918 Don't try to clear %ENV by saying "%ENV = ();", it will throw a
920 fatal error. This is equivalent to doing the following from DCL:
921 DELETE/LOGICAL *
923 You can imagine how bad things would be if, for example, the
925 SYS$MANAGER or SYS$SYSTEM logical names were deleted.
926 At present, the first time you iterate over %ENV using "keys", or
928 "values", you will incur a time penalty as all logical names are
929 read, in order to fully populate %ENV. Subsequent iterations will
930 not reread logical names, so they won't be as slow, but they also
931 won't reflect any changes to logical name tables caused by other
932 programs.
933 You do need to be careful with the logical names representing
935 process-permanent files, such as "SYS$INPUT" and "SYS$OUTPUT". The
936 translations for these logical names are prepended with a two-byte
937 binary value (0x1B 0x00) that needs to be stripped off if you
938 wantto use it. (In previous versions of Perl it wasn't possible to
939 get the values of these logical names, as the null byte acted as an
940 end-of-string marker)
941 $! The string value of $! is that returned by the CRTL's strerror()
943 function, so it will include the VMS message for VMS-specific
944 errors. The numeric value of $! is the value of "errno", except if
945 errno is EVMSERR, in which case $! contains the value of
946 vaxc$errno. Setting $! always sets errno to the value specified.
947 If this value is EVMSERR, it also sets vaxc$errno to 4 (NONAME-F-
948 NOMSG), so that the string value of $! won't reflect the VMS error
949 message from before $! was set.
950 $^E This variable provides direct access to VMS status values in
952 vaxc$errno, which are often more specific than the generic Unix-
953 style error messages in $!. Its numeric value is the value of
954 vaxc$errno, and its string value is the corresponding VMS message
955 string, as retrieved by sys$getmsg(). Setting $^E sets vaxc$errno
956 to the value specified.
957 While Perl attempts to keep the vaxc$errno value to be current, if
959 errno is not EVMSERR, it may not be from the current operation.
960 $? The "status value" returned in $? is synthesized from the actual
962 exit status of the subprocess in a way that approximates POSIX
963 wait(5) semantics, in order to allow Perl programs to portably test
964 for successful completion of subprocesses. The low order 8 bits of
965 $? are always 0 under VMS, since the termination status of a
966 process may or may not have been generated by an exception.
967 The next 8 bits contain the termination status of the program.
969 If the child process follows the convention of C programs compiled
971 with the _POSIX_EXIT macro set, the status value will contain the
972 actual value of 0 to 255 returned by that program on a normal exit.
973 With the _POSIX_EXIT macro set, the Unix exit value of zero is
975 represented as a VMS native status of 1, and the Unix values from 2
976 to 255 are encoded by the equation:
977 VMS_status = 0x35a000 + (unix_value * 8) + 1.
979 And in the special case of Unix value 1 the encoding is:
981 VMS_status = 0x35a000 + 8 + 2 + 0x10000000.
983 For other termination statuses, the severity portion of the
985 subprocess's exit status is used: if the severity was success or
986 informational, these bits are all 0; if the severity was warning,
987 they contain a value of 1; if the severity was error or fatal
988 error, they contain the actual severity bits, which turns out to be
989 a value of 2 for error and 4 for severe_error. Fatal is another
990 term for the severe_error status.
991 As a result, $? will always be zero if the subprocess's exit status
993 indicated successful completion, and non-zero if a warning or error
994 occurred or a program compliant with encoding _POSIX_EXIT values
995 was run and set a status.
996 How can you tell the difference between a non-zero status that is
998 the result of a VMS native error status or an encoded Unix status?
999 You can not unless you look at the ${^CHILD_ERROR_NATIVE} value.
1000 The ${^CHILD_ERROR_NATIVE} value returns the actual VMS status
1001 value and check the severity bits. If the severity bits are equal
1002 to 1, then if the numeric value for $? is between 2 and 255 or 0,
1003 then $? accurately reflects a value passed back from a Unix
1004 application. If $? is 1, and the severity bits indicate a VMS
1005 error (2), then $? is from a Unix application exit value.
1006 In practice, Perl scripts that call programs that return
1008 _POSIX_EXIT type status values will be expecting those values, and
1009 programs that call traditional VMS programs will either be
1010 expecting the previous behavior or just checking for a non-zero
1011 status.
1012 And success is always the value 0 in all behaviors.
1014 When the actual VMS termination status of the child is an error,
1016 internally the $! value will be set to the closest Unix errno value
1017 to that error so that Perl scripts that test for error messages
1018 will see the expected Unix style error message instead of a VMS
1019 message.
1020 Conversely, when setting $? in an END block, an attempt is made to
1022 convert the POSIX value into a native status intelligible to the
1023 operating system upon exiting Perl. What this boils down to is
1024 that setting $? to zero results in the generic success value
1025 SS$_NORMAL, and setting $? to a non-zero value results in the
1026 generic failure status SS$_ABORT. See also "exit" in perlport.
1027 With the "PERL_VMS_POSIX_EXIT" logical name defined as "ENABLE",
1029 setting $? will cause the new value to be encoded into $^E so that
1030 either the original parent or child exit status values
1031 0 to 255 can be automatically recovered by C programs expecting
1032 _POSIX_EXIT behavior. If both a parent and a child exit value are
1033 non-zero, then it will be assumed that this is actually a VMS
1034 native status value to be passed through. The special value of
1035 0xFFFF is almost a NOOP as it will cause the current native VMS
1036 status in the C library to become the current native Perl VMS
1037 status, and is handled this way as it is known to not be a valid
1038 native VMS status value. It is recommend that only values in the
1039 range of normal Unix parent or child status numbers, 0 to 255 are
1040 used.
1041 The pragma "use vmsish 'status'" makes $? reflect the actual VMS
1043 exit status instead of the default emulation of POSIX status
1044 described above. This pragma also disables the conversion of non-
1045 zero values to SS$_ABORT when setting $? in an END block (but zero
1046 will still be converted to SS$_NORMAL).
1047 Do not use the pragma "use vmsish 'status'" with
1049 "PERL_VMS_POSIX_EXIT" enabled, as they are at times requesting
1050 conflicting actions and the consequence of ignoring this advice
1051 will be undefined to allow future improvements in the POSIX exit
1052 handling.
1053 In general, with "PERL_VMS_POSIX_EXIT" enabled, more detailed
1055 information will be availble in the exit status for DCL scripts or
1056 other native VMS tools, and will give the expected information for
1057 Posix programs. It has not been made the default in order to
1058 preserve backward compatibility.
1059 N.B. Setting "DECC$FILENAME_UNIX_REPORT" implicitly enables
1061 "PERL_VMS_POSIX_EXIT".
1062 $| Setting $| for an I/O stream causes data to be flushed all the way
1064 to disk on each write (i.e. not just to the underlying RMS buffers
1065 for a file). In other words, it's equivalent to calling fflush()
1066 and fsync() from C.
1067
1069 SDBM_File
1070 SDBM_File works properly on VMS. It has, however, one minor difference.
1071 The database directory file created has a .sdbm_dir extension rather
1072 than a .dir extension. .dir files are VMS filesystem directory files,
1073 and using them for other purposes could cause unacceptable problems.
1074
1076 Please see the git repository for revision history.
1077
1079 Charles Bailey bailey@cor.newman.upenn.edu Craig Berry
1080 craigberry@mac.com Dan Sugalski dan@sidhe.org John Malmberg
1081 wb8tyw@qsl.net
1082perl v5.12.4 2011-06-07 PERLVMS(1)