{ "content": [ { "type": "text", "text": "# PERLVMS (man)\n\n## NAME\n\nperlvms - VMS-specific documentation for Perl\n\n## DESCRIPTION\n\nGathered below are notes describing details of Perl 5's behavior on VMS. They are a\nsupplement to the regular Perl 5 documentation, so we have focussed on the ways in which Perl\n5 functions differently under VMS than it does under Unix, and on the interactions between\nPerl and the rest of the operating system. We haven't tried to duplicate complete\ndescriptions of Perl features from the main Perl documentation, which can be found in the\n[.pod] subdirectory of the Perl distribution.\n\n## Sections\n\n- **NAME**\n- **DESCRIPTION**\n- **Installation** (13 subsections)\n- **PERLVMSEXCEPTIONDEBUG** (7 subsections)\n- **AUTHOR**\n\nUse structuredContent.sections for detailed options, examples, and full documentation.\n" } ], "structuredContent": { "command": "PERLVMS", "section": "", "mode": "man", "summary": "perlvms - VMS-specific documentation for Perl", "synopsis": null, "tldr_summary": null, "tldr_examples": [], "tldr_source": null, "flags": [], "examples": [], "see_also": [], "section_outline": [ { "name": "NAME", "lines": 2, "subsections": [] }, { "name": "DESCRIPTION", "lines": 11, "subsections": [] }, { "name": "Installation", "lines": 3, "subsections": [ { "name": "Organization of Perl Images", "lines": 1 }, { "name": "Core Images", "lines": 18 }, { "name": "Perl Extensions", "lines": 21 }, { "name": "Installing static extensions", "lines": 12 }, { "name": "Installing dynamic extensions", "lines": 30 }, { "name": "File specifications", "lines": 1 }, { "name": "Syntax", "lines": 47 }, { "name": "Filename Case", "lines": 21 }, { "name": "Symbolic Links", "lines": 8 }, { "name": "Wildcard expansion", "lines": 32 }, { "name": "Pipes", "lines": 20 }, { "name": "PERL5LIB and PERLLIB", "lines": 5 }, { "name": "The Perl Forked Debugger", "lines": 26 } ] }, { "name": "PERLVMSEXCEPTIONDEBUG", "lines": 19, "subsections": [ { "name": "Command line", "lines": 1 }, { "name": "I/O redirection and backgrounding", "lines": 22 }, { "name": "Command line switches", "lines": 22 }, { "name": "Perl functions", "lines": 318 }, { "name": "Perl variables", "lines": 215 }, { "name": "Standard modules with VMS-specific differences", "lines": 6 }, { "name": "Revision date", "lines": 2 } ] }, { "name": "AUTHOR", "lines": 6, "subsections": [] } ], "sections": { "NAME": { "content": "perlvms - VMS-specific documentation for Perl\n", "subsections": [] }, "DESCRIPTION": { "content": "Gathered below are notes describing details of Perl 5's behavior on VMS. They are a\nsupplement to the regular Perl 5 documentation, so we have focussed on the ways in which Perl\n5 functions differently under VMS than it does under Unix, and on the interactions between\nPerl and the rest of the operating system. We haven't tried to duplicate complete\ndescriptions of Perl features from the main Perl documentation, which can be found in the\n[.pod] subdirectory of the Perl distribution.\n\nWe hope these notes will save you from confusion and lost sleep when writing Perl scripts on\nVMS. If you find we've missed something you think should appear here, please don't hesitate\nto drop a line to vmsperl@perl.org.\n", "subsections": [] }, "Installation": { "content": "Directions for building and installing Perl 5 can be found in the file README.vms in the main\nsource directory of the Perl distribution.\n", "subsections": [ { "name": "Organization of Perl Images", "content": "" }, { "name": "Core Images", "content": "During the build process, three Perl images are produced. Miniperl.Exe is an executable\nimage which contains all of the basic functionality of Perl, but cannot take advantage of\nPerl XS extensions and has a hard-wired list of library locations for loading pure-Perl\nmodules. It is used extensively to build and test Perl and various extensions, but is not\ninstalled.\n\nMost of the complete Perl resides in the shareable image PerlShr.Exe, which provides a core\nto which the Perl executable image and all Perl extensions are linked. It is generally\nlocated via the logical name PERLSHR. While it's possible to put the image in SYS$SHARE to\nmake it loadable, that's not recommended. And while you may wish to INSTALL the image for\nperformance reasons, you should not install it with privileges; if you do, the result will\nnot be what you expect as image privileges are disabled during Perl start-up.\n\nFinally, Perl.Exe is an executable image containing the main entry point for Perl, as well as\nsome initialization code. It should be placed in a public directory, and made world\nexecutable. In order to run Perl with command line arguments, you should define a foreign\ncommand to invoke this image.\n" }, { "name": "Perl Extensions", "content": "Perl extensions are packages which provide both XS and Perl code to add new functionality to\nperl. (XS is a meta-language which simplifies writing C code which interacts with Perl, see\nperlxs for more details.) The Perl code for an extension is treated like any other library\nmodule - it's made available in your script through the appropriate \"use\" or \"require\"\nstatement, and usually defines a Perl package containing the extension.\n\nThe portion of the extension provided by the XS code may be connected to the rest of Perl in\neither of two ways. In the static configuration, the object code for the extension is linked\ndirectly into PerlShr.Exe, and is initialized whenever Perl is invoked. In the dynamic\nconfiguration, the extension's machine code is placed into a separate shareable image, which\nis mapped by Perl's DynaLoader when the extension is \"use\"d or \"require\"d in your script.\nThis allows you to maintain the extension as a separate entity, at the cost of keeping track\nof the additional shareable image. Most extensions can be set up as either static or\ndynamic.\n\nThe source code for an extension usually resides in its own directory. At least three files\nare generally provided: Extshortname.xs (where Extshortname is the portion of the extension's\nname following the last \"::\"), containing the XS code, Extshortname.pm, the Perl library\nmodule for the extension, and Makefile.PL, a Perl script which uses the \"MakeMaker\" library\nmodules supplied with Perl to generate a Descrip.MMS file for the extension.\n" }, { "name": "Installing static extensions", "content": "Since static extensions are incorporated directly into PerlShr.Exe, you'll have to rebuild\nPerl to incorporate a new extension. You should edit the main Descrip.MMS or Makefile you\nuse to build Perl, adding the extension's name to the \"ext\" macro, and the extension's object\nfile to the \"extobj\" macro. You'll also need to build the extension's object file, either by\nadding dependencies to the main Descrip.MMS, or using a separate Descrip.MMS for the\nextension. Then, rebuild PerlShr.Exe to incorporate the new code.\n\nFinally, you'll need to copy the extension's Perl library module to the [.Extname]\nsubdirectory under one of the directories in @INC, where Extname is the name of the\nextension, with all \"::\" replaced by \".\" (e.g. the library module for extension Foo::Bar\nwould be copied to a [.Foo.Bar] subdirectory).\n" }, { "name": "Installing dynamic extensions", "content": "In general, the distributed kit for a Perl extension includes a file named Makefile.PL, which\nis a Perl program which is used to create a Descrip.MMS file which can be used to build and\ninstall the files required by the extension. The kit should be unpacked into a directory\ntree not under the main Perl source directory, and the procedure for building the extension\nis simply\n\n$ perl Makefile.PL ! Create Descrip.MMS\n$ mmk ! Build necessary files\n$ mmk test ! Run test code, if supplied\n$ mmk install ! Install into public Perl tree\n\nVMS support for this process in the current release of Perl is sufficient to handle most\nextensions. (See the MakeMaker documentation for more details on installation options for\nextensions.)\n\n• the [.Lib.Auto.Arch$PVersExtname] subdirectory of one of the directories in @INC (where\nPVers is the version of Perl you're using, as supplied in $], with '.' converted to ''),\nor\n\n• one of the directories in @INC, or\n\n• a directory which the extensions Perl library module passes to the DynaLoader when asking\nit to map the shareable image, or\n\n• Sys$Share or Sys$Library.\n\nIf the shareable image isn't in any of these places, you'll need to define a logical name\nExtshortname, where Extshortname is the portion of the extension's name after the last \"::\",\nwhich translates to the full file specification of the shareable image.\n" }, { "name": "File specifications", "content": "" }, { "name": "Syntax", "content": "We have tried to make Perl aware of both VMS-style and Unix-style file specifications\nwherever possible. You may use either style, or both, on the command line and in scripts,\nbut you may not combine the two styles within a single file specification. VMS Perl\ninterprets Unix pathnames in much the same way as the CRTL (e.g. the first component of an\nabsolute path is read as the device name for the VMS file specification). There are a set of\nfunctions provided in the \"VMS::Filespec\" package for explicit interconversion between VMS\nand Unix syntax; its documentation provides more details.\n\nWe've tried to minimize the dependence of Perl library modules on Unix syntax, but you may\nfind that some of these, as well as some scripts written for Unix systems, will require that\nyou use Unix syntax, since they will assume that '/' is the directory separator, etc. If you\nfind instances of this in the Perl distribution itself, please let us know, so we can try to\nwork around them.\n\nAlso when working on Perl programs on VMS, if you need a syntax in a specific operating\nsystem format, then you need either to check the appropriate DECC$ feature logical, or call a\nconversion routine to force it to that format.\n\nThe feature logical name DECC$FILENAMEUNIXREPORT modifies traditional Perl behavior in the\nconversion of file specifications from Unix to VMS format in order to follow the extended\ncharacter handling rules now expected by the CRTL. Specifically, when this feature is in\neffect, the \"./.../\" in a Unix path is now translated to \"[.^.^.^.]\" instead of the\ntraditional VMS \"[...]\". To be compatible with what MakeMaker expects, if a VMS path cannot\nbe translated to a Unix path, it is passed through unchanged, so \"unixify(\"[...]\")\" will\nreturn \"[...]\".\n\nThere are several ambiguous cases where a conversion routine cannot determine whether an\ninput filename is in Unix format or in VMS format, since now both VMS and Unix file\nspecifications may have characters in them that could be mistaken for syntax delimiters of\nthe other type. So some pathnames simply cannot be used in a mode that allows either type of\npathname to be present. Perl will tend to assume that an ambiguous filename is in Unix\nformat.\n\nAllowing \".\" as a version delimiter is simply incompatible with determining whether a\npathname is in VMS format or in Unix format with extended file syntax. There is no way to\nknow whether \"perl-5.8.6\" is a Unix \"perl-5.8.6\" or a VMS \"perl-5.8;6\" when passing it to\nunixify() or vmsify().\n\nThe DECC$FILENAMEUNIXREPORT logical name controls how Perl interprets filenames to the\nextent that Perl uses the CRTL internally for many purposes, and attempts to follow CRTL\nconventions for reporting filenames. The DECC$FILENAMEUNIXONLY feature differs in that it\nexpects all filenames passed to the C run-time to be already in Unix format. This feature is\nnot yet supported in Perl since Perl uses traditional OpenVMS file specifications internally\nand in the test harness, and it is not yet clear whether this mode will be useful or useable.\nThe feature logical name DECC$POSIXCOMPLIANTPATHNAMES is new with the RMS Symbolic Link SDK\nand included with OpenVMS v8.3, but is not yet supported in Perl.\n" }, { "name": "Filename Case", "content": "Perl enables DECC$EFSCASEPRESERVE and DECC$ARGVPARSESTYLE by default. Note that the\nlatter only takes effect when extended parse is set in the process in which Perl is running.\nWhen these features are explicitly disabled in the environment or the CRTL does not support\nthem, Perl follows the traditional CRTL behavior of downcasing command-line arguments and\nreturning file specifications in lower case only.\n\nN. B. It is very easy to get tripped up using a mixture of other programs, external\nutilities, and Perl scripts that are in varying states of being able to handle case\npreservation. For example, a file created by an older version of an archive utility or a\nbuild utility such as MMK or MMS may generate a filename in all upper case even on an ODS-5\nvolume. If this filename is later retrieved by a Perl script or module in a case preserving\nenvironment, that upper case name may not match the mixed-case or lower-case expectations of\nthe Perl code. Your best bet is to follow an all-or-nothing approach to case preservation:\neither don't use it at all, or make sure your entire toolchain and application environment\nsupport and use it.\n\nOpenVMS Alpha v7.3-1 and later and all version of OpenVMS I64 support case sensitivity as a\nprocess setting (see \"SET PROCESS /CASELOOKUP=SENSITIVE\"). Perl does not currently support\ncase sensitivity on VMS, but it may in the future, so Perl programs should use the\n\"File::Spec->casetolerant\" method to determine the state, and not the $^O variable.\n" }, { "name": "Symbolic Links", "content": "When built on an ODS-5 volume with symbolic links enabled, Perl by default supports symbolic\nlinks when the requisite support is available in the filesystem and CRTL (generally 64-bit\nOpenVMS v8.3 and later). There are a number of limitations and caveats to be aware of when\nworking with symbolic links on VMS. Most notably, the target of a valid symbolic link must\nbe expressed as a Unix-style path and it must exist on a volume visible from your POSIX root\n(see the \"SHOW ROOT\" command in DCL help). For further details on symbolic link capabilities\nand requirements, see chapter 12 of the CRTL manual that ships with OpenVMS v8.3 or later.\n" }, { "name": "Wildcard expansion", "content": "File specifications containing wildcards are allowed both on the command line and within Perl\nglobs (e.g. \"<*.c>\"). If the wildcard filespec uses VMS syntax, the resultant filespecs will\nfollow VMS syntax; if a Unix-style filespec is passed in, Unix-style filespecs will be\nreturned. Similar to the behavior of wildcard globbing for a Unix shell, one can escape\ncommand line wildcards with double quotation marks \"\"\" around a perl program command line\nargument. However, owing to the stripping of \"\"\" characters carried out by the C handling of\nargv you will need to escape a construct such as this one (in a directory containing the\nfiles PERL.C, PERL.EXE, PERL.H, and PERL.OBJ):\n\n$ perl -e \"print join(' ',@ARGV)\" perl.*\nperl.c perl.exe perl.h perl.obj\n\nin the following triple quoted manner:\n\n$ perl -e \"print join(' ',@ARGV)\" \"\"\"perl.*\"\"\"\nperl.*\n\nIn both the case of unquoted command line arguments or in calls to \"glob()\" VMS wildcard\nexpansion is performed. (csh-style wildcard expansion is available if you use\n\"File::Glob::glob\".) If the wildcard filespec contains a device or directory specification,\nthen the resultant filespecs will also contain a device and directory; otherwise, device and\ndirectory information are removed. VMS-style resultant filespecs will contain a full device\nand directory, while Unix-style resultant filespecs will contain only as much of a directory\npath as was present in the input filespec. For example, if your default directory is\nPerlRoot:[000000], the expansion of \"[.t]*.*\" will yield filespecs like\n\"perlroot:[t]base.dir\", while the expansion of \"t/*/*\" will yield filespecs like\n\"t/base.dir\". (This is done to match the behavior of glob expansion performed by Unix\nshells.)\n\nSimilarly, the resultant filespec will contain the file version only if one was present in\nthe input filespec.\n" }, { "name": "Pipes", "content": "Input and output pipes to Perl filehandles are supported; the \"file name\" is passed to\nlib$spawn() for asynchronous execution. You should be careful to close any pipes you have\nopened in a Perl script, lest you leave any \"orphaned\" subprocesses around when Perl exits.\n\nYou may also use backticks to invoke a DCL subprocess, whose output is used as the return\nvalue of the expression. The string between the backticks is handled as if it were the\nargument to the \"system\" operator (see below). In this case, Perl will wait for the\nsubprocess to complete before continuing.\n\nThe mailbox (MBX) that perl can create to communicate with a pipe defaults to a buffer size\nof 8192 on 64-bit systems, 512 on VAX. The default buffer size is adjustable via the logical\nname PERLMBXSIZE provided that the value falls between 128 and the SYSGEN parameter MAXBUF\ninclusive. For example, to set the mailbox size to 32767 use \"$ENV{'PERLMBXSIZE'} =\n32767;\" and then open and use pipe constructs. An alternative would be to issue the command:\n\n$ Define PERLMBXSIZE 32767\n\nbefore running your wide record pipe program. A larger value may improve performance at the\nexpense of the BYTLM UAF quota.\n" }, { "name": "PERL5LIB and PERLLIB", "content": "The PERL5LIB and PERLLIB environment elements work as documented in perl, except that the\nelement separator is, by default, '|' instead of ':'. However, when running under a Unix\nshell as determined by the logical name \"GNV$UNIXSHELL\", the separator will be ':' as on\nUnix systems. The directory specifications may use either VMS or Unix syntax.\n" }, { "name": "The Perl Forked Debugger", "content": "The Perl forked debugger places the debugger commands and output in a separate X-11 terminal\nwindow so that commands and output from multiple processes are not mixed together.\n\nPerl on VMS supports an emulation of the forked debugger when Perl is run on a VMS system\nthat has X11 support installed.\n\nTo use the forked debugger, you need to have the default display set to an X-11 Server and\nsome environment variables set that Unix expects.\n\nThe forked debugger requires the environment variable \"TERM\" to be \"xterm\", and the\nenvironment variable \"DISPLAY\" to exist. \"xterm\" must be in lower case.\n\n$define TERM \"xterm\"\n\n$define DISPLAY \"hostname:0.0\"\n\nCurrently the value of \"DISPLAY\" is ignored. It is recommended that it be set to be the\nhostname of the display, the server and screen in Unix notation. In the future the value of\nDISPLAY may be honored by Perl instead of using the default display.\n\nIt may be helpful to always use the forked debugger so that script I/O is separated from\ndebugger I/O. You can force the debugger to be forked by assigning a value to the logical\nname that is not a process identification number.\n\n$define PERLDBPIDS XXXX\n" } ] }, "PERLVMSEXCEPTIONDEBUG": { "content": "The PERLVMSEXCEPTIONDEBUG being defined as \"ENABLE\" will cause the VMS debugger to be\ninvoked if a fatal exception that is not otherwise handled is raised. The purpose of this is\nto allow debugging of internal Perl problems that would cause such a condition.\n\nThis allows the programmer to look at the execution stack and variables to find out the cause\nof the exception. As the debugger is being invoked as the Perl interpreter is about to do a\nfatal exit, continuing the execution in debug mode is usually not practical.\n\nStarting Perl in the VMS debugger may change the program execution profile in a way that such\nproblems are not reproduced.\n\nThe \"kill\" function can be used to test this functionality from within a program.\n\nIn typical VMS style, only the first letter of the value of this logical name is actually\nchecked in a case insensitive mode, and it is considered enabled if it is the value \"T\",\"1\"\nor \"E\".\n\nThis logical name must be defined before Perl is started.\n", "subsections": [ { "name": "Command line", "content": "" }, { "name": "I/O redirection and backgrounding", "content": "Perl for VMS supports redirection of input and output on the command line, using a subset of\nBourne shell syntax:\n\n• \"file\" writes stdout to \"file\",\n\n• \">>file\" appends stdout to \"file\",\n\n• \"2>file\" writes stderr to \"file\",\n\n• \"2>>file\" appends stderr to \"file\", and\n\n• \"2>&1\" redirects stderr to stdout.\n\nIn addition, output may be piped to a subprocess, using the character '|'. Anything after\nthis character on the command line is passed to a subprocess for execution; the subprocess\ntakes the output of Perl as its input.\n\nFinally, if the command line ends with '&', the entire command is run in the background as an\nasynchronous subprocess.\n" }, { "name": "Command line switches", "content": "The following command line switches behave differently under VMS than described in perlrun.\nNote also that in order to pass uppercase switches to Perl, you need to enclose them in\ndouble-quotes on the command line, since the CRTL downcases all unquoted strings.\n\nOn newer 64 bit versions of OpenVMS, a process setting now controls if the quoting is needed\nto preserve the case of command line arguments.\n\n-i If the \"-i\" switch is present but no extension for a backup copy is given, then inplace\nediting creates a new version of a file; the existing copy is not deleted. (Note that if\nan extension is given, an existing file is renamed to the backup file, as is the case\nunder other operating systems, so it does not remain as a previous version under the\noriginal filename.)\n\n-S If the \"-S\" or \"-\"S\"\" switch is present and the script name does not contain a directory,\nthen Perl translates the logical name DCL$PATH as a searchlist, using each translation as\na directory in which to look for the script. In addition, if no file type is specified,\nPerl looks in each directory for a file matching the name specified, with a blank type, a\ntype of .pl, and a type of .com, in that order.\n\n-u The \"-u\" switch causes the VMS debugger to be invoked after the Perl program is compiled,\nbut before it has run. It does not create a core dump file.\n" }, { "name": "Perl functions", "content": "As of the time this document was last revised, the following Perl functions were implemented\nin the VMS port of Perl (functions marked with * are discussed in more detail below):\n\nfile tests*, abs, alarm, atan, backticks*, binmode*, bless,\ncaller, chdir, chmod, chown, chomp, chop, chr,\nclose, closedir, cos, crypt*, defined, delete, die, do, dump*,\neach, endgrent, endpwent, eof, eval, exec*, exists, exit, exp,\nfileno, flock getc, getgrent*, getgrgid*, getgrnam, getlogin,\ngetppid, getpwent*, getpwnam*, getpwuid*, glob, gmtime*, goto,\ngrep, hex, ioctl, import, index, int, join, keys, kill*,\nlast, lc, lcfirst, lchown*, length, link*, local, localtime, log,\nlstat, m//, map, mkdir, my, next, no, oct, open, opendir, ord,\npack, pipe, pop, pos, print, printf, push, q//, qq//, qw//,\nqx//*, quotemeta, rand, read, readdir, readlink*, redo, ref,\nrename, require, reset, return, reverse, rewinddir, rindex,\nrmdir, s///, scalar, seek, seekdir, select(internal),\nselect (system call)*, setgrent, setpwent, shift, sin, sleep,\nsocketpair, sort, splice, split, sprintf, sqrt, srand, stat,\nstudy, substr, symlink*, sysread, system*, syswrite, tell,\ntelldir, tie, time, times*, tr///, uc, ucfirst, umask,\nundef, unlink*, unpack, untie, unshift, use, utime*,\nvalues, vec, wait, waitpid*, wantarray, warn, write, y///\n\nThe following functions were not implemented in the VMS port, and calling them produces a\nfatal error (usually) or undefined behavior (rarely, we hope):\n\nchroot, dbmclose, dbmopen, fork*, getpgrp, getpriority,\nmsgctl, msgget, msgsend, msgrcv, semctl,\nsemget, semop, setpgrp, setpriority, shmctl, shmget,\nshmread, shmwrite, syscall\n\nThe following functions are available on Perls compiled with Dec C 5.2 or greater and running\nVMS 7.0 or greater:\n\ntruncate\n\nThe following functions are available on Perls built on VMS 7.2 or greater:\n\nfcntl (without locking)\n\nThe following functions may or may not be implemented, depending on what type of socket\nsupport you've built into your copy of Perl:\n\naccept, bind, connect, getpeername,\ngethostbyname, getnetbyname, getprotobyname,\ngetservbyname, gethostbyaddr, getnetbyaddr,\ngetprotobynumber, getservbyport, gethostent,\ngetnetent, getprotoent, getservent, sethostent,\nsetnetent, setprotoent, setservent, endhostent,\nendnetent, endprotoent, endservent, getsockname,\ngetsockopt, listen, recv, select(system call)*,\nsend, setsockopt, shutdown, socket\n\nThe following function is available on Perls built on 64 bit OpenVMS v8.2 with hard links\nenabled on an ODS-5 formatted build disk. CRTL support is in principle available as of\nOpenVMS v7.3-1, and better configuration support could detect this.\n\nlink\n\nThe following functions are available on Perls built on 64 bit OpenVMS v8.2 and later. CRTL\nsupport is in principle available as of OpenVMS v7.3-2, and better configuration support\ncould detect this.\n\ngetgrgid, getgrnam, getpwnam, getpwuid,\nsetgrent, ttyname\n\nThe following functions are available on Perls built on 64 bit OpenVMS v8.2 and later.\n\nstatvfs, socketpair\n\nFile tests\nThe tests \"-b\", \"-B\", \"-c\", \"-C\", \"-d\", \"-e\", \"-f\", \"-o\", \"-M\", \"-s\", \"-S\", \"-t\", \"-T\",\nand \"-z\" work as advertised. The return values for \"-r\", \"-w\", and \"-x\" tell you whether\nyou can actually access the file; this may not reflect the UIC-based file protections.\nSince real and effective UIC don't differ under VMS, \"-O\", \"-R\", \"-W\", and \"-X\" are\nequivalent to \"-o\", \"-r\", \"-w\", and \"-x\". Similarly, several other tests, including\n\"-A\", \"-g\", \"-k\", \"-l\", \"-p\", and \"-u\", aren't particularly meaningful under VMS, and the\nvalues returned by these tests reflect whatever your CRTL \"stat()\" routine does to the\nequivalent bits in the stmode field. Finally, \"-d\" returns true if passed a device\nspecification without an explicit directory (e.g. \"DUA1:\"), as well as if passed a\ndirectory.\n\nThere are DECC feature logical names AND ODS-5 volume attributes that also control what\nvalues are returned for the date fields.\n\nNote: Some sites have reported problems when using the file-access tests (\"-r\", \"-w\", and\n\"-x\") on files accessed via DEC's DFS. Specifically, since DFS does not currently\nprovide access to the extended file header of files on remote volumes, attempts to\nexamine the ACL fail, and the file tests will return false, with $! indicating that the\nfile does not exist. You can use \"stat\" on these files, since that checks UIC-based\nprotection only, and then manually check the appropriate bits, as defined by your C\ncompiler's stat.h, in the mode value it returns, if you need an approximation of the\nfile's protections.\n\nbackticks\nBackticks create a subprocess, and pass the enclosed string to it for execution as a DCL\ncommand. Since the subprocess is created directly via \"lib$spawn()\", any valid DCL\ncommand string may be specified.\n\nbinmode FILEHANDLE\nThe \"binmode\" operator will attempt to insure that no translation of carriage control\noccurs on input from or output to this filehandle. Since this involves reopening the\nfile and then restoring its file position indicator, if this function returns FALSE, the\nunderlying filehandle may no longer point to an open file, or may point to a different\nposition in the file than before \"binmode\" was called.\n\nNote that \"binmode\" is generally not necessary when using normal filehandles; it is\nprovided so that you can control I/O to existing record-structured files when necessary.\nYou can also use the \"vmsfopen\" function in the VMS::Stdio extension to gain finer\ncontrol of I/O to files and devices with different record structures.\n\ncrypt PLAINTEXT, USER\nThe \"crypt\" operator uses the \"sys$hashpassword\" system service to generate the hashed\nrepresentation of PLAINTEXT. If USER is a valid username, the algorithm and salt values\nare taken from that user's UAF record. If it is not, then the preferred algorithm and a\nsalt of 0 are used. The quadword encrypted value is returned as an 8-character string.\n\nThe value returned by \"crypt\" may be compared against the encrypted password from the UAF\nreturned by the \"getpw*\" functions, in order to authenticate users. If you're going to\ndo this, remember that the encrypted password in the UAF was generated using uppercase\nusername and password strings; you'll have to upcase the arguments to \"crypt\" to insure\nthat you'll get the proper value:\n\nsub validatepasswd {\nmy($user,$passwd) = @;\nmy($pwdhash);\nif ( !($pwdhash = (getpwnam($user))[1]) ||\n$pwdhash ne crypt(\"\\U$passwd\",\"\\U$name\") ) {\nintruderalert($name);\n}\nreturn 1;\n}\n\ndie \"die\" will force the native VMS exit status to be an SS$ABORT code if neither of the $!\nor $? status values are ones that would cause the native status to be interpreted as\nbeing what VMS classifies as SEVEREERROR severity for DCL error handling.\n\nWhen \"PERLVMSPOSIXEXIT\" is active (see \"$?\" below), the native VMS exit status value\nwill have either one of the $! or $? or $^E or the Unix value 255 encoded into it in a\nway that the effective original value can be decoded by other programs written in C,\nincluding Perl and the GNV package. As per the normal non-VMS behavior of \"die\" if\neither $! or $? are non-zero, one of those values will be encoded into a native VMS\nstatus value. If both of the Unix status values are 0, and the $^E value is set one of\nERROR or SEVEREERROR severity, then the $^E value will be used as the exit code as is.\nIf none of the above apply, the Unix value of 255 will be encoded into a native VMS exit\nstatus value.\n\nPlease note a significant difference in the behavior of \"die\" in the\n\"PERLVMSPOSIXEXIT\" mode is that it does not force a VMS SEVEREERROR status on exit.\nThe Unix exit values of 2 through 255 will be encoded in VMS status values with severity\nlevels of SUCCESS. The Unix exit value of 1 will be encoded in a VMS status value with a\nseverity level of ERROR. This is to be compatible with how the VMS C library encodes\nthese values.\n\nThe minimum severity level set by \"die\" in \"PERLVMSPOSIXEXIT\" mode may be changed to\nbe ERROR or higher in the future depending on the results of testing and further review.\n\nSee \"$?\" for a description of the encoding of the Unix value to produce a native VMS\nstatus containing it.\n\ndump\nRather than causing Perl to abort and dump core, the \"dump\" operator invokes the VMS\ndebugger. If you continue to execute the Perl program under the debugger, control will\nbe transferred to the label specified as the argument to \"dump\", or, if no label was\nspecified, back to the beginning of the program. All other state of the program (e.g.\nvalues of variables, open file handles) are not affected by calling \"dump\".\n\nexec LIST\nA call to \"exec\" will cause Perl to exit, and to invoke the command given as an argument\nto \"exec\" via \"lib$docommand\". If the argument begins with '@' or '$' (other than as\npart of a filespec), then it is executed as a DCL command. Otherwise, the first token on\nthe command line is treated as the filespec of an image to run, and an attempt is made to\ninvoke it (using .Exe and the process defaults to expand the filespec) and pass the rest\nof \"exec\"'s argument to it as parameters. If the token has no file type, and matches a\nfile with null type, then an attempt is made to determine whether the file is an\nexecutable image which should be invoked using \"MCR\" or a text file which should be\npassed to DCL as a command procedure.\n\nfork\nWhile in principle the \"fork\" operator could be implemented via (and with the same rather\nsevere limitations as) the CRTL \"vfork()\" routine, and while some internal support to do\njust that is in place, the implementation has never been completed, making \"fork\"\ncurrently unavailable. A true kernel \"fork()\" is expected in a future version of VMS,\nand the pseudo-fork based on interpreter threads may be available in a future version of\nPerl on VMS (see perlfork). In the meantime, use \"system\", backticks, or piped\nfilehandles to create subprocesses.\n\ngetpwent\ngetpwnam\ngetpwuid\nThese operators obtain the information described in perlfunc, if you have the privileges\nnecessary to retrieve the named user's UAF information via \"sys$getuai\". If not, then\nonly the $name, $uid, and $gid items are returned. The $dir item contains the login\ndirectory in VMS syntax, while the $comment item contains the login directory in Unix\nsyntax. The $gcos item contains the owner field from the UAF record. The $quota item is\nnot used.\n\ngmtime\nThe \"gmtime\" operator will function properly if you have a working CRTL \"gmtime()\"\nroutine, or if the logical name SYS$TIMEZONEDIFFERENTIAL is defined as the number of\nseconds which must be added to UTC to yield local time. (This logical name is defined\nautomatically if you are running a version of VMS with built-in UTC support.) If neither\nof these cases is true, a warning message is printed, and \"undef\" is returned.\n\nkill\nIn most cases, \"kill\" is implemented via the undocumented system service $SIGPRC, which\nhas the same calling sequence as $FORCEX, but throws an exception in the target process\nrather than forcing it to call $EXIT. Generally speaking, \"kill\" follows the behavior of\nthe CRTL's \"kill()\" function, but unlike that function can be called from within a signal\nhandler. Also, unlike the \"kill\" in some versions of the CRTL, Perl's \"kill\" checks the\nvalidity of the signal passed in and returns an error rather than attempting to send an\nunrecognized signal.\n\nAlso, negative signal values don't do anything special under VMS; they're just converted\nto the corresponding positive value.\n\nqx//\nSee the entry on \"backticks\" above.\n\nselect (system call)\nIf Perl was not built with socket support, the system call version of \"select\" is not\navailable at all. If socket support is present, then the system call version of \"select\"\nfunctions only for file descriptors attached to sockets. It will not provide information\nabout regular files or pipes, since the CRTL \"select()\" routine does not provide this\nfunctionality.\n\nstat EXPR\nSince VMS keeps track of files according to a different scheme than Unix, it's not really\npossible to represent the file's ID in the \"stdev\" and \"stino\" fields of a \"struct\nstat\". Perl tries its best, though, and the values it uses are pretty unlikely to be the\nsame for two different files. We can't guarantee this, though, so caveat scriptor.\n\nsystem LIST\nThe \"system\" operator creates a subprocess, and passes its arguments to the subprocess\nfor execution as a DCL command. Since the subprocess is created directly via\n\"lib$spawn()\", any valid DCL command string may be specified. If the string begins with\n'@', it is treated as a DCL command unconditionally. Otherwise, if the first token\ncontains a character used as a delimiter in file specification (e.g. \":\" or \"]\"), an\nattempt is made to expand it using a default type of .Exe and the process defaults, and\nif successful, the resulting file is invoked via \"MCR\". This allows you to invoke an\nimage directly simply by passing the file specification to \"system\", a common Unixish\nidiom. If the token has no file type, and matches a file with null type, then an attempt\nis made to determine whether the file is an executable image which should be invoked\nusing \"MCR\" or a text file which should be passed to DCL as a command procedure.\n\nIf LIST consists of the empty string, \"system\" spawns an interactive DCL subprocess, in\nthe same fashion as typing SPAWN at the DCL prompt.\n\nPerl waits for the subprocess to complete before continuing execution in the current\nprocess. As described in perlfunc, the return value of \"system\" is a fake \"status\" which\nfollows POSIX semantics unless the pragma \"use vmsish 'status'\" is in effect; see the\ndescription of $? in this document for more detail.\n\ntime\nThe value returned by \"time\" is the offset in seconds from 01-JAN-1970 00:00:00 (just\nlike the CRTL's times() routine), in order to make life easier for code coming in from\nthe POSIX/Unix world.\n\ntimes\nThe array returned by the \"times\" operator is divided up according to the same rules the\nCRTL \"times()\" routine. Therefore, the \"system time\" elements will always be 0, since\nthere is no difference between \"user time\" and \"system\" time under VMS, and the time\naccumulated by a subprocess may or may not appear separately in the \"child time\" field,\ndepending on whether \"times()\" keeps track of subprocesses separately. Note especially\nthat the VAXCRTL (at least) keeps track only of subprocesses spawned using \"fork()\" and\n\"exec()\"; it will not accumulate the times of subprocesses spawned via pipes, \"system()\",\nor backticks.\n\nunlink LIST\n\"unlink\" will delete the highest version of a file only; in order to delete all versions,\nyou need to say\n\n1 while unlink LIST;\n\nYou may need to make this change to scripts written for a Unix system which expect that\nafter a call to \"unlink\", no files with the names passed to \"unlink\" will exist. (Note:\nThis can be changed at compile time; if you \"use Config\" and\n$Config{'dunlinkallversions'} is \"define\", then \"unlink\" will delete all versions of a\nfile on the first call.)\n\n\"unlink\" will delete a file if at all possible, even if it requires changing file\nprotection (though it won't try to change the protection of the parent directory). You\ncan tell whether you've got explicit delete access to a file by using the\n\"VMS::Filespec::candelete\" operator. For instance, in order to delete only files to\nwhich you have delete access, you could say something like\n\nsub safeunlink {\nmy($file,$num);\nforeach $file (@) {\nnext unless VMS::Filespec::candelete($file);\n$num += unlink $file;\n}\n$num;\n}\n\n(or you could just use \"VMS::Stdio::remove\", if you've installed the VMS::Stdio extension\ndistributed with Perl). If \"unlink\" has to change the file protection to delete the file,\nand you interrupt it in midstream, the file may be left intact, but with a changed ACL\nallowing you delete access.\n\nThis behavior of \"unlink\" is to be compatible with POSIX behavior and not traditional VMS\nbehavior.\n\nutime LIST\nThis operator changes only the modification time of the file (VMS revision date) on ODS-2\nvolumes and ODS-5 volumes without access dates enabled. On ODS-5 volumes with access\ndates enabled, the true access time is modified.\n\nwaitpid PID,FLAGS\nIf PID is a subprocess started by a piped \"open()\" (see open), \"waitpid\" will wait for\nthat subprocess, and return its final status value in $?. If PID is a subprocess created\nin some other way (e.g. SPAWNed before Perl was invoked), \"waitpid\" will simply check\nonce per second whether the process has completed, and return when it has. (If PID\nspecifies a process that isn't a subprocess of the current process, and you invoked Perl\nwith the \"-w\" switch, a warning will be issued.)\n\nReturns PID on success, -1 on error. The FLAGS argument is ignored in all cases.\n" }, { "name": "Perl variables", "content": "The following VMS-specific information applies to the indicated \"special\" Perl variables, in\naddition to the general information in perlvar. Where there is a conflict, this information\ntakes precedence.\n\n%ENV\nThe operation of the %ENV array depends on the translation of the logical name\nPERLENVTABLES. If defined, it should be a search list, each element of which specifies\na location for %ENV elements. If you tell Perl to read or set the element\n\"$ENV{\"name\"}\", then Perl uses the translations of PERLENVTABLES as follows:\n\nCRTLENV\nThis string tells Perl to consult the CRTL's internal \"environ\" array of key-value\npairs, using name as the key. In most cases, this contains only a few keys, but if\nPerl was invoked via the C \"exec[lv]e()\" function, as is the case for some embedded\nPerl applications or when running under a shell such as GNV bash, the \"environ\" array\nmay have been populated by the calling program.\n\nCLISYM[LOCAL]\nA string beginning with \"CLISYM\"tells Perl to consult the CLI's symbol tables, using\nname as the name of the symbol. When reading an element of %ENV, the local symbol\ntable is scanned first, followed by the global symbol table.. The characters\nfollowing \"CLISYM\" are significant when an element of %ENV is set or deleted: if the\ncomplete string is \"CLISYMLOCAL\", the change is made in the local symbol table;\notherwise the global symbol table is changed.\n\nAny other string\nIf an element of PERLENVTABLES translates to any other string, that string is used\nas the name of a logical name table, which is consulted using name as the logical\nname. The normal search order of access modes is used.\n\nPERLENVTABLES is translated once when Perl starts up; any changes you make while Perl\nis running do not affect the behavior of %ENV. If PERLENVTABLES is not defined, then\nPerl defaults to consulting first the logical name tables specified by LNM$FILEDEV, and\nthen the CRTL \"environ\" array. This default order is reversed when the logical name\nGNV$UNIXSHELL is defined, such as when running under GNV bash.\n\nFor operations on %ENV entries based on logical names or DCL symbols, the key string is\ntreated as if it were entirely uppercase, regardless of the case actually specified in\nthe Perl expression. Entries in %ENV based on the CRTL's environ array preserve the case\nof the key string when stored, and lookups are case sensitive.\n\nWhen an element of %ENV is read, the locations to which PERLENVTABLES points are\nchecked in order, and the value obtained from the first successful lookup is returned.\nIf the name of the %ENV element contains a semi-colon, it and any characters after it are\nremoved. These are ignored when the CRTL \"environ\" array or a CLI symbol table is\nconsulted. However, the name is looked up in a logical name table, the suffix after the\nsemi-colon is treated as the translation index to be used for the lookup. This lets you\nlook up successive values for search list logical names. For instance, if you say\n\n$ Define STORY once,upon,a,time,there,was\n$ perl -e \"for ($i = 0; $i <= 6; $i++) \" -\n$ -e \"{ print $ENV{'story;'.$i},' '}\"\n\nPerl will print \"ONCE UPON A TIME THERE WAS\", assuming, of course, that PERLENVTABLES\nis set up so that the logical name \"story\" is found, rather than a CLI symbol or CRTL\n\"environ\" element with the same name.\n\nWhen an element of %ENV is set to a defined string, the corresponding definition is made\nin the location to which the first translation of PERLENVTABLES points. If this causes\na logical name to be created, it is defined in supervisor mode. (The same is done if an\nexisting logical name was defined in executive or kernel mode; an existing user or\nsupervisor mode logical name is reset to the new value.) If the value is an empty\nstring, the logical name's translation is defined as a single \"NUL\" (ASCII \"\\0\")\ncharacter, since a logical name cannot translate to a zero-length string. (This\nrestriction does not apply to CLI symbols or CRTL \"environ\" values; they are set to the\nempty string.)\n\nWhen an element of %ENV is set to \"undef\", the element is looked up as if it were being\nread, and if it is found, it is deleted. (An item \"deleted\" from the CRTL \"environ\"\narray is set to the empty string.) Using \"delete\" to remove an element from %ENV has a\nsimilar effect, but after the element is deleted, another attempt is made to look up the\nelement, so an inner-mode logical name or a name in another location will replace the\nlogical name just deleted. In either case, only the first value found searching\nPERLENVTABLES is altered. It is not possible at present to define a search list\nlogical name via %ENV.\n\nThe element $ENV{DEFAULT} is special: when read, it returns Perl's current default device\nand directory, and when set, it resets them, regardless of the definition of\nPERLENVTABLES. It cannot be cleared or deleted; attempts to do so are silently\nignored.\n\nNote that if you want to pass on any elements of the C-local environ array to a\nsubprocess which isn't started by fork/exec, or isn't running a C program, you can\n\"promote\" them to logical names in the current process, which will then be inherited by\nall subprocesses, by saying\n\nforeach my $key (qw[C-local keys you want promoted]) {\nmy $temp = $ENV{$key}; # read from C-local array\n$ENV{$key} = $temp; # and define as logical name\n}\n\n(You can't just say $ENV{$key} = $ENV{$key}, since the Perl optimizer is smart enough to\nelide the expression.)\n\nDon't try to clear %ENV by saying \"%ENV = ();\", it will throw a fatal error. This is\nequivalent to doing the following from DCL:\n\nDELETE/LOGICAL *\n\nYou can imagine how bad things would be if, for example, the SYS$MANAGER or SYS$SYSTEM\nlogical names were deleted.\n\nAt present, the first time you iterate over %ENV using \"keys\", or \"values\", you will\nincur a time penalty as all logical names are read, in order to fully populate %ENV.\nSubsequent iterations will not reread logical names, so they won't be as slow, but they\nalso won't reflect any changes to logical name tables caused by other programs.\n\nYou do need to be careful with the logical names representing process-permanent files,\nsuch as \"SYS$INPUT\" and \"SYS$OUTPUT\". The translations for these logical names are\nprepended with a two-byte binary value (0x1B 0x00) that needs to be stripped off if you\nwant to use it. (In previous versions of Perl it wasn't possible to get the values of\nthese logical names, as the null byte acted as an end-of-string marker)\n\n$! The string value of $! is that returned by the CRTL's strerror() function, so it will\ninclude the VMS message for VMS-specific errors. The numeric value of $! is the value of\n\"errno\", except if errno is EVMSERR, in which case $! contains the value of vaxc$errno.\nSetting $! always sets errno to the value specified. If this value is EVMSERR, it also\nsets vaxc$errno to 4 (NONAME-F-NOMSG), so that the string value of $! won't reflect the\nVMS error message from before $! was set.\n\n$^E This variable provides direct access to VMS status values in vaxc$errno, which are often\nmore specific than the generic Unix-style error messages in $!. Its numeric value is the\nvalue of vaxc$errno, and its string value is the corresponding VMS message string, as\nretrieved by sys$getmsg(). Setting $^E sets vaxc$errno to the value specified.\n\nWhile Perl attempts to keep the vaxc$errno value to be current, if errno is not EVMSERR,\nit may not be from the current operation.\n\n$? The \"status value\" returned in $? is synthesized from the actual exit status of the\nsubprocess in a way that approximates POSIX wait(5) semantics, in order to allow Perl\nprograms to portably test for successful completion of subprocesses. The low order 8\nbits of $? are always 0 under VMS, since the termination status of a process may or may\nnot have been generated by an exception.\n\nThe next 8 bits contain the termination status of the program.\n\nIf the child process follows the convention of C programs compiled with the POSIXEXIT\nmacro set, the status value will contain the actual value of 0 to 255 returned by that\nprogram on a normal exit.\n\nWith the POSIXEXIT macro set, the Unix exit value of zero is represented as a VMS\nnative status of 1, and the Unix values from 2 to 255 are encoded by the equation:\n\nVMSstatus = 0x35a000 + (unixvalue * 8) + 1.\n\nAnd in the special case of Unix value 1 the encoding is:\n\nVMSstatus = 0x35a000 + 8 + 2 + 0x10000000.\n\nFor other termination statuses, the severity portion of the subprocess's exit status is\nused: if the severity was success or informational, these bits are all 0; if the severity\nwas warning, they contain a value of 1; if the severity was error or fatal error, they\ncontain the actual severity bits, which turns out to be a value of 2 for error and 4 for\nsevereerror. Fatal is another term for the severeerror status.\n\nAs a result, $? will always be zero if the subprocess's exit status indicated successful\ncompletion, and non-zero if a warning or error occurred or a program compliant with\nencoding POSIXEXIT values was run and set a status.\n\nHow can you tell the difference between a non-zero status that is the result of a VMS\nnative error status or an encoded Unix status? You can not unless you look at the\n${^CHILDERRORNATIVE} value. The ${^CHILDERRORNATIVE} value returns the actual VMS\nstatus value and check the severity bits. If the severity bits are equal to 1, then if\nthe numeric value for $? is between 2 and 255 or 0, then $? accurately reflects a value\npassed back from a Unix application. If $? is 1, and the severity bits indicate a VMS\nerror (2), then $? is from a Unix application exit value.\n\nIn practice, Perl scripts that call programs that return POSIXEXIT type status values\nwill be expecting those values, and programs that call traditional VMS programs will\neither be expecting the previous behavior or just checking for a non-zero status.\n\nAnd success is always the value 0 in all behaviors.\n\nWhen the actual VMS termination status of the child is an error, internally the $! value\nwill be set to the closest Unix errno value to that error so that Perl scripts that test\nfor error messages will see the expected Unix style error message instead of a VMS\nmessage.\n\nConversely, when setting $? in an END block, an attempt is made to convert the POSIX\nvalue into a native status intelligible to the operating system upon exiting Perl. What\nthis boils down to is that setting $? to zero results in the generic success value\nSS$NORMAL, and setting $? to a non-zero value results in the generic failure status\nSS$ABORT. See also \"exit\" in perlport.\n\nWith the \"PERLVMSPOSIXEXIT\" logical name defined as \"ENABLE\", setting $? will cause\nthe new value to be encoded into $^E so that either the original parent or child exit\nstatus values\n0 to 255 can be automatically recovered by C programs expecting POSIXEXIT behavior.\nIf both a parent and a child exit value are non-zero, then it will be assumed that this\nis actually a VMS native status value to be passed through. The special value of 0xFFFF\nis almost a NOOP as it will cause the current native VMS status in the C library to\nbecome the current native Perl VMS status, and is handled this way as it is known to not\nbe a valid native VMS status value. It is recommend that only values in the range of\nnormal Unix parent or child status numbers, 0 to 255 are used.\n\nThe pragma \"use vmsish 'status'\" makes $? reflect the actual VMS exit status instead of\nthe default emulation of POSIX status described above. This pragma also disables the\nconversion of non-zero values to SS$ABORT when setting $? in an END block (but zero will\nstill be converted to SS$NORMAL).\n\nDo not use the pragma \"use vmsish 'status'\" with \"PERLVMSPOSIXEXIT\" enabled, as they\nare at times requesting conflicting actions and the consequence of ignoring this advice\nwill be undefined to allow future improvements in the POSIX exit handling.\n\nIn general, with \"PERLVMSPOSIXEXIT\" enabled, more detailed information will be\navailable in the exit status for DCL scripts or other native VMS tools, and will give the\nexpected information for Posix programs. It has not been made the default in order to\npreserve backward compatibility.\n\nN.B. Setting \"DECC$FILENAMEUNIXREPORT\" implicitly enables \"PERLVMSPOSIXEXIT\".\n\n$| Setting $| for an I/O stream causes data to be flushed all the way to disk on each write\n(i.e. not just to the underlying RMS buffers for a file). In other words, it's\nequivalent to calling fflush() and fsync() from C.\n" }, { "name": "Standard modules with VMS-specific differences", "content": "SDBMFile\nSDBMFile works properly on VMS. It has, however, one minor difference. The database\ndirectory file created has a .sdbmdir extension rather than a .dir extension. .dir files are\nVMS filesystem directory files, and using them for other purposes could cause unacceptable\nproblems.\n" }, { "name": "Revision date", "content": "Please see the git repository for revision history.\n" } ] }, "AUTHOR": { "content": "Charles Bailey bailey@cor.newman.upenn.edu Craig Berry craigberry@mac.com Dan Sugalski\ndan@sidhe.org John Malmberg wb8tyw@qsl.net\n\n\n\nperl v5.34.0 2025-07-25 PERLVMS(1)", "subsections": [] } } } }