X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=vms%2Fperlvms.pod;h=53efdade2d2bdd60aaeb95446d7d7537522eb4c8;hb=6aaee015312976007994b80b72c65ab6b6237774;hp=c0cec10ef0248eecfa0cefe94b77896cee9c57c6;hpb=16d20bd98cd29be76029ebf04027a7edd34d817b;p=p5sagit%2Fp5-mst-13.2.git diff --git a/vms/perlvms.pod b/vms/perlvms.pod index c0cec10e..53efdad 100644 --- a/vms/perlvms.pod +++ b/vms/perlvms.pod @@ -1,4 +1,8 @@ -=head1 Notes on Perl 5 for VMS +=head1 NAME + +perlvms - VMS-specific documentation for Perl + +=head1 DESCRIPTION Gathered below are notes describing details of Perl 5's behavior on VMS. They are a supplement to the regular Perl 5 @@ -13,11 +17,17 @@ subdirectory of the Perl distribution. We hope these notes will save you from confusion and lost sleep when writing Perl scripts on VMS. If you find we've missed something you think should appear here, please don't -hesitate to drop a line to vmsperl@genetics.upenn.edu. +hesitate to drop a line to vmsperl@perl.org. + +=head1 Installation + +Directions for building and installing Perl 5 can be found in +the file F in the main source directory of the +Perl distribution.. -=head1 Organization of Perl +=head1 Organization of Perl Images -=head2 Perl Images +=head2 Core Images During the installation process, three Perl images are produced. F is an executable image which contains all of @@ -48,7 +58,7 @@ define a foreign command to invoke this image. Perl extensions are packages which provide both XS and Perl code to add new functionality to perl. (XS is a meta-language which simplifies writing C code which interacts with Perl, see -L for more details.) The Perl code for an +L for more details.) The Perl code for an extension is treated like any other library module - it's made available in your script through the appropriate C or C statement, and usually defines a Perl @@ -75,7 +85,7 @@ for the extension, and F, a Perl script which uses the C library modules supplied with Perl to generate a F file for the extension. -=head3 Installing static extensions +=head2 Installing static extensions Since static extensions are incorporated directly into F, you'll have to rebuild Perl to incorporate a @@ -94,114 +104,218 @@ of the extension, with all C<::> replaced by C<.> (e.g. the library module for extension Foo::Bar would be copied to a F<[.Foo.Bar]> subdirectory). -=head3 Installic dynamic extensions - -First, you'll need to compile the XS code into a shareable image, -either by hand or using the F supplied with the -extension. If you're building the shareable image by hand, please -note the following points: - - The shareable image must be linked to F, so it - has access to Perl's global variables and routines. In - order to specify the correct attributes for psects in - F, you should include the linker options file - F in the Link command. (This file is - generated when F is built, and is found in the - main Perl source directory. - - The entry point for the CI routine (where - I is the name of the extension, with all C<::> - replaced by C<__>) must be a universal symbol. No other - universal symbols are required to use the shareable image - with Perl, though you may want to include additional - universal symbols if you plan to share code or data among - different extensions. -The shareable image can be placed in any of several locations: - - the F<[.Auto.>IF<]> subdirectory of one of - the directories in C<@INC>, where I is the - name of the extension, with each C<::> translated to C<.> - (e.g. for extension Foo::Bar, you would use the - F<[.Auto.Foo.Bar]> subdirectory), or - - one of the directories in C<@INC>, or - - a directory which the extensions Perl library module - passes to the DynaLoader when asking it to map - the shareable image, or - - F or F. +=head2 Installing dynamic extensions + +In general, the distributed kit for a Perl extension includes +a file named Makefile.PL, which is a Perl program which is used +to create a F file which can be used to build and +install the files required by the extension. The kit should be +unpacked into a directory tree B under the main Perl source +directory, and the procedure for building the extension is simply + + $ perl Makefile.PL ! Create Descrip.MMS + $ mmk ! Build necessary files + $ mmk test ! Run test code, if supplied + $ mmk install ! Install into public Perl tree + +I The procedure by which extensions are built and +tested creates several levels (at least 4) under the +directory in which the extension's source files live. +For this reason if you are running a version of VMS prior +to V7.1 you shouldn't nest the source directory +too deeply in your directory structure lest you exceed RMS' +maximum of 8 levels of subdirectory in a filespec. (You +can use rooted logical names to get another 8 levels of +nesting, if you can't place the files near the top of +the physical directory structure.) + +VMS support for this process in the current release of Perl +is sufficient to handle most extensions. However, it does +not yet recognize extra libraries required to build shareable +images which are part of an extension, so these must be added +to the linker options file for the extension by hand. For +instance, if the F extension to Perl requires the +F shareable image in order to properly link +the Perl extension, then the line C must +be added to the linker options file F produced +during the build process for the Perl extension. + +By default, the shareable image for an extension is placed in +the F<[.lib.site_perl.auto>I.IF<]> directory of the +installed Perl directory tree (where I is F or +F, and I is the name of the extension, with +each C<::> translated to C<.>). (See the MakeMaker documentation +for more details on installation options for extensions.) +However, it can be manually placed in any of several locations: + +=over 4 + +=item * + +the F<[.Lib.Auto.>II<$PVers>IF<]> subdirectory +of one of the directories in C<@INC> (where I +is the version of Perl you're using, as supplied in C<$]>, +with '.' converted to '_'), or + +=item * + +one of the directories in C<@INC>, or + +=item * + +a directory which the extensions Perl library module +passes to the DynaLoader when asking it to map +the shareable image, or + +=item * + +F or F. + +=back + If the shareable image isn't in any of these places, you'll need to define a logical name I, where I is the portion of the extension's name after the last C<::>, which translates to the full file specification of the shareable image. -Once you've got the shareable image set up, you should copy the -extension's Perl library module to the appropriate library directory -(see the section above on installing static extensions). +=head1 File specifications -=head1 Installation - -Directions for building and installing Perl 5 can be found in -the file F in the main source directory of the -Perl distribution.. - -=head1 File specifications +=head2 Syntax We have tried to make Perl aware of both VMS-style and Unix- style file specifications wherever possible. You may use either style, or both, on the command line and in scripts, -but you may not combine the two styles within a single fle -specfication. Filenames are, of course, still case- -insensitive. For consistency, most Perl routines return -filespecs using lower case latters only, regardless of the -case used in the arguments passed to them. (This is true -only when running under VMS; Perl respects the case- -sensitivity of OSs like Unix.) +but you may not combine the two styles within a single file +specification. VMS Perl interprets Unix pathnames in much +the same way as the CRTL (I the first component of +an absolute path is read as the device name for the +VMS file specification). There are a set of functions +provided in the C package for explicit +interconversion between VMS and Unix syntax; its +documentation provides more details. + +Perl is now in the process of evolving to follow the setting of +the DECC$* feature logical names in the interpretation of UNIX pathnames. +This is still a work in progress. + +For handling extended characters, and case sensitivity, as long as +DECC$POSIX_COMPLIANT_PATHNAMES, DECC$FILENAME_UNIX_REPORT, and +DECC$FILENAME_UNIX_ONLY are not set, then the older Perl behavior +for conversions of file specifications from UNIX to VMS is followed, +except that VMS paths with concealed rooted logical names are now +translated correctly to UNIX paths. + +With those features set, then new routines may handle the translation, +because some of the rules are different. The presence of ./.../ +in a UNIX path is no longer translated to the VMS [...]. It will +translate to [.^.^.^.]. To be compatible with what MakeMaker expects, +if a VMS path can not be translated to a UNIX path when unixify +is called, it is passed through unchanged. So unixify("[...]") will +return "[...]". + +The handling of extended characters will also be better with the +newer translation routines. But more work is needed to fully support +extended file syntax names. In particular, at this writing Pathtools +can not deal with directories containing some extended characters. + +There are several ambiguous cases where a conversion routine can not +determine if an input filename is in UNIX format or in VMS format, +since now both VMS UNIX file specifications can have characters in +them that could be mistaken for syntax delimiters of the other type. +So some pathnames simply can not be used in a mode that allows either +type of pathname to be present. + +Perl will tend to assume that an ambiguous filename is in UNIX format. + +Allowing "." as a version delimiter is simply incompatible with +determining if a pathname is already VMS format or UNIX with the +extended file syntax. There is no way to know if "perl-5.8.6" that +TAR produces is a UNIX "perl-5.8.6" or a VMS "perl-5.8;6" when +passing it to unixify() or vmsify(). + +The DECC$FILENAME_UNIX_REPORT or the DECC$FILENAME_UNIX_ONLY logical +names control how Perl interprets filenames. + +The DECC$FILENAME_UNIX_ONLY setting has not been tested at this time. +Perl uses traditional OpenVMS file specifications internally and in +the test harness, so this mode may have limited use, or require more +changes to make usable. + +Everything about DECC$FILENAME_UNIX_REPORT should be assumed to apply +to DECC$FILENAME_UNIX_ONLY mode. The DECC$FILENAME_UNIX_ONLY differs +in that it expects all filenames passed to the C runtime to be already +in UNIX format. + +Again, currently most of the core Perl modules have not yet been updated +to understand that VMS is not as limited as it use to be. Fixing that +is a work in progress. + +The logical name DECC$POSIX_COMPLIANT_PATHNAMES is new with the +RMS Symbolic Link SDK. This version of Perl does not support it being set. + + +Filenames are case-insensitive on VAX, and on ODS-2 formatted +volumes on ALPHA and I64. + +On ODS-5 volumes filenames are case preserved and on newer +versions of OpenVMS can be optionally case sensitive. + +On ALPHA and I64, Perl is in the process of being changed to follow the +process case sensitivity setting to report if the file system is case +sensitive. + +Perl programs should not assume that VMS is case blind, or that +filenames will be in lowercase. + +Programs should use the File::Spec:case_tolerant setting to determine +the state, and not the $^O setting. + +For consistency, when the above feature is clear and when not +otherwise overridden by DECC feature logical names, most Perl routines +return file specifications using lower case letters only, +regardless of the case used in the arguments passed to them. +(This is true only when running under VMS; Perl respects the +case-sensitivity of OSs like Unix.) We've tried to minimize the dependence of Perl library modules on Unix syntax, but you may find that some of these, as well as some scripts written for Unix systems, will require that you use Unix syntax, since they will assume that -'/' is the directory separator, etc. If you find instances +'/' is the directory separator, I If you find instances of this in the Perl distribution itself, please let us know, so we can try to work around them. -=head1 Command line redirection - -Perl for VMS supports redirection of input and output on the -command line, using a subset of Bourne shell syntax: - reads stdin from F, - >F writes stdout to F, - >>F appends stdout to F, - 2>F writes stderr to F, and - 2>>F appends stderr to F. - -In addition, output may be piped to a subprocess, using the -character '|'. Anything after this character on the command -line is passed to a subprocess for execution; the subprocess -takes the output of Perl as its input. - -Finally, if the command line ends with '&', the entire -command is run in the background as an asynchronous -subprocess. +Also when working on Perl programs on VMS, if you need a syntax +in a specific operating system format, then you need to either +check the appropriate DECC$ feature logical, or call a conversion +routine to force it to that format. -=head1 Pipes - -Input and output pipes to Perl filehandles are supported; the -"file name" is passed to lib$spawn() for asynchronous -execution. You should be careful to close any pipes you have -opened in a Perl script, lest you leave any "orphaned" -subprocesses around when Perl exits. - -You may also use backticks to invoke a DCL subprocess, whose -output is used as the return value of the expression. The -string between the backticks is passed directly to lib$spawn -as the command to execute. In this case, Perl will wait for -the subprocess to complete before continuing. - -=head1 Wildcard expansion +=head2 Wildcard expansion File specifications containing wildcards are allowed both on -the command line and within Perl globs (e.g. >). If +the command line and within Perl globs (e.g. C*.cE>). If the wildcard filespec uses VMS syntax, the resultant filespecs will follow VMS syntax; if a Unix-style filespec is -passed in, Unix-style filespecs will be returned.. - +passed in, Unix-style filespecs will be returned. +Similar to the behavior of wildcard globbing for a Unix shell, +one can escape command line wildcards with double quotation +marks C<"> around a perl program command line argument. However, +owing to the stripping of C<"> characters carried out by the C +handling of argv you will need to escape a construct such as +this one (in a directory containing the files F, F, +F, and F): + + $ perl -e "print join(' ',@ARGV)" perl.* + perl.c perl.exe perl.h perl.obj + +in the following triple quoted manner: + + $ perl -e "print join(' ',@ARGV)" """perl.*""" + perl.* + +In both the case of unquoted command line arguments or in calls +to C VMS wildcard expansion is performed. (csh-style +wildcard expansion is available if you use C.) If the wildcard filespec contains a device or directory specification, then the resultant filespecs will also contain a device and directory; otherwise, device and directory @@ -215,39 +329,152 @@ of C<[.t]*.*> will yield filespecs like yield filespecs like "t/base.dir". (This is done to match the behavior of glob expansion performed by Unix shells.) -Similarly, the resultant filespec will the file version only -if one was present in the input filespec. +Similarly, the resultant filespec will contain the file version +only if one was present in the input filespec. + + +=head2 Pipes + +Input and output pipes to Perl filehandles are supported; the +"file name" is passed to lib$spawn() for asynchronous +execution. You should be careful to close any pipes you have +opened in a Perl script, lest you leave any "orphaned" +subprocesses around when Perl exits. + +You may also use backticks to invoke a DCL subprocess, whose +output is used as the return value of the expression. The +string between the backticks is handled as if it were the +argument to the C operator (see below). In this case, +Perl will wait for the subprocess to complete before continuing. + +The mailbox (MBX) that perl can create to communicate with a pipe +defaults to a buffer size of 512. The default buffer size is +adjustable via the logical name PERL_MBX_SIZE provided that the +value falls between 128 and the SYSGEN parameter MAXBUF inclusive. +For example, to double the MBX size from the default within +a Perl program, use C<$ENV{'PERL_MBX_SIZE'} = 1024;> and then +open and use pipe constructs. An alternative would be to issue +the command: + + $ Define PERL_MBX_SIZE 1024 + +before running your wide record pipe program. A larger value may +improve performance at the expense of the BYTLM UAF quota. =head1 PERL5LIB and PERLLIB -The PERL5LIB and PERLLIB logical names work as -documented L, except that the element -separator is '|' instead of ':'. The directory -specifications may use either VMS or Unix syntax. - -=head1 %ENV - -Reading the elements of the %ENV array returns the -translation of the logical name specified by the key, -according to the normal search order of access modes and -logical name tables. In addition, the keys C, -C,C, and C return the CRTL "environment -variables" of the same names. The key C returns the -current default device and directory specification. - -Setting an element of %ENV defines a supervisor-mode logical -name in the process logical name table. Cing or -Cing an element of %ENV deletes the equivalent user- -mode or supervisor-mode logical name from the process logical -name table. If you use C, the %ENV element remains -empty. If you use C, another attempt is made at -logical name translation after the deletion, so an inner-mode -logical name or a name in another logical name table will -replace the logical name just deleted. +The PERL5LIB and PERLLIB logical names work as documented in L, +except that the element separator is '|' instead of ':'. The +directory specifications may use either VMS or Unix syntax. -In all operations on %ENV, the key string is treated as if it -were entirely uppercase, regardless of the case actually -specified in the Perl expression. +=head1 PERL_VMS_EXCEPTION_DEBUG + +The PERL_VMS_EXCEPTION_DEBUG being defined as "ENABLE" will cause the VMS +debugger to be invoked if a fatal exception that is not otherwise +handled is raised. The purpose of this is to allow debugging of +internal Perl problems that would cause such a condition. + +This allows the programmer to look at the execution stack and variables to +find out the cause of the exception. As the debugger is being invoked as +the Perl interpreter is about to do a fatal exit, continuing the execution +in debug mode is usally not practical. + +Starting Perl in the VMS debugger may change the program execution +profile in a way that such problems are not reproduced. + +The C function can be used to test this functionality from within +a program. + +In typical VMS style, only the first letter of the value of this logical +name is actually checked in a case insensitive mode, and it is considered +enabled if it is the value "T","1" or "E". + +This logical name must be defined before Perl is started. + +=head1 Command line + +=head2 I/O redirection and backgrounding + +Perl for VMS supports redirection of input and output on the +command line, using a subset of Bourne shell syntax: + +=over 4 + +=item * + +Cfile> reads stdin from C, + +=item * + +Cfile> writes stdout to C, + +=item * + +CEfile> appends stdout to C, + +=item * + +C<2Efile> writes stderr to C, + +=item * + +C<2EEfile> appends stderr to C, and + +=item * + +C<< 2>&1 >> redirects stderr to stdout. + +=back + +In addition, output may be piped to a subprocess, using the +character '|'. Anything after this character on the command +line is passed to a subprocess for execution; the subprocess +takes the output of Perl as its input. + +Finally, if the command line ends with '&', the entire +command is run in the background as an asynchronous +subprocess. + +=head2 Command line switches + +The following command line switches behave differently under +VMS than described in L. Note also that in order +to pass uppercase switches to Perl, you need to enclose +them in double-quotes on the command line, since the CRTL +downcases all unquoted strings. + +On newer 64 bit versions of OpenVMS, a process setting now +controls if the quoting is needed to preserve the case of +command line arguments. + +=over 4 + +=item -i + +If the C<-i> switch is present but no extension for a backup +copy is given, then inplace editing creates a new version of +a file; the existing copy is not deleted. (Note that if +an extension is given, an existing file is renamed to the backup +file, as is the case under other operating systems, so it does +not remain as a previous version under the original filename.) + +=item -S + +If the C<"-S"> or C<-"S"> switch is present I the script +name does not contain a directory, then Perl translates the +logical name DCL$PATH as a searchlist, using each translation +as a directory in which to look for the script. In addition, +if no file type is specified, Perl looks in each directory +for a file matching the name specified, with a blank type, +a type of F<.pl>, and a type of F<.com>, in that order. + +=item -u + +The C<-u> switch causes the VMS debugger to be invoked +after the Perl program is compiled, but before it has +run. It does not create a core dump file. + +=back =head1 Perl functions @@ -255,42 +482,51 @@ As of the time this document was last revised, the following Perl functions were implemented in the VMS port of Perl (functions marked with * are discussed in more detail below): - file tests*, abs, alarm, atan, binmode*, bless, + file tests*, abs, alarm, atan, backticks*, binmode*, bless, caller, chdir, chmod, chown, chomp, chop, chr, - close, closedir, cos, defined, delete, die, do, - each, endpwent, eof, eval, exec*, exists, exit, - exp, fileno, fork*, getc, getpwent*, getpwnam*, - getpwuid*, glob, goto, grep, hex, import, index, - int, join, keys, kill, last, lc, lcfirst, length, - local, localtime, log, m//, map, mkdir, my, next, - no, oct, open, opendir, ord, pack, pipe, pop, pos, - print, printf, push, q//, qq//, qw//, qx//, - quotemeta, rand, read, readdir, redo, ref, rename, + close, closedir, cos, crypt*, defined, delete, + die, do, dump*, each, endpwent, eof, eval, exec*, + exists, exit, exp, fileno, getc, getlogin, getppid, + getpwent*, getpwnam*, getpwuid*, glob, gmtime*, goto, + grep, hex, import, index, int, join, keys, kill*, + last, lc, lcfirst, length, local, localtime, log, m//, + map, mkdir, my, next, no, oct, open, opendir, ord, pack, + pipe, pop, pos, print, printf, push, q//, qq//, qw//, + qx//*, quotemeta, rand, read, readdir, redo, ref, rename, require, reset, return, reverse, rewinddir, rindex, - rmdir, s///, scalar, seek, seekdir, select(internal)*, - setpwent, shift, sin, sleep, sort, splice, split, - sprintf, sqrt, srand, stat, study, substr, sysread, - system*, syswrite, tell, telldir, tie, time, times*, - tr///, uc, ucfirst, umask, undef, unlink*, unpack, - untie, unshift, use, utime*, values, vec, wait, - waitpid*, wantarray, warn, write, y/// + rmdir, s///, scalar, seek, seekdir, select(internal), + select (system call)*, setpwent, shift, sin, sleep, + sort, splice, split, sprintf, sqrt, srand, stat, + study, substr, sysread, system*, syswrite, tell, + telldir, tie, time, times*, tr///, uc, ucfirst, umask, + undef, unlink*, unpack, untie, unshift, use, utime*, + values, vec, wait, waitpid*, wantarray, warn, write, y/// The following functions were not implemented in the VMS port, and calling them produces a fatal error (usually) or undefined behavior (rarely, we hope): - chroot, crypt, dbmclose, dbmopen, dump, fcntl, - flock, getlogin, getpgrp, getppid, getpriority, - getgrent, kill, getgrgid, getgrnam, setgrent, - endgrent, gmtime, ioctl, link, lstst, msgctl, - msgget, msgsend, msgrcv, readlink, - select(system call), semctl, semget, semop, - setpgrp, setpriority, shmctl, shmget, shmread, - shmwrite, socketpair, symlink, syscall, truncate + chroot, dbmclose, dbmopen, flock, fork*, + getpgrp, getpriority, getgrent, getgrgid, + getgrnam, setgrent, endgrent, ioctl, link, lstat, + msgctl, msgget, msgsend, msgrcv, readlink, semctl, + semget, semop, setpgrp, setpriority, shmctl, shmget, + shmread, shmwrite, socketpair, symlink, syscall + +The following functions are available on Perls compiled with Dec C +5.2 or greater and running VMS 7.0 or greater: + + truncate + +The following functions are available on Perls built on VMS 7.2 or +greater: + + fcntl (without locking) The following functions may or may not be implemented, depending on what type of socket support you've built into your copy of Perl: + accept, bind, connect, getpeername, gethostbyname, getnetbyname, getprotobyname, getservbyname, gethostbyaddr, getnetbyaddr, @@ -298,9 +534,41 @@ your copy of Perl: getnetent, getprotoent, getservent, sethostent, setnetent, setprotoent, setservent, endhostent, endnetent, endprotoent, endservent, getsockname, - getsockopt, listen, recv, send, setsockopt, - shutdown, socket + getsockopt, listen, recv, select(system call)*, + send, setsockopt, shutdown, socket + +The following function is available on Perls built on 64 bit OpenVMS 8.2 +with hard links enabled on an ODS-5 formatted build disk. If someone with +an OpenVMS 7.3-1 system were to modify configure.com and test the results, +this feature can be brought back to OpenVMS 7.3-1 and later. Hardlinks +must be enabled on the build disk because if the build procedure sees +this feature enabled, it uses it. + + link + +The following functions are available on Perls built on 64 bit OpenVMS +8.2 and can be implemented on OpenVMS 7.3-2 if someone were to modify +configure.com and test the results. (While in the build, at the time +of this writing, they have not been specifically tested.) + + getgrgid, getgrnam, getpwnam, getpwuid, + setgrent, ttyname + +The following functions are available on Perls built on 64 bit OpenVMS 8.2 +and later. (While in the build, at the time of this writing, they have +not been specifically tested.) + statvfs, socketpair + +The following functions are expected to soon be available on Perls built +on 64 bit OpenVMS 8.2 or later with the RMS Symbolic link package. Use +of symbolic links at this time effectively requires the +DECC$POSIX_COMPLIANT_PATHNAMES to defined as 3, and operating in a +DECC$FILENAME_UNIX_REPORT mode. + + lchown, link, lstat, readlink, symlink + +=over 4 =item File tests @@ -319,56 +587,151 @@ st_mode field. Finally, C<-d> returns true if passed a device specification without an explicit directory (e.g. C), as well as if passed a directory. +There are DECC feature logical names AND ODS-5 volume attributes that +also control what values are returned for the date fields. + +Note: Some sites have reported problems when using the file-access +tests (C<-r>, C<-w>, and C<-x>) on files accessed via DEC's DFS. +Specifically, since DFS does not currently provide access to the +extended file header of files on remote volumes, attempts to +examine the ACL fail, and the file tests will return false, +with C<$!> indicating that the file does not exist. You can +use C on these files, since that checks UIC-based protection +only, and then manually check the appropriate bits, as defined by +your C compiler's F, in the mode value it returns, if you +need an approximation of the file's protections. + +=item backticks + +Backticks create a subprocess, and pass the enclosed string +to it for execution as a DCL command. Since the subprocess is +created directly via C, any valid DCL command string +may be specified. + =item binmode FILEHANDLE -The C operator has no effect under VMS. It will -return TRUE whenever called, but will not affect I/O -operations on the filehandle given as its argument. +The C operator will attempt to insure that no translation +of carriage control occurs on input from or output to this filehandle. +Since this involves reopening the file and then restoring its +file position indicator, if this function returns FALSE, the +underlying filehandle may no longer point to an open file, or may +point to a different position in the file than before C +was called. + +Note that C is generally not necessary when using normal +filehandles; it is provided so that you can control I/O to existing +record-structured files when necessary. You can also use the +C function in the VMS::Stdio extension to gain finer +control of I/O to files and devices with different record structures. + +=item crypt PLAINTEXT, USER + +The C operator uses the C system +service to generate the hashed representation of PLAINTEXT. +If USER is a valid username, the algorithm and salt values +are taken from that user's UAF record. If it is not, then +the preferred algorithm and a salt of 0 are used. The +quadword encrypted value is returned as an 8-character string. + +The value returned by C may be compared against +the encrypted password from the UAF returned by the C +functions, in order to authenticate users. If you're +going to do this, remember that the encrypted password in +the UAF was generated using uppercase username and +password strings; you'll have to upcase the arguments to +C to insure that you'll get the proper value: + + sub validate_passwd { + my($user,$passwd) = @_; + my($pwdhash); + if ( !($pwdhash = (getpwnam($user))[1]) || + $pwdhash ne crypt("\U$passwd","\U$name") ) { + intruder_alert($name); + } + return 1; + } + + +=item die + +C will force the native VMS exit status to be an SS$_ABORT code +if neither of the $! or $? status values are ones that would cause +the native status to be interpreted as being what VMS classifies as +SEVERE_ERROR severity for DCL error handling. + +When the future POSIX_EXIT mode is active, C, the native VMS exit +status value will have either one of the C<$!> or C<$?> or C<$^E> or +the UNIX value 255 encoded into it in a way that the effective original +value can be decoded by other programs written in C, including Perl +and the GNV package. As per the normal non-VMS behavior of C if +either C<$!> or C<$?> are non-zero, one of those values will be +encoded into a native VMS status value. If both of the UNIX status +values are 0, and the C<$^E> value is set one of ERROR or SEVERE_ERROR +severity, then the C<$^E> value will be used as the exit code as is. +If none of the above apply, the UNIX value of 255 will be encoded into +a native VMS exit status value. + +Please note a significant difference in the behavior of C in +the future POSIX_EXIT mode is that it does not force a VMS +SEVERE_ERROR status on exit. The UNIX exit values of 2 through +255 will be encoded in VMS status values with severity levels of +SUCCESS. The UNIX exit value of 1 will be encoded in a VMS status +value with a severity level of ERROR. This is to be compatible with +how the VMS C library encodes these values. + +The minimum severity level set by C in a future POSIX_EXIT mode +may be changed to be ERROR or higher before that mode becomes fully active +depending on the results of testing and further review. If this is +done, the behavior of c in the future POSIX_EXIT will close enough +to the default mode that most DCL shell scripts will probably not notice +a difference. + +See C<$?> for a description of the encoding of the UNIX value to +produce a native VMS status containing it. + + +=item dump + +Rather than causing Perl to abort and dump core, the C +operator invokes the VMS debugger. If you continue to +execute the Perl program under the debugger, control will +be transferred to the label specified as the argument to +C, or, if no label was specified, back to the +beginning of the program. All other state of the program +(I values of variables, open file handles) are not +affected by calling C. =item exec LIST -The C operator behaves in one of two different ways. -If called after a call to C, it will invoke the CRTL -C routine, passing its arguments to the subprocess -created by C for execution. In this case, it is -subject to all limitations that affect C. (In -particular, this usually means that the command executed in -the subprocess must be an image compiled from C source code, -and that your options for passing file descriptors and signal -handlers to the subprocess are limited.) - -If the call to C does not follow a call to C, it -will cause Perl to exit, and to invoke the command given as -an argument to C via C. If the argument -begins with a '$' (other than as part of a filespec), then it -is executed as a DCL command. Otherwise, the first token on -the command line is treated as the filespec of an image to -run, and an attempt is made to invoke it (using F<.Exe> and -the process defaults to expand the filespec) and pass the -rest of C's argument to it as parameters. - -You can use C in both ways within the same script, as -long as you call C and C in pairs. Perl -keeps track of how many times C and C have been -called, and will call the CRTL C routine if there have -previously been more calls to C than to C. +A call to C will cause Perl to exit, and to invoke the command +given as an argument to C via C. If the +argument begins with '@' or '$' (other than as part of a filespec), +then it is executed as a DCL command. Otherwise, the first token on +the command line is treated as the filespec of an image to run, and +an attempt is made to invoke it (using F<.Exe> and the process +defaults to expand the filespec) and pass the rest of C's +argument to it as parameters. If the token has no file type, and +matches a file with null type, then an attempt is made to determine +whether the file is an executable image which should be invoked +using C or a text file which should be passed to DCL as a +command procedure. =item fork -The C operator works in the same way as the CRTL -C routine, which is quite different under VMS than -under Unix. Specifically, while C returns 0 after it -is called and the subprocess PID after C is called, in -both cases the thread of execution is within the parent -process, so there is no opportunity to perform operations in -the subprocess before calling C. - -In general, the use of C and C to create -subprocess is not recommended under VMS; wherever possible, -use the C operator or piped filehandles instead. +While in principle the C operator could be implemented via +(and with the same rather severe limitations as) the CRTL C +routine, and while some internal support to do just that is in +place, the implementation has never been completed, making C +currently unavailable. A true kernel C is expected in a +future version of VMS, and the pseudo-fork based on interpreter +threads may be available in a future version of Perl on VMS (see +L). In the meantime, use C, backticks, or piped +filehandles to create subprocesses. =item getpwent + =item getpwnam + =item getpwuid These operators obtain the information described in L, @@ -380,6 +743,43 @@ contains the login directory in Unix syntax. The C<$gcos> item contains the owner field from the UAF record. The C<$quota> item is not used. +=item gmtime + +The C operator will function properly if you have a +working CRTL C routine, or if the logical name +SYS$TIMEZONE_DIFFERENTIAL is defined as the number of seconds +which must be added to UTC to yield local time. (This logical +name is defined automatically if you are running a version of +VMS with built-in UTC support.) If neither of these cases is +true, a warning message is printed, and C is returned. + +=item kill + +In most cases, C is implemented via the CRTL's C +function, so it will behave according to that function's +documentation. If you send a SIGKILL, however, the $DELPRC system +service is called directly. This insures that the target +process is actually deleted, if at all possible. (The CRTL's C +function is presently implemented via $FORCEX, which is ignored by +supervisor-mode images like DCL.) + +Also, negative signal values don't do anything special under +VMS; they're just converted to the corresponding positive value. + +=item qx// + +See the entry on C above. + +=item select (system call) + +If Perl was not built with socket support, the system call +version of C functions only for file descriptors attached +to sockets. It will not provide information about regular +files or pipes, since the CRTL C routine does not +provide this functionality. + =item stat EXPR Since VMS keeps track of files according to a different scheme @@ -393,12 +793,36 @@ though, so caveat scriptor. The C operator creates a subprocess, and passes its arguments to the subprocess for execution as a DCL command. -Since the subprocess is created directly via lib$spawn, any -valid DCL command string may be specified. If LIST consists -of the empty string, C spawns an interactive DCL subprocess, -in the same fashion as typiing B at the DCL prompt. +Since the subprocess is created directly via C, any +valid DCL command string may be specified. If the string begins with +'@', it is treated as a DCL command unconditionally. Otherwise, if +the first token contains a character used as a delimiter in file +specification (e.g. C<:> or C<]>), an attempt is made to expand it +using a default type of F<.Exe> and the process defaults, and if +successful, the resulting file is invoked via C. This allows you +to invoke an image directly simply by passing the file specification +to C, a common Unixish idiom. If the token has no file type, +and matches a file with null type, then an attempt is made to +determine whether the file is an executable image which should be +invoked using C or a text file which should be passed to DCL +as a command procedure. + +If LIST consists of the empty string, C spawns an +interactive DCL subprocess, in the same fashion as typing +B at the DCL prompt. + Perl waits for the subprocess to complete before continuing -execution in the current process. +execution in the current process. As described in L, +the return value of C is a fake "status" which follows +POSIX semantics unless the pragma C is in +effect; see the description of C<$?> in this document for more +detail. + +=item time + +The value returned by C