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@newman.upenn.edu.
+hesitate to drop a line to vmsperl@perl.org.
=head1 Installation
I<N.B.> 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, you shouldn't nest the source directory
-too deeply in your directory structure, lest you eccedd RMS'
+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
be added to the linker options file F<PGPLOT.Opt> produced
during the build process for the Perl extension.
-By default, the shareable image for an extension is placed
-F<[.lib.site_perl.auto>I<Arch>.I<Extname>F<]> directory of the
+By default, the shareable image for an extension is placed in
+the F<[.lib.site_perl.auto>I<Arch>.I<Extname>F<]> directory of the
installed Perl directory tree (where I<Arch> is F<VMS_VAX> or
F<VMS_AXP>, and I<Extname> 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:
- - the F<[.Lib.Auto.>I<Arch>I<$PVers>I<Extname>F<]> subdirectory
- of one of the directories in C<@INC> (where I<PVers>
- is the version of Perl you're using, as supplied in C<$]>,
- with '.' converted to '_'), 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<Sys$Share> or F<Sys$Library>.
+
+=over 4
+
+=item *
+
+the F<[.Lib.Auto.>I<Arch>I<$PVers>I<Extname>F<]> subdirectory
+of one of the directories in C<@INC> (where I<PVers>
+is the version of Perl you're using, as supplied in C<$]>,
+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<Sys$Share> or F<Sys$Library>.
+
+=back
+
If the shareable image isn't in any of these places, you'll need
to define a logical name I<Extshortname>, where I<Extshortname>
is the portion of the extension's name after the last C<::>, which
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
+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<e.g.> the first component of
an absolute path is read as the device name for the
=head2 Wildcard expansion
File specifications containing wildcards are allowed both on
-the command line and within Perl globs (e.g. <CE<lt>*.cE<gt>>). If
+the command line and within Perl globs (e.g. C<E<lt>*.cE<gt>>). 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.
+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<PERL.C>, F<PERL.EXE>,
+F<PERL.H>, and F<PERL.OBJ>):
+
+ $ perl -e "print join(' ',@ARGV)" perl.*
+ perl.c perl.exe perl.h perl.obj
+
+in the following triple quoted manner:
-In both cases, VMS wildcard expansion is performed. (csh-style
+ $ perl -e "print join(' ',@ARGV)" """perl.*"""
+ perl.*
+
+In both the case of unquoted command line arguments or in calls
+to C<glob()> VMS wildcard expansion is performed. (csh-style
wildcard expansion is available if you use C<File::Glob::glob>.)
If the wildcard filespec contains a device or directory
specification, then the resultant filespecs will also contain
argument to the C<system> 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<perl>,
+The PERL5LIB and PERLLIB logical names work as documented in L<perl>,
except that the element separator is '|' instead of ':'. The
directory specifications may use either VMS or Unix syntax.
Perl for VMS supports redirection of input and output on the
command line, using a subset of Bourne shell syntax:
- <F<file> reads stdin from F<file>,
- >F<file> writes stdout to F<file>,
- >>F<file> appends stdout to F<file>,
- 2>F<file> writes stderr to F<file>, and
- 2>>F<file> appends stderr to F<file>.
+=over 4
+
+=item *
+
+C<E<lt>file> reads stdin from C<file>,
+
+=item *
+
+C<E<gt>file> writes stdout to C<file>,
+
+=item *
+
+C<E<gt>E<gt>file> appends stdout to C<file>,
+
+=item *
+
+C<2E<gt>file> writes stderr to C<file>,
+
+=item *
+
+C<2E<gt>E<gt>file> appends stderr to C<file>, 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
=item -S
-If the C<-S> switch is present I<and> the script name does
-not contain a directory, then Perl translates the logical
-name DCL$PATH as a searchlist, using each translation as
-a directory in which to look for the script. In addition,
+If the C<"-S"> or C<-"S"> switch is present I<and> the script
+name does not contain a directory, then Perl translates the
+logical name DCL$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.
caller, chdir, chmod, chown, chomp, chop, chr,
close, closedir, cos, crypt*, defined, delete,
die, do, dump*, each, endpwent, eof, eval, exec*,
- exists, exit, exp, fileno, fork*, getc, getlogin,
+ 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//,
and calling them produces a fatal error (usually) or
undefined behavior (rarely, we hope):
- chroot, dbmclose, dbmopen, fcntl, flock,
- getpgrp, getppid, getpriority, getgrent, getgrgid,
+ 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
+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:
password strings; you'll have to upcase the arguments to
C<crypt> 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);
+ 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;
}
- return 1;
- }
=item dump
=item exec LIST
-The C<exec> operator behaves in one of two different ways.
-If called after a call to C<fork>, it will invoke the CRTL
-C<execv()> routine, passing its arguments to the subprocess
-created by C<fork> for execution. In this case, it is
-subject to all limitations that affect C<execv()>. (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<exec> does not follow a call to C<fork>, it
-will cause Perl to exit, and to invoke the command given as
-an argument to C<exec> via C<lib$do_command>. If the argument
-begins with '@' or '$' (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<exec>'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<MCR> or a text file which
-should be passed to DCL as a command procedure.
-
-You can use C<exec> in both ways within the same script, as
-long as you call C<fork> and C<exec> in pairs. Perl
-keeps track of how many times C<fork> and C<exec> have been
-called, and will call the CRTL C<execv()> routine if there have
-previously been more calls to C<fork> than to C<exec>.
+A call to C<exec> will cause Perl to exit, and to invoke the command
+given as an argument to C<exec> via C<lib$do_command>. If the
+argument begins with '@' or '$' (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<exec>'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<MCR> or a text file which should be passed to DCL as a
+command procedure.
=item fork
-The C<fork> operator works in the same way as the CRTL
-C<vfork()> routine, which is quite different under VMS than
-under Unix. Specifically, while C<fork> returns 0 after it
-is called and the subprocess PID after C<exec> 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<exec>.
-
-In general, the use of C<fork> and C<exec> to create
-subprocess is not recommended under VMS; wherever possible,
-use the C<system> operator or piped filehandles instead.
+While in principle the C<fork> operator could be implemented via
+(and with the same rather severe limitations as) the CRTL C<vfork()>
+routine, and while some internal support to do just that is in
+place, the implementation has never been completed, making C<fork>
+currently unavailable. A true kernel C<fork()> 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<perlfork>). In the meantime, use C<system>, backticks, or piped
+filehandles to create subprocesses.
=item getpwent
=item kill
-In most cases, C<kill> kill is implemented via the CRTL's C<kill()>
+In most cases, C<kill> is implemented via the CRTL's C<kill()>
function, so it will behave according to that function's
documentation. If you send a SIGKILL, however, the $DELPRC system
service is called directly. This insures that the target
as a command procedure.
If LIST consists of the empty string, C<system> spawns an
-interactive DCL subprocess, in the same fashion as typiing
+interactive DCL subprocess, in the same fashion as typing
B<SPAWN> at the DCL prompt.
Perl waits for the subprocess to complete before continuing
execution in the current process. As described in L<perlfunc>,
the return value of C<system> is a fake "status" which follows
-POSIX semantics; see the description of C<$?> in this document
-for more detail. The actual VMS exit status of the subprocess
-is available in C<$^S> (as long as you haven't used another Perl
-function that resets C<$?> and C<$^S> in the meantime).
+POSIX semantics unless the pragma C<use vmsish 'status'> is in
+effect; see the description of C<$?> in this document for more
+detail.
=item time
according to the same rules the CRTL C<times()> routine.
Therefore, the "system time" elements will always be 0, since
there is no difference between "user time" and "system" time
-under VMS, and the time accumulated by subprocess may or may
+under VMS, and the time accumulated by a subprocess may or may
not appear separately in the "child time" field, depending on
whether L<times> keeps track of subprocesses separately. Note
especially that the VAXCRTL (at least) keeps track only of
subprocesses spawned using L<fork> and L<exec>; it will not
-accumulate the times of suprocesses spawned via pipes, L<system>,
+accumulate the times of subprocesses spawned via pipes, L<system>,
or backticks.
=item unlink LIST
C<unlink> will delete the highest version of a file only; in
order to delete all versions, you need to say
- 1 while (unlink LIST);
+
+ 1 while unlink LIST;
+
You may need to make this change to scripts written for a
Unix system which expect that after a call to C<unlink>,
no files with the names passed to C<unlink> will exist.
=item waitpid PID,FLAGS
-If PID is a subprocess started by a piped L<open>, C<waitpid>
-will wait for that subprocess, and return its final
-status value. If PID is a subprocess created in some other way
-(e.g. SPAWNed before Perl was invoked), or is not a subprocess of
-the current process, C<waitpid> will check once per second whether
-the process has completed, and when it has, will return 0. (If PID
-specifies a process that isn't a subprocess of the current process,
+If PID is a subprocess started by a piped C<open()> (see L<open>),
+C<waitpid> will wait for that subprocess, and return its final status
+value in C<$?>. If PID is a subprocess created in some other way (e.g.
+SPAWNed before Perl was invoked), C<waitpid> will simply check once per
+second whether the process has completed, and return when it has. (If
+PID specifies a process that isn't a subprocess of the current process,
and you invoked Perl with the C<-w> switch, a warning will be issued.)
-The FLAGS argument is ignored in all cases.
+Returns PID on success, -1 on error. The FLAGS argument is ignored
+in all cases.
=back
The following VMS-specific information applies to the indicated
"special" Perl variables, in addition to the general information
-in L<perlvar>. Where there is a conflict, this infrmation
+in L<perlvar>. Where there is a conflict, this information
takes precedence.
=over 4
by the global symbol table.. The characters following C<CLISYM_> are
significant when an element of C<%ENV> is set or deleted: if the
complete string is C<CLISYM_LOCAL>, the change is made in the local
-symbol table, otherwise the global symbol table is changed.
+symbol table; otherwise the global symbol table is changed.
=item Any other string
present only in some versions of the DECCRTL; check C<$Config{d_setenv}>
to see whether your copy of Perl was built with a CRTL that has this
function.)
-
+
When an element of C<%ENV> is set to C<undef>,
the element is looked up as if it were being read, and if it is
found, it is deleted. (An item "deleted" from the CRTL C<environ>
by saying
foreach my $key (qw[C-local keys you want promoted]) {
- my $temp = $ENV{$key}; # read from C-local array
- $ENV{$key} = $temp; # and define as logical name
+ my $temp = $ENV{$key}; # read from C-local array
+ $ENV{$key} = $temp; # and define as logical name
}
(You can't just say C<$ENV{$key} = $ENV{$key}>, since the
Perl optimizer is smart enough to elide the expression.)
+Don't try to clear C<%ENV> by saying C<%ENV = ();>, it will throw
+a fatal error. This is equivalent to doing the following from DCL:
+
+ DELETE/LOGICAL *
+
+You can imagine how bad things would be if, for example, the SYS$MANAGER
+or SYS$SYSTEM logicals were deleted.
+
At present, the first time you iterate over %ENV using
C<keys>, or C<values>, you will incur a time penalty as all
logical names are read, in order to fully populate %ENV.
You do need to be careful with the logicals representing process-permanent
files, such as C<SYS$INPUT> and C<SYS$OUTPUT>. The translations for these
logicals are prepended with a two-byte binary value (0x1B 0x00) that needs to be
-stripped off if you want to use it. (In previous versions of perl it wasn't
+stripped off if you want to use it. (In previous versions of Perl it wasn't
possible to get the values of these logicals, as the null byte acted as an
end-of-string marker)
low order 8 bits of C<$?> are always 0 under VMS, since the
termination status of a process may or may not have been
generated by an exception. The next 8 bits are derived from
-severity portion of the subprocess' exit status: if the
+the severity portion of the subprocess' exit status: if the
severity was success or informational, these bits are all 0;
-otherwise, they contain the severity value shifted left one bit.
+if the severity was warning, they contain a value of 1; if the
+severity was error or fatal error, they contain the actual
+severity bits, which turns out to be a value of 2 for error
+and 4 for fatal error.
+
As a result, C<$?> will always be zero if the subprocess' exit
status indicated successful completion, and non-zero if a
-warning or error occurred. The actual VMS exit status may
-be found in C<$^S> (q.v.).
-
-=item $^S
-
-Under VMS, this is the 32-bit VMS status value returned by the
-last subprocess to complete. Unlink C<$?>, no manipulation
-is done to make this look like a POSIX wait(5) value, so it
-may be treated as a normal VMS status value.
+warning or error occurred. Conversely, when setting C<$?> in
+an END block, an attempt is made to convert the POSIX value
+into a native status intelligible to the operating system upon
+exiting Perl. What this boils down to is that setting C<$?>
+to zero results in the generic success value SS$_NORMAL, and
+setting C<$?> to a non-zero value results in the generic
+failure status SS$_ABORT. See also L<perlport/exit>.
+
+The pragma C<use vmsish 'status'> makes C<$?> reflect the actual
+VMS exit status instead of the default emulation of POSIX status
+described above. This pragma also disables the conversion of
+non-zero values to SS$_ABORT when setting C<$?> in an END
+block (but zero will still be converted to SS$_NORMAL).
=item $|
=head2 SDBM_File
-SDBM_File works peroperly on VMS. It has, however, one minor
-difference. The database directory file created has a L<.sdbm_dir>
-extension rather than a L<.dir> extension. L<.dir> files are VMS filesystem
+SDBM_File works properly on VMS. It has, however, one minor
+difference. The database directory file created has a F<.sdbm_dir>
+extension rather than a F<.dir> extension. F<.dir> files are VMS filesystem
directory files, and using them for other purposes could cause unacceptable
problems.
=head1 Revision date
-This document was last updated on 26-Feb-2000, for Perl 5,
-patchlevel 6.
+This document was last updated on 01-May-2002, for Perl 5,
+patchlevel 8.
=head1 AUTHOR
-Charles Bailey <bailey@cor.newman.upenn.edu>
-Dan Sugalski <dan@sidhe.org>
+Charles Bailey bailey@cor.newman.upenn.edu
+Craig Berry craigberry@mac.com
+Dan Sugalski dan@sidhe.org
projects / p5sagit/p5-mst-13.2.git / blobdiff