[win32] integrate mainline

[p5sagit/p5-mst-13.2.git] / vms / perlvms.pod

diff --git a/vms/perlvms.pod b/vms/perlvms.pod
index c599e58..89c4bbf 100644 (file)
--- a/vms/perlvms.pod
+++ b/vms/perlvms.pod
@@ -329,7 +329,12 @@ undefined behavior (rarely, we hope):
     getgrnam, setgrent, endgrent, ioctl, link, lstat,
     msgctl, msgget, msgsend, msgrcv, readlink, semctl,
     semget, semop, setpgrp, setpriority, shmctl, shmget,
-    shmread, shmwrite, socketpair, symlink, syscall, truncate
+    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 may or may not be implemented, 
 depending on what type of socket support you've built into 
@@ -658,12 +663,20 @@ list logical names.  For instance, if you say
 
 Perl will print C<ONCE UPON A TIME THERE WAS>.
 
-The %ENV keys C<home>, C<path>,C<term>, and C<user>
-return the CRTL "environment variables" of the same
-names, if these logical names are not defined.  The
-key C<default> returns the current default device
+The key C<default> returns the current default device
 and directory specification, regardless of whether
-there is a logical name DEFAULT defined..
+there is a logical name DEFAULT defined.  If you try to
+read an element of %ENV for which there is no corresponding
+logical name, and for which no corresponding CLI symbol
+exists (this is to identify "blocking" symbols only; to
+manipulate CLI symbols, see L<VMS::DCLSym>) then the key
+will be looked up in the CRTL-local environment array, and
+the corresponding value, if any returned.  This lets you
+get at C-specific keys like C<home>, C<path>,C<term>, and
+C<user>, as well as other keys which may have been passed
+directly into the C-specific array if Perl was called from
+another C program using the version of execve() or execle() 
+present in recent revisions of the DECCRTL.
 
 Setting an element of %ENV defines a supervisor-mode logical 
 name in the process logical name table.  C<Undef>ing or 
@@ -675,6 +688,23 @@ 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.  It is not possible
 at present to define a search list logical name via %ENV.
+It is also not possible to delete an element from the
+C-local environ array.
+
+Note that if you want to pass on any elements of the
+C-local environ array to a subprocess which isn't
+started by fork/exec, or isn't running a C program, you
+can "promote" them to logical names in the current
+process, which will then be inherited by all subprocesses,
+by saying
+
+    foreach my $key (qw[C-local keys you want promoted]) {
+       my $temp = $ENV{$key}; # read from C-local array
+       $ENV{$key} = $temp;    # and define as logical name
+    }
+
+(You can't just say C<$ENV{$key} = $ENV{$key}>, since the
+Perl optimizer is smart enough to elide the expression.)
 
 At present, the first time you iterate over %ENV using
 C<keys>, or C<values>,  you will incur a time penalty as all
@@ -749,12 +779,23 @@ it's equivalent to calling fflush() and fsync() from C.
 
 =back
 
+=head1 Standard modules with VMS-specific differences
+
+=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
+directory files, and using them for other purposes could cause unacceptable
+problems.
+
 =head1 Revision date
 
-This document was last updated on 28-Feb-1996, for Perl 5, 
-patchlevel 2.
+This document was last updated on 26-Feb-1998, for Perl 5, 
+patchlevel 5.
 
 =head1 AUTHOR
 
-Charles Bailey  bailey@genetics.upenn.edu
+Charles Bailey  bailey@cor.newman.upenn.edu
 
+Last revision by Dan Sugalski  sugalskd@ous.edu