diff options
Diffstat (limited to 'vms/perlvms.pod')
| -rw-r--r-- | vms/perlvms.pod | 35 |
1 files changed, 30 insertions, 5 deletions
diff --git a/vms/perlvms.pod b/vms/perlvms.pod index 4aa68008d5..89c4bbf623 100644 --- a/vms/perlvms.pod +++ b/vms/perlvms.pod @@ -663,12 +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 @@ -680,6 +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 |