during the build process for the Perl extension.
By default, the shareable image for an extension is placed
-in the F<[.Lib.Auto.>I<Arch>.I<Extname>F<]> directory of 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>, followed by the Perl version number, and I<Extname>
-is the name of the extension, with each C<::> translated to C<.>).
+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<Extname>F<]> subdirectory of one of
- the directories in C<@INC>, or
+ - 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
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, crypt*, defined, delete,
die, do, dump*, each, endpwent, eof, eval, exec*,
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,
+ qx//*, quotemeta, rand, read, readdir, redo, ref, rename,
require, reset, return, reverse, rewinddir, rindex,
rmdir, s///, scalar, seek, seekdir, select(internal),
select (system call)*, setpwent, shift, sin, sleep,
your C compiler's F<stat.h>, 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<lib$spawn()>, any valid DCL command string
+may be specified.
+
=item binmode FILEHANDLE
The C<binmode> operator will attempt to insure that no translation
Also, negative signal values don't do anything special under
VMS; they're just converted to the corresponding positive value.
+=item qx//
+
+See the entry on C<backticks> above.
+
=item select (system call)
If Perl was not built with socket support, the system call
of the empty string, C<system> spawns an interactive DCL subprocess,
in the same fashion as typiing B<SPAWN> at the DCL prompt.
Perl waits for the subprocess to complete before continuing
-execution in the current process.
+execution in the current process. As described in L<perlfunc>,
+the return value of C<system> is a fake "status" which follows
+POSIX semantics; see the description of C<$?> 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).
=item time
were entirely uppercase, regardless of the case actually
specified in the Perl expression.
-=item $?
-
-Since VMS status values are 32 bits wide, the value of C<$?>
-is simply the final status value of the last subprocess to
-complete. This differs from the behavior of C<$?> under Unix,
-and under VMS' POSIX environment, in that the low-order 8 bits
-of C<$?> do not specify whether the process terminated normally
-or due to a signal, and you do not need to shift C<$?> 8 bits
-to the right in order to find the process' exit status.
-
=item $!
The string value of C<$!> is that returned by the CRTL's
corresponding VMS message string, as retrieved by sys$getmsg().
Setting C<$^E> sets vaxc$errno to the value specified.
+=item $?
+
+The "status value" returned in C<$?> is synthesized from the
+actual exit status of the subprocess in a way that approximates
+POSIX wait(5) semantics, in order to allow Perl programs to
+portably test for successful completion of subprocesses. The
+low order 8 bits of C<$?> are always 0 under VMS, since the
+termination status of a process may or may not have been
+generated by an exception. The next 8 bits are derived from
+severity portion of the subprocess' exit status: if the
+severity was success or informational, these bits are all 0;
+otherwise, they contain the severity value shifted left one bit.
+As a result, C<$?> 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.
+
=item $|
Setting C<$|> for an I/O stream causes data to be flushed
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