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
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
-specification. Filenames are, of course, still case-
-insensitive. For consistency, most Perl routines return
-filespecs 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.)
+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
+VMS file specification). There are a set of functions
+provided in the C<VMS::Filespec> package for explicit
+interconversion between VMS and Unix syntax; its
+documentation provides more details.
+
+Filenames are, of course, still case-insensitive. For
+consistency, most Perl routines return filespecs 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,
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>,
them in double-quotes on the command line, since the CRTL
downcases all unquoted strings.
+=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> switch is present I<and> the script name does
after the Perl program is compiled, but before it has
run. It does not create a core dump file.
+=back
+
=head1 Perl functions
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, 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,
getsockopt, listen, recv, select(system call)*,
send, setsockopt, shutdown, socket
+=over 4
=item File tests
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$spawn()>, any valid DCL command string
+may be specified.
+
=item binmode FILEHANDLE
-The C<binmode> operator has no effect under VMS. It will
-return TRUE whenever called, but will not affect I/O
-operations on the filehandle given as its argument.
+The C<binmode> operator will attempt to insure that no translation
+of carriage control occurs on input from or output to this filehandle.
+Since this involves reopening the file and then restoring its
+file position indicator, if this function returns FALSE, the
+underlying filehandle may no longer point to an open file, or may
+point to a different position in the file than before C<binmode>
+was called.
+
+Note that C<binmode> is generally not necessary when using normal
+filehandles; it is provided so that you can control I/O to existing
+record-structured files when necessary. You can also use the
+C<vmsfopen> function in the VMS::Stdio extension to gain finer
+control of I/O to files and devices with different record structures.
=item crypt PLAINTEXT, USER
Also, negative signal values don't do anything special under
VMS; they're just converted to the corresponding positive value.
+=item qx//
+
+See the entry on C<backticks> above.
+
=item select (system call)
If Perl was not built with socket support, the system call
of the empty string, C<system> spawns an interactive DCL subprocess,
in the same fashion as typiing B<SPAWN> at the DCL prompt.
Perl waits for the subprocess to complete before continuing
-execution in the current process.
+execution in the current process. As described in L<perlfunc>,
+the return value of C<system> is a fake "status" which follows
+POSIX semantics; see the description of C<$?> 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
+
+The value returned by C<time> is the offset in seconds from
+01-JAN-1970 00:00:00 (just like the CRTL's times() routine), in order
+to make life easier for code coming in from the POSIX/Unix world.
=item times
The FLAGS argument is ignored in all cases.
+=back
+
=head1 Perl variables
+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
+takes precedence.
+
+=over 4
+
=item %ENV
Reading the elements of the %ENV array returns the
$ Define STORY once,upon,a,time,there,was
$ perl -e "for ($i = 0; $i <= 6; $i++) " -
- _$ -e "{ print $ENV{'foo'.$i},' '}"
+ _$ -e "{ print $ENV{'story;'.$i},' '}"
Perl will print C<ONCE UPON A TIME THERE WAS>.
replace the logical name just deleted. It is not possible
at present to define a search list logical name via %ENV.
+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.
+Subsequent iterations will not reread logical names, so they
+won't be as slow, but they also won't reflect any changes
+to logical name tables caused by other programs. The C<each>
+operator is special: it returns each element I<already> in
+%ENV, but doesn't go out and look for more. Therefore, if
+you've previously used C<keys> or C<values>, you'll see all
+the logical names visible to your process, and if not, you'll
+see only the names you've looked up so far. (This is a
+consequence of the way C<each> is implemented now, and it
+may change in the future, so it wouldn't be a good idea
+to rely on it too much.)
+
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.
-=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
the underlying RMS buffers for a file). In other words,
it's equivalent to calling fflush() and fsync() from C.
+=back
+
=head1 Revision date
This document was last updated on 28-Feb-1996, for Perl 5,
projects / p5sagit/p5-mst-13.2.git / blobdiff