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'
+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
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. <CE<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.
+In both cases, 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
a device and directory; otherwise, device and directory
You may also use backticks to invoke a DCL subprocess, whose
output is used as the return value of the expression. The
-string between the backticks is passed directly to lib$spawn
-as the command to execute. In this case, Perl will wait for
-the subprocess to complete before continuing.
+string between the backticks is handled as if it were the
+argument to the C<system> operator (see below). In this case,
+Perl will wait for the subprocess to complete before continuing.
=head1 PERL5LIB and PERLLIB
-The PERL5LIB and PERLLIB logical names work as documented L<perl>,
+The PERL5LIB and PERLLIB logical names work as documented
in L<perl>,
except that the element separator is '|' instead of ':'. The
directory specifications may use either VMS or Unix syntax.
If the call to C<exec> does not follow a call to C<fork>, it
will cause Perl to exit, and to invoke the command given as
an argument to C<exec> via C<lib$do_command>. If the argument
-begins with a '$' (other than as part of a filespec), then it
+begins with '@' or '$' (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.
+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
=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 $DELPRC system
service is called directly. This insures that the target
The C<system> operator creates a subprocess, and passes its
arguments to the subprocess for execution as a DCL command.
Since the subprocess is created directly via C<lib$spawn()>, any
-valid DCL command string may be specified. If LIST consists
-of the empty string, C<system> spawns an interactive DCL subprocess,
-in the same fashion as typiing B<SPAWN> at the DCL prompt.
+valid DCL command string may be specified. If the string begins with
+'@', it is treated as a DCL command unconditionally. Otherwise, if
+the first token contains a character used as a delimiter in file
+specification (e.g. C<:> or C<]>), an attempt is made to expand it
+using a default type of F<.Exe> and the process defaults, and if
+successful, the resulting file is invoked via C<MCR>. This allows you
+to invoke an image directly simply by passing the file specification
+to C<system>, a common Unixish idiom. 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.
+
+If LIST consists of the empty string, C<system> spawns an
+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
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);
+
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
+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. 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 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<$Config{d_setenv}>
to see whether your copy of Perl was built with a CRTL that has this
function.)
-
+
When an element of C<%ENV> is set to C<undef>,
the element is looked up as if it were being read, and if it is
found, it is deleted. (An item "deleted" from the CRTL C<environ>
(You can't just say C<$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<$?> are always 0 under VMS, since the
termination status of a process may or may not have been
generated by an exception. The next 8 bits are derived from
-severity portion of the subprocess' exit status: if the
+the severity portion of the subprocess' exit status: if the
severity was success or informational, these bits are all 0;
otherwise, they contain the severity value shifted left one bit.
As a result, C<$?> will always be zero if the subprocess' exit
=item $^S
Under VMS, this is the 32-bit VMS status value returned by the
-last subprocess to complete. Unlink C<$?>, no manipulation
+last subprocess to complete. Unlike 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.
=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-1998, for Perl 5,
-patchlevel 5.
+This document was last updated on 26-Feb-2000, for Perl 5,
+patchlevel 6.
=head1 AUTHOR
-Charles Bailey bailey@cor.newman.upenn.edu
-
-Last revision by Dan Sugalski sugalskd@ous.edu
+Charles Bailey <bailey@cor.newman.upenn.edu>
+Dan Sugalski <dan@sidhe.org>
https://perl5.git.perl.org / perl5.git / blobdiff