diff options
Diffstat (limited to 'vms/perlvms.pod')
| -rw-r--r-- | vms/perlvms.pod | 56 |
1 files changed, 43 insertions, 13 deletions
diff --git a/vms/perlvms.pod b/vms/perlvms.pod index e065b08baa..830ff613d5 100644 --- a/vms/perlvms.pod +++ b/vms/perlvms.pod @@ -300,7 +300,7 @@ 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*, @@ -310,7 +310,7 @@ Perl functions were implemented in the VMS port of Perl 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, @@ -375,6 +375,13 @@ only, and then manually check the appropriate bits, as defined by 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$spawn()>, any valid DCL command string +may be specified. + =item binmode FILEHANDLE The C<binmode> operator will attempt to insure that no translation @@ -509,6 +516,10 @@ supervisor-mode images like DCL.) Also, negative signal values don't do anything special under VMS; they're just converted to the corresponding positive value. +=item qx// + +See the entry on C<backticks> above. + =item select (system call) If Perl was not built with socket support, the system call @@ -537,7 +548,12 @@ valid DCL command string may be specified. If LIST consists of the empty string, C<system> spawns an interactive DCL subprocess, in the same fashion as typiing B<SPAWN> at the DCL prompt. Perl waits for the subprocess to complete before continuing -execution in the current process. +execution in the current process. As described in L<perlfunc>, +the return value of C<system> is a fake "status" which follows +POSIX semantics; see the description of C<$?> 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 @@ -679,16 +695,6 @@ 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 @@ -710,6 +716,30 @@ is the value of vaxc$errno, and its string value is the corresponding VMS message string, as retrieved by sys$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 |