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[PATCH bleadperl] better VMS docs for $?, exit(), and system()

From:
Craig A. Berry
Date:
August 7, 2001 18:01
Subject:
[PATCH bleadperl] better VMS docs for $?, exit(), and system()
Message ID:
5.1.0.14.0.20010807155648.01ba3c98@exchi01
I think I've finally sorted out how all this works.  If anyone spots any 
errors, please let me know.


--- pod/perlport.pod;-0 Thu Aug  2 09:29:41 2001
+++ pod/perlport.pod    Tue Aug  7 19:53:34 2001
@@ -1527,6 +1527,17 @@
 
 Not implemented. (Plan9, Win32)
 
+=item exit EXPR
+
+=item exit
+
+Emulates UNIX exit() (which considers C<exit 1> to indicate an error) by
+mapping the C<1> to SS$_ABORT (C<44>).  This behavior may be overridden
+with the pragma C<use vmsish 'exit'>.  As with the CRTL's exit()
+function, C<exit 0> is also mapped to an exit status of SS$_NORMAL
+(C<1>); this mapping cannot be overridden.  Any other argument to exit()
+is used directly as Perl's exit status. (VMS)
+
 =item getsockopt SOCKET,LEVEL,OPTNAME
 
 Not implemented. (S<Mac OS>, Plan9)
@@ -1737,6 +1748,11 @@
 Does not automatically flush output handles on some platforms.
 (SunOS, Solaris, HP-UX)
 
+The return value is POSIX-like (shifted up by 8 bits), which only allows
+room for a made-up value derived from the severity bits of the native
+32-bit condition code (unless overridden by C<use vmsish 'status'>). 
+For more details see L<perlvms/$?>. (VMS)
+
 =item times
 
 Only the first entry returned is nonzero. (S<Mac OS>)
--- pod/perlvar.pod.-0  Sun Jul 29 12:29:06 2001
+++ pod/perlvar.pod     Tue Aug  7 16:56:25 2001
@@ -572,7 +572,7 @@
 
 Under VMS, the pragma C<use vmsish 'status'> makes C<$?> reflect the
 actual VMS exit status, instead of the default emulation of POSIX
-status.
+status; see L<perlvms/$?> for details.
 
 Also see L<Error Indicators>.
 
--- vms/perlvms.pod;-0  Mon Jul  9 09:11:33 2001
+++ vms/perlvms.pod     Tue Aug  7 19:53:33 2001
@@ -17,7 +17,7 @@
 We hope these notes will save you from confusion and lost 
 sleep when writing Perl scripts on VMS.  If you find we've 
 missed something you think should appear here, please don't 
-hesitate to drop a line to vmsperl@newman.upenn.edu.
+hesitate to drop a line to vmsperl@perl.org.
 
 =head1 Installation
 
@@ -486,7 +486,7 @@
 the subprocess before calling C<exec>.
 
 In general, the use of C<fork> and C<exec> to create 
-subprocess is not recommended under VMS; wherever possible, 
+subprocesses is not recommended under VMS; wherever possible, 
 use the C<system> operator or piped filehandles instead.
 
 =item getpwent
@@ -841,14 +841,26 @@
 generated by an exception.  The next 8 bits are derived from
 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.
+if the severity was warning, they contain a value of 1; if the
+severity was error or fatal error, they contain the actual
+severity bits, which turns out to be a value of 2 for error
+and 4 for fatal error.  
+
 As a result, C<$?> will always be zero if the subprocess' exit
 status indicated successful completion, and non-zero if a
-warning or error occurred.  
+warning or error occurred.  Conversely, when setting C<$?> in
+an END block, an attempt is made to convert the POSIX value
+into a native status intelligible to the operating system upon
+exiting Perl.  What this boils down to is that setting C<$?>
+to zero results in the generic success value SS$_NORMAL, and
+setting C<$?> to a non-zero value results in the generic
+failure status SS$_ABORT.  See also L<perlport/exit>.
 
 The pragma C<use vmsish 'status'> makes C<$?> reflect the actual 
-VMS exit status, instead of the default emulation of POSIX status 
-described above.
+VMS exit status instead of the default emulation of POSIX status 
+described above.  This pragma also disables the conversion of
+non-zero values to SS$_ABORT when setting C<$?> in an END
+block (but zero will still be converted to SS$_NORMAL).
 
 =item $|
 
@@ -871,10 +883,11 @@
 
 =head1 Revision date
 
-This document was last updated on 26-Feb-2000, for Perl 5, 
-patchlevel 6.
+This document was last updated on 7-Aug-2001, for Perl 5, 
+patchlevel 8.
 
 =head1 AUTHOR
 
 Charles Bailey  <bailey@cor.newman.upenn.edu>
+Craig Berry  <craigberry@mac.com>
 Dan Sugalski  <dan@sidhe.org>
[end of patch]




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