Spawned process exit status

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

I'm trying to capture the exit status of a spawned process. The script conf.pl executes and I inserted a fault, so when all is well it returns 0 and with fault it returns 13
$? returns 0 even it there is a fault. Any thoughts?

use Run;
my $cfg_test = "conf_ini";
my $cfg_stat = "fresh";

my $system_call = '/test/conf.pl';
$pid = spawn $system_call, $cfg_test, $cfg_stat  or die "spawn: $!";
push @pids, $pid;
      
    my $num_proc1 = @pids;
       while ($num_proc1) {
    for ( my $i=0; $i< @pids; $i++) {
     waitpid($pids[$i],0);
     $num_proc1 --;
         $pid --;
        }
    print "DOES THIS -- $? -- CAPTURE ANYTHING\n";

  if ( $system_call >> 8, 0,       'Normal exit' ){
    print "good\n";}
  if( $exit >> 8, 42,             'Non-zero exit' ){
    print "bad\n";}
        
    if ($? == 13) {
    print "failed: $!\n";
    }
    elsif ($? & 127) {
      print "$pid died with signal $?\n",
        ($? & 127),  ($? & 128) ? 'with' : 'without';
    }
    elsif ($? > 0) {
      print "$pid died with signal $?\n";    
    }
    else {
        print "$pid exited with value $?\n", $? >> 8;
    }
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Comment on Spawned process exit status Download Code

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Re: Spawned process exit status by VSarkiss (Monsignor) on Jun 22, 2005 at 15:49 UTC
What system are you running this on? It can make a big difference. As an aside, this looks extremely suspicious.... `my $system_call = '/test/conf.pl'; # # later ... # if ( $system_call >> 8, 0, 'Normal exit' ){ print "good\n";}` [download] Besides shifting a string, that `if` isn't testing what you probably think it's testing.... Do not rebuke them with harsh words ... but rather lead them gently - with URLs - so that they may learn wisdom.	[reply] [d/l] [select]
Re^2: Spawned process exit status by Anonymous Monk on Jun 22, 2005 at 17:00 UTC
I'm running RH9. Perl version is 5.8.0	[reply]
Re: Spawned process exit status by waswas-fng (Curate) on Jun 22, 2005 at 16:45 UTC
Run and spawn exec a process in background mode. It only returns error codes for the exec return of the process -- not the result exit code. Use system() to get the exit code. from the perldoc for system: `Because system() and backticks block SIGINT and SIGQUIT, killing the p +rogram they're running doesn't actually interrupt your program. @args = ("command", "arg1", "arg2"); system(@args) == 0 or die "system @args failed: $?" You can check all the failure possibilities by inspecting $? like this +: $exit_value = $? >> 8; $signal_num = $? & 127; $dumped_core = $? & 128;` [download] -Waswas	[reply] [d/l]
Re^2: Spawned process exit status by Anonymous Monk on Jun 22, 2005 at 19:45 UTC
I made the changes and still I get the same. The script exits with an error code of 13 and $? reports back with 0. `@args = ("/test/conf.pl", $cfg_test, $cfg_stat ); system(@args) == 0 or die "system @args failed: $?"; $exit_value = $? >> 8; $signal_num = $? & 127; $dumped_core = $? & 128; print "EXIT VALUE = $exit_value\n"; print "SIGNAL = $signal_num\n"; print "CORE = $dumped_core\n";` [download]	[reply] [d/l]
Re^3: Spawned process exit status by waswas-fng (Curate) on Jun 23, 2005 at 16:16 UTC
That is because it never gets to your print "EXIT VALUE.. line when there is a non 0 exit on the conf.pl script. You explicitly tell it to die and spit out the unprocessed error held in $?. `What do you think this line does? system(@args) == 0 or die "system @args failed: $?";` [download] -Waswas	[reply] [d/l]