Generally speaking it means that within the program there is a line that says exit(255). Keep in mind that on unix systems exit codes are 8 bits, so if you think that your code isn't throwing that exit code because you grepped all the code for exit(255) and didn't find anything, it may be that you didn't look hard enough...

[jason@dev]$ perl -e 'exit -1';
[jason@dev]$ echo $?
255
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all of the non null exit statements within the script are preceeded by a write to an error log, and none mention the value 255 (or even -1) I don't see anything written to the error log so I assume that PERL itself is setting that exit code... -Stuart.

One possibility that I came across is dividing by zero.

I assume this is most likely caused by a die statement in your script:

$ perl -le 'die'
Died at -e line 1.
$ echo $?
255
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I tend to agree. There is no 'die' statement in the whole script so I suspect that the OS (Windows 2000 server) tries and fails to run the PERL script and returns the value 255. -Stuart.

There is no 'die' statement in the whole script

The thing is that there doesn't have to be a die statement or an explicit exit(255) in the script to get an exit value of 255. But something must be setting that value. As a (somewhat ridiculous) example, if you have a C compiler you could compile the following C program into 'try.exe':

int main(int argc, char * argv[])
{
 return 255;
}
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And then you could run the following perl script:

use warnings;
my $ret = system("try.exe");
print $ret >> 8, "\n", $? >> 8, "\n";
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You would find that produces as output:

255
255
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In that perl script, there's no die(), no mention of "255" and, in fact, nothing even failed - yet the 8 high bits of $? were set. (Hopefully, you don't have an executable that's running successfully and returning 255.)

How do you find out what the exit code is ? Is there a 'print $exitcode;' in the script ? ... or a 'print $? >> 8;' ? ... If we know the means by which you are being made aware of the exit value, then that might help with our speculations.

Cheers,
Rob

Try with:

$SIG{$_} = sub { exit 42; } for keys %SIG;
END            { exit 42; }
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If, with that change, the code keeps on returning 255 sometimes, you know that the cause is not in the code. Don't forget to remove it afterwards!

I'm not sure if this is relevant, but check the following node:

Re: system command erroneously states 'can't spawn <executable>'

You have an example of capturing the pseudo-signal __DIE__

See perldoc -f die, to see the posible exit codes (one of them is 255)

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oscar@toreyes-i7:~/WIP/perl/gestion_DIE$ cat prueba.pl 
use diagnostics;
use strict;

sub mensaje() { print "OJO !!!! Este script se ha muerto por la ejecuc
+ión de die()\n"; }

# Instalar manejador en caso de ejecuarse un die()
$SIG{__DIE__} = \&mensaje;

my $refFake = 'pepe';
print $refFake->{'lolo'}; # Aqui se genera el error
print "Me moriré antes de mostrar esta linea\n";

oscar@toreyes-i7:~/WIP/perl/gestion_DIE$ perl prueba.pl 
OJO !!!! Este script se ha muerto por la ejecución de die()
Can't use string ("pepe") as a HASH ref while "strict refs" in use at 
+prueba.pl line 10.

oscar@toreyes-i7:~/WIP/perl/gestion_DIE$ echo $?
255
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Another example:

oscar@toreyes-i7:~/WIP/perl/gestion_DIE$ cat prueba2.pl 
use diagnostics;
use strict;
use Data::Dumper;

sub mensaje() { print "OJO !!!! Este script se ha muerto por la ejecuc
+ión de die()\n"; }


                   sub handler {   # 1st argument is signal name
                       # En caso de una "unhandled excepcion" como la 
+generada
                       # por die(), @_ parece que es el mensaje de err
+or en vez
                       # del identificador de una señal real.
                       my($sig) = @_;
                       print "Dumper(\$sig): ", Dumper($sig);
                       if ($sig)
                       {
                           print "sig:", $sig, "\n";
                           print "Caught a SIG$sig--shutting down\n";
                       }
                       else
                       {
                           print "sig no tiene un valor de señal\n";
                       }
                       ## exit(0);
                       }


# Instalar manejador en caso de ejecutarse un die()
# $SIG{__DIE__} = \&mensaje;
$SIG{__DIE__} = \&handler;

my $refFake = 'pepe';
print $refFake->{'lolo'}; # Aqui se genera el error
print "Me moriré antes de mostrar esta linea\n";

oscar@toreyes-i7:~/WIP/perl/gestion_DIE$ echo $?
255
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