yes I do understand but it is not working. In other words when cat
/tmp/foo fails the blah blah blah is not ran.
What I do not understand is the notes from the cookbook specifically $exit_value =
$? >> 8;
How would I code this so that my if works b/c it sounds like to me as the notes say
the return code is two 8
bit values in one 16 bit number.
thank you ,
Derek B. Smith
OhioHealth IT
UNIX / TSM / EDM Teams
"Wiggins d Anconia" <[EMAIL PROTECTED]>
08/27/2004 04:12 PM
To: [EMAIL PROTECTED], [EMAIL PROTECTED]
cc:
Subject: Re: system call
>
> All,
>
> I want to capture the exit value of a system call. How can I do this?
> My code is:
>
> system ( " cat /tmp/foo" );
> if ( $? == 0 ) {
>
> blah blah blah
> }
>
>
> I read the cookbook and it says :
>
> Both wait and waitpid return the process ID that they just reaped and
set $? to the wait status of the defunct process. This status is
actually two
> 8-bit values in one 16-bit number. The high byte is the exit value of
the
> process. The low 7 bits represent the number of the signal that killed
the
> process, with the 8th bit indicating whether a core dump occurred.
Here's
> one way to isolate those values:
> $exit_value = $? >> 8;
> $signal_num = $? & 127;
> $dumped_core = $? & 128;
>
So what don't you understand? C<$?> will be set automatically, using the
above code you can isolate the exit value as $exit_value. You have
seemingly answered your own question.
The
if ($? == 0)
Is actually not completely correct, it will only be correct on
(standard) success, better to use the 3 lines of code you provided, and
check the specific exit value.
http://danconia.org
