On Oct 23, 2013, at 12:56 AM, Shaji Kalidasan wrote:
> Dear Perlers
>
> Please throw some light on the $? variable
>
> I am trying to figure out how the internal structure (format) of $? variable.
> Please throw some light on this topic.
The content of $? is explained in the perlvar document. Type 'perldoc perlvar'
and search for 'CHILD_ERROR':
$CHILD_ERROR
$? The status returned by the last pipe close, backtick ("``")
command, successful call to "wait()" or "waitpid()", or from
the "system()" operator. This is just the 16-bit status word
returned by the traditional Unix "wait()" system call (or else
is made up to look like it). Thus, the exit value of the
subprocess is really ("$? >> 8"), and "$? & 127" gives which
signal, if any, the process died from, and "$? & 128" reports
whether there was a core dump.
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