Elie De Brauwer wrote:
> Hello list,
Hello,
> I recently encountered a small oddity. Suppose I have a process A:
>
> #!/usr/bin/perl
>
> use strict;
>
> print "Hello \n";
> sleep 1;
> print "Goodbye\n";
> exit 9;
>
> Simply shows some out and gives a certain exit code. A second process,
> simply calls fork, execs the child in a process and waits for the child
> in the other process. In Perl this can look like this:
>
> my $cmd = "/home/user/proces.pl";
> my $pid = fork();
> if($pid == 0){
> print "Hi I'm a child\n";
> exec $cmd or die "Failed to run $cmd\n";
> }else{
> print "Hi I'm a parent waiting for child with PID: $pid\n";
> my $ret = waitpid($pid,0);
> print "$pid exited with code ". ($?>>8) ."\n";
> }
>
> The oddity i located in the last line. It seemd that I had to divide $?
> by 256 (or shift over 8 positions to the right) to get the correct exit
> code. So my question is:
> a) Is there an other way to wait for a child to die and get the exit code
> b) Can someone explain the odd behaviour of the exit code ?
Have you read the perl documentation on the functions and variables you are
using?
perldoc perlipc
perldoc perlvar
perldoc -f fork
perldoc -f exec
perldoc -f waitpid
John
--
use Perl;
program
fulfillment
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