Perl fork process using open3

Question

I have a perl script in which I am forking a child process. Here is what I am doing:

my $pid = fork;

if($pid) {
# parent 
waitpid($pid, 0);
}
else {
exec("some other script X.pl");
}

Now, I wanted to capture the error of X.pl to display in my script. But as I understand this is not possible suing exec.

What are the other options I have?

How can I use open3 in my case?

Thanks!

Answer 1

If what you are looking for is just the return value of X.pl you can use

my $returnValue = $?>>8;

See and http://perldoc.perl.org/functions/system.html for more Information. By the way, if all your parent does is wait for the child, using system is probably better than fork and exec by Hand.

edit:

To capture STDOUT you can use

my $output = qx/X.pl/;

instead of forking and exec. This will still alow you to inspect $? for the return values. To not have perl interpolate the stuff in the command you can use also use qx'command' to pass the command to the System without changing anything. If you want your parent to do stuff while waiting for X.pl but still want return value and Output of X.pl i would suggest looking into expect. http://search.cpan.org/~rgiersig/Expect-1.15/Expect.pod