Question

I want to execute an external command from within my Perl script, putting the output of both stdout and stderr into a $variable of my choice, and to get the command’s exit code into the $? variable.

I went through solutions in perlfaq8 and their forums, but they’re not working for me. The strange thing is that I don’t get the output of sdterr in any case, as long as the exit code is correct.

I’m using Perl version 5.8.8, on Red Hat Linux 5.

Here’s an example of what I’m trying:

my $cmd="less";
my $out=`$cmd 2>&1`;

or

my $out=qx($cmd 2>&1);

or

open(PIPE, "$cmd 2>&1|");

When the command runs successfully, I can capture stdout.

I don’t want to use additional capture modules. How can I capture the full results of the external command?

Answer 1

Actually, the proper way to write this is:

#!/usr/bin/perl
$cmd = 'lsss';  
my $out=qx($cmd 2>&1);
my $r_c=$?;
print "output was $out\n";
print "return code = ", $r_c, "\n";

You will get a ‘0’ if no error and ‘-1’ if error.