How can I run a system command and die if anything is written to STDERR?

Question

I\'m writing a Perl script which uses an external script. The external script must run from a specific directory so I found the following useful:

use IPC::System         


        

Answer 1

This is covered in the Perl FAQ.

Presuming test_app is a program that outputs one line to stdout and one line to stderr:

use IPC::Open3;
use Symbol 'gensym';

my($wtr, $rdr, $err);
$err = gensym;

my $pid = open3($wtr, $rdr, $err, 'test_app');

waitpid($pid, 0);
my $status = $? >> 8;

my $stdout = <$rdr>;
my $stderr = <$err>;

print "out output: $stdout\n";
print "err output: $stderr\n";

print "Exit code: $status\n";

EDIT: Per the request updated to include capturing the exit code. You could also have asked perldoc IPC::Open3 which says

waitpid( $pid, 0 );
my $child_exit_status = $? >> 8;

And which you should read anyway for its cautions and caveats.