Capture STDOUT and STDERR of external command

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The executed script may have a huge output which ended up filling a variable when using IO::Capture from CPAN but that variable was never used.

Here is my solution capturing standard error and the external command's exit code but ignoring standard output:

use IPC::Open3 qw(open3);use Symbol qw(gensym);use Fcntl;use POSIX ":sys_wait_h";
sub capture_exec {
	# Create handles and launch child task	my ($wtr, $rdr);	my $err = gensym;	my $pid = open3($wtr, $rdr, $err, @_);	close $wtr;    # Child won't expect STDIN
	# Set child's STDOUT and STDERR to non-blocking mode.	for my $fh ($rdr, $err) {		my $flags = '';		fcntl($fh, F_GETFL, $flags)		  or die "Couldn't get flags for HANDLE : $!\n";		$flags |= O_NONBLOCK;		fcntl($fh, F_SETFL, $flags)		  or die "Couldn't set flags for HANDLE: $!\n";	}
	# Prepare vectors for select	my $rin = '';	vec($rin, fileno($rdr), 1) = 1;	vec($rin, fileno($err), 1) = 1;
	# Prepare STDERR buffer	my $errors;
	while (1) {
		# Wait until the child has data to read for us or 1 sec. timeout		my $rout;		if (select($rout = $rin, undef, undef, 1)) {			my $buffer;    # Buffer for reading one data block
			# Discard any STDOUT data			while (sysread($rdr, $buffer, 65535) == 65535) { }    # Read 64k blocks as long as we get 64k
			# Read STDERR 64k blocks and push then onto the STDERR buffer			while (1) {				sysread($err, $buffer, 65535);				$errors .= $buffer;				last if length($buffer) < 65535;			}		}
		# Clean up child process zombie(s)		waitpid -1, WNOHANG;
		last unless kill 0, $pid;    # Child is still running	}
	return \$errors, $? >> 8;}