my $output = system('cleartool', 'lsco', '-r', '-brt', $stream, '-fmt', '%En\t%u\n');

##</code><code>##

my $output = `cleartool lsco -r -brt $stream -fmt "%En\\t%u\\n"`;

##</code><code>##

my $output = `cleartool lsco -r -brt $stream -fmt '%En\\t%u\\n'`;