At least on a Unix box, system() will return the exit status of the system call:

$x = system("echo y");
$x = $x/255; #set $x to actual exit value
$y = system("blahblah");
$y = $y/255; #set $y to actual exit value
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results in $x set to 0 and $y set to 256 (as long as there's no executable called "blahblah" in $PATH).