Because system() and backticks block SIGINT and SIGQUIT, killing the program they're running doesn't actually interrupt your program.

    @args = ("command", "arg1", "arg2");
    system(@args) == 0
         or die "system @args failed: $?"

Here's a more elaborate example of analysing the return value from system() on a Unix system to check for all possibilities, including for signals and core dumps.

    $rc = 0xffff & system @args;
    printf "system(%s) returned %#04x: ", "@args", $rc;
    if ($rc == 0) {
        print "ran with normal exit\n";
    }
    elsif ($rc == 0xff00) {
        print "command failed: $!\n";
    }
    elsif ($rc > 0x80) {
        $rc >>= 8;
        print "ran with non-zero exit status $rc\n";
    }
    else {
        print "ran with ";
        if ($rc &   0x80) {
            $rc &= ~0x80;
            print "core dump from ";
        }
        print "signal $rc\n"
    }
    $ok = ($rc != 0);

When the arguments get executed via the system shell, results will be subject to its quirks and capabilities. See `STRING` for details.