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                   @args = ("command", "arg1", "arg2");
                   system(@args) == 0
...
                   else {
                       printf "child exited with value %d\n", $? >> 8;
                   }

#!/usr/bin/perl

...

  return $error ;
}

    $ret = check_cmd(cmd      => [$config{cvs_command},'login'],
                     onerror  => 'none',
...
    unless ($ret == 0) {
      # do something...
    }