$SIG{expr}
             The associative array SIG  is  used  to  set  signal
             handlers for various signals.  Example:

                  sub handler {  # 1st argument is signal name
                       local($sig) = @_;
                       print "Caught a SIG$sig--shutting down\n";
                       close(LOG);
                       exit(0);
                  }

                  $SIG{'INT'} = 'handler';
                  $SIG{'QUIT'} = 'handler';
                  ...
                  $SIG{'INT'} = 'DEFAULT'; # restore default action
                  $SIG{'QUIT'} = 'IGNORE'; # ignore SIGQUIT

             The SIG array only contains values for  the  signals
             actually set within the perl script.