% perl sample9.pl
[ERROR] error message
[FATAL] fatal message

% perl sample9.pl --logfile mylog.output
[ERROR] error message
[FATAL] fatal message

% cat mylog.output && rm mylog.output
2008/08/06 13:37:24 main error message
2008/08/06 13:37:24 main fatal message

% perl sample9.pl --logfile 'mylog.output|%d %m%n'
[ERROR] error message
[FATAL] fatal message

% cat mylog.output && rm mylog.output
2008/08/06 13:41:50 error message
2008/08/06 13:41:50 fatal message