catching errors??

[John Smith]

guys,
how'd i customize 'mapserv(): Web application error' and 'msDrawMap():
Image handling error'? in the first case only mapserver fails. in the
second postgresql fails first then mapserver. anyway using cgi so
catching error inside template isn't useful since template gets
bypassed on error. what i'd really like is log error and display
message from log.
jzs