I need some help with browser output in ruby cgi - cgi.rb

[Professor Chen]

Whenever I try to send out some output in CGI my scripts generates an
error 500 with
-
Error message:
malformed header from script. Bad header=.: dblist.cgi
-

I am not really sure how to output text with the cgi.pre,
CGI::escapeHTML functions etc. Is there some guide to doing those
things right?

PS. Is there some way I can the cgi to send the actual ruby error
messages as part of the error 500 output?