post and write a html at the same time

If I understand correctly, what you want to do is to make your cgi create a HTML file, and then display it's contents on screen.

Just print the info into a html file and also into the browser (no file handle).

Something like this :

print "Content-type: text/html","\n\n";      # MIME header

print HTMLFILE $String;
print $String;

and repeat it this way for all the data in the file.

yes, you understood my question.
but any other solution? if i use your solution above, my cgi program is too long!

another idea is that you can create the html file then when that's done send a redirect to the broswer by sending a
"Location:<new http file>\n\n" as a http header.

i think this method is better though i haven't try out.