Actually it will work for regular CGI as well. The usecs won't hurt anything at all. I just decided to add it as an extra precaution because I do CGI and mod_perl.

For what you are doing, I would
1. If the user doesn't have a sessionID cookie generate a sessionID for the user and set the cookie with the sessionID
2. Use this as the file name. (Make sure to use Taint and check the sessionID for naughty characters.)
3. Open the sessionID named file and read/store you data.
4. Write a script to clean up old files and throw it in cron.

If you are really worried about filename collisions, write the files to a directory only used by this program.

-Lee

"To be civilized is to deny one's nature."