I can't really help you on that specific question, but maybe I can clearify cron
and perl...
cron as like an automated task, that gets called and executed once a week, a day or a minute etc. Picture it like this. You tell your operating system you want a particular program be run automatically. Cron then starts the execution of that program when the time is come
Using this funktionality (on linux machines)
you could write a perl script that deletes everythig in the temp directory.
Perl, is a "scripting language". Which runs on quite some platforms (Linux, Windows NT...) and is normally used to write cgi programs running on internet servers. You might check out "www.perl.com"...