My guess is that the user your web-server is running as (nobody or www-data, most likely) doesn't have the proper permissions to do anything to your test directory. If you chmod 777 it from your command line, then the script ought to work from a browser.

Note, perl itself has a rmdir command, although you'd have to clear out the directory first (using File::Find or something.)

Huh? I thought you said the script ran fine from the command line, therefore I would hope that you somehow have permissions to play around with the test directory.

Nevertheless, a second thing you might check is to make sure that rm is in the script's path. Better yet, use a full path in your system call.

Have you checked the server's error log? What (if anything) does it say?