Das Pod zu CGI.pm sagt dazu:
Quote The temporary directory is selected using the following algorithm:
1. if the current user (e.g. "nobody") has a directory named
"tmp" in its home directory, use that (Unix systems only).
2. if the environment variable TMPDIR exists, use the location
indicated.
3. Otherwise try the locations /usr/tmp, /var/tmp, C:\temp,
/tmp, /temp, ::Temporary Items, and \WWW_ROOT.
Das Setzen von $ENV{TMPDIR} an einer fruehen Stelle sollte also ausreichen. Das periodische Loeschen von TMPDIR per cronjob o.ae. ist natuerlich die bessere Loesung.