DBMS_File Equivalent?

Can a trigger, written in plperl, write to the OS when it fires?  I want
to write a trigger, in plperl, that builds an RSS feed file with each
row that gets added to one of my tables.  My database (8 rc 3, on Redhat
9) seems to choke (terminated on signal 11) each time I try to write to
the OS - I would imagine because it's a major security threat to have
the DB blindly writing to the filesystem.  I guess what I really need is
something like dbms_file in Oracle, where one predefines where the DB is
allowed to read and write files.  Can this be done with Postgres?

Dunc