Interoperability UNIX and Java

[vik nuckchady]

Hi
I am trying to build an intranet using J2EE. However i was thinking of leavig the access control management to UNIX since it has a strong track record in terms of security. The idea is to let UNIX decide whether a user belonging to some group can have access to the document (object in question).
This idea derives from the possiblity of making system calls as in a CGI approach. i know this defeats some very important rules laid down by Sun.
i would really appreciate any criticism or ideas of how to go about.
Thanks in advance.
Regards Vik