Program to renice jobs

[Andrew Gunstensen]

Is there a good method of renicing jobs automatically once they
have exceeded some CPU time limit?  My problem is that we
have a large number of (relatively UNIX-clueless) users who
tend to run largish background jobs on our Sun network 
at niceness 0. 
This noticeably degrades interactive performance.  So we
would like to be able to run some program/shell script which
would check running jobs and if they have more than (say)
15 minutes CPU time and (say) they are not the X server (or
other jobs which we will allow to use as much time as they
like) then renice them down to some lower priority level.

Any thoughts on this?  Is it even desirable to do this?

Thanks for any info.

--
Andrew Gunstensen                                         _  /\
Rm 54-616, MIT, Cambridge, MA 02139, (617)-253-3384       \'o.O'     Bill
Internet: andrew at segovia.mit.edu                          =(___)=    Rules
                                                             U
      Data?  I don't need no stinkin' data!                      ack!