Your group support is not very useful, yet, because it
only checks the
 current group. 
 True, but group support wasn't really my prime objective at this point in
 time (see below). 
 
 That's what I figured.  Sorry to sound overly critical.  I should have
 framed my comments in a positive context.   
 
Hey, no problem.
Spurred on by your comments and the fact I unexpectedly found myself with a
little free time overnight, I have addressed the issues with the group
support in set_rtlimits.  Group and user name spaces are now treated
separately, with groupnames starting with a @ character.  Furthermore, a
user's supplementary group list is now scanned for a match (they are
correctly propagated to a setuid binary, at least under Linux), making the
group support more useful for people in general.  I also took the
opportunity to improve the clarity of some error messages.
Set_rtlimits 1.1.0 can be downloaded using the URL
  
http://www.physics.adelaide.edu.au/~jwoithe/set_rtlimits-1.1.0.tgz
Set_rtlimits is now also linked on my homepage at
    
http://www.physics.adelaide.edu.au/~jwoithe
in the "Linux things" section.
  Your program is quite useful and timely.  Given the
difficulty of
 patching and then configuring PAM, I expect very few users to use the
 new rlimits effectively until those changes have percolated down into
 widely-available distributions. 
Indeed, and there are some which won't use PAM at all.
  My comments were intended to encourage further
development of this
 useful program, not to come across as harsh and critical. 
No problem - sorry if I came across as annoyed.  Constructive comments and
suggestions are always welcome.
Another thing I'm pondering is adding support for setting the memlock limit
for selected binaries; this way a user doesn't have to be granted large
memlock limits in general just so they can run one or two apps which need
it.  If this happens I might rename set_rtlimits to set_rlimits since this
change would make it more general than just dealing with realtime limits.
Would this be useful for people?
Best regards
  jonathan