Restricting Users with ulimit in linux.

Oneway to limit users is by using the ulimit command that is part of the shell.
Typically ulimit commands are placed in /etc/profile so that each user who logsin will execute the commands and set limits on himself. Therefore decide what limits to place on your users and put ulimit commands into /etc/profile.

The most ulimit options are...

1. -a    Displays all limits 
2. -c     maximum core file size
3. -f      maximum file size
4. -t      maximum CPU time in sec
5. -n    maximum no of open files
6. -u    maximum no of processes

-v    maximum amount of virtual memory



This example displays the users limit and then changes the maximum number of open files..

Gspace$ ulimit -a |grep open