ulimit – get and set user limits  – only affects bash programs and those launched from bash

ulimit [options [limit]]     (-a show current settings)

-c     limits size of core dumps

-f    limits size of files created by shell

-n   limits number of open file descriptor

-u   limits number of processes a user can run

-t    limits CPU time in seconds

-v   sets virtual memory available to shell

 -s   sets maximum stack size

-d   limits programs data set size

-l   sets maximum size that can be locked in memory

-H,  -S  makes other options hard or soft limits