I have a need to obtain an exclusive lock on the shadow, group, and passwd files so that any process trying to modify these files will be blocked/denied until the lock is removed. I am not extremelly familiar with SuSE internals and etc.. I want to temporarily lock these files from either a perl of C program, preferably perl. It would take me many lines to explain line, but I simply need to lock these files so that no other process may modify them. (This lock would be held for a very short amount of time, but the process obtaining this lock is no where near atomic) These are clinical systems reponsisble for monitoring life support equipment among other things, so a 'jerry-rig' approach will not suffice. I need a 100%, rock solid way of this locking this file. Can anyone lead me in the right direction? Thanks CC