I'm working in an office nad so I cannot give root password to anyone in the office. So I have created a user in my linux which has some rights to work on machine. But i don't know how to give that user the right to shutdown or reboot the machine. Would anyone help me in this. thanx in advance

well the convoluted way i'd go about doing it is to find out where shutdown and halt are at using the whereis command (for me the ones to look at are in /sbin). anyway, create a group, add the users you want to be able to shutdown/halt to that group, use chgrp on those files to the name of your new shutdown group, and then chmod those files to allow exec permissions for group. that should do it. if you want to keep your new user for shutdown, you'll have to edit the sudo file. i guess man sudo for that.

edit: for me, the basic commands that you're used to using (/usr/bin/poweroff, /usr/bin/reboot, etc...) are just links to halt, shutdown, or consolehelper (which maybe just a redhat thing).

man sudo, man sudoers, man visudo

I have this line to let the users of my laptop do a poweroff without giving a password.
%users laptop = NOPASSWD: /sbin/poweroff

Is there a way to list all groups in linux ? I'm looking for a command that can perform such task.

I think it is dangerous giving permission to everyone in server as well. My method is:

- make a group called "logoff"
- change "halt" to group logoff (chown root:logoff halt)
- chmod 4750 halt

so root and people of group has permission to shut down the computer (halt -p)

(in fact I am not sure if the command work in linux, I am in bsd right now)