Howto: Linux kill and logout users

Yet another newbie question that suggests people love to kill and show their power to rest of the world ;)

Task: How to halt/stop user called didi

Type the skill command as follows:
# skill -STOP -u didi

You muse be root to stop other users.

Task: How to resume already halted user called didi

Send CONT single to user didi, type the following command:
# skill -CONT -u didi

Task: How to kill and logout user called didi

You can send KILL single, type the following command:
# skill -KILL -u didi

Task: Kill and logout all users

The ultimate command to kill and logout all users, type the following command:
# skill -KILL -v /dev/pts/*

Please note that send users warning message or logout notice using wall command to avoid data loss.

Other useful nifty utilities provided by procps package

• w : Show who is logged on and what they are doing
• kill : Send signal to a process aka kill process
• top : Display Linux tasks and other important stuff
• vmstat : Display virtual memory statistics
• free : Display free and used memory (RAM) statistics
• slabtop : Display kernel slab cache information in real time

source: HowTo