Friday, December 3, 2010

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 ;)
There is a package called procps. It includes various useful (read as nifty) utilities. One of such utility is skill which is responsible to send a signal to users and process such as:
  • Halt user terminal
  • Kill user and logout
Also note that these are utilities to browse the /proc filesystem, which is not a real file system but a way for the kernel to provide information about the status of entries in its process table.

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

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