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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 (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


The procps package contains 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. Procps includes ps, free, skill, pkill, pgrep, snice, tload, top, uptime, vmstat, w, watch and pdwx commands.

Task: How To Halt/Stop a User Called vivek

Open a command-line terminal (select Applications > Accessories > Terminal), and then type the following commands. First, switch to the root user by typing su - and entering the root password, when prompted (you can also use sudo if configured). Type the skill command as follows:
# skill -STOP -u vivek
The skill command sends a terminate command (or another specified signal) to a specified set of processes.

Task: Resume Halted User Called vivek

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

Task: Kill and Logout a User Called vivek

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

Task: Kill and Logout All Users

The ultimate command to kill and logout all users is as follows:
# skill -KILL -v /dev/pts/*

WARNING! These tools are obsolete, unportable and it is here due to historical reasons. Consider using the killall, pkill, and pgrep commands instead as follows.

pkill command

To halt or stop a user called vivek, enter:
# pkill -STOP -u vivek
To resume a user called vivek, enter:
# pkill -CONT -u vivek
To kill all php-cgi process owned by vivek user, enter:
# pkill -KILL -u vivek php-cgi

Other useful nifty utilities provided by procps package

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

  • max August 15, 2006, 8:48 am

    This stuff is very cool!
    I manage an iternet cafe linux-based and to log-out users remotely since now I first logged in the client machine via ssh and then export DISPLAY=:0 and kdeinit_shutdown.But doing that I was lucky with kde as default wm, while ‘skill -KILL -u user’ is a better one_line command solution and for (I guess) all windows managers.
    What I’m still wondering is: how to login remotely a user assuming that the default login manager is kdm?
    Thanks in advance for any hint.

  • nixCraft August 15, 2006, 9:39 am

    Hey max,

    Great to know you are using Linux for your internet cafe.

    skill should works with an wm or shell as it directly sends a signal to user.

    >What I\’m still wondering is: how to login remotely a user assuming that the default login manager is kdm?

    Sorry but I am not getting your question. Can you explain it little more?

    • Ammar Shaikh January 11, 2012, 7:56 am

      Hello;

      I m also not getting your question so please explain it briefly or understandable that is very helpful to you and all also…

  • max August 15, 2006, 12:01 pm

    >Sorry but I am not getting your question. Can you explain it little more?
    Well, when a customer finish his session is comfortable for me remotely close the session, but when I need to start a new one I need to sit-up from my chair and then go to the client and put the passwd (the user account is setted as default in kdm config) manually in the kdm welcome_login_window.
    Now I’m just wondering how to put remotely the passwd in kdm to open the session again without (being lazy :-]) uprise from my chair?
    I hope this wouldn’t be a too much tricky question an sorry about my english that isn’t my first language @^_^@

  • nixCraft August 15, 2006, 7:03 pm

    Now, I understand your problem, you do not want go to each PC everytime new customer arrives. You can kill your customers session with skill but now you want to do auto login right from your own admin PC

    Well I do not have exact solution but you can use KDE auto login facility to login the user automatically…

    On the other hand, you may be writing some script, which will log them automatically

    Another solution is kill user using skill
    When new person comes for browsing just tell him to seat in front of computer
    You login from your own admin pc to remote linux desktop system over ssh
    And you type the command startx&
    It will start the session on remove computer
    In order to work this all system must boot to text mode
    SSH should be running on all system
    And autologin must be turned on for all linux system

    Hope this helps

  • deivs January 22, 2007, 10:30 am

    how to logout specified user after one hour automatically,how to do ?

  • nixCraft January 22, 2007, 3:11 pm

    deivs.

    You need to write a script. There is no inbuilt facility available, AFAK

  • Paul May 15, 2007, 7:54 pm

    Hi,

    I was pleased to see the skill inf have ld sessins n an LTSP server. I have since set a timeout uing TMOUT=7200 in /etc/profile.
    Iuse skill -KILL -u paul to try and remove the old sessions. It succesfully removed one but doesn’t seem to remove the other 2 that are reported by ‘who’. Is it possible that ‘who’ is reprting stale/non-existant sessions?

  • nixCraft May 16, 2007, 9:46 am

    Try to use pkill command
    pkill -KILL -u username

  • Masood Yarmohammadi May 27, 2007, 3:39 pm

    Hello,
    i use
    skill -KILL -u didi root

    Now, i can’t login to ssh!

    • Waqar June 13, 2011, 6:52 am

      That’s Because u also killed “SSH”, u need to login via console and restart SSH Services.

  • Hong@macau July 18, 2007, 9:34 am

    i think when i enter this command
    skill -KILL -u root

    this will be kill all the process that create by root. such as ssh telnet process.

  • deivs September 16, 2007, 9:38 am

    script to logout the users in the specific time

  • De.. December 7, 2007, 9:09 pm

    i want to delete the process because my systems average load is too high 150.0 and more some time
    and when i delete them ..they goes to and start increasing the load continously..
    the process are perl scripts..
    please help urgent

  • De.. December 7, 2007, 9:11 pm

    the process hang up and when i shen them it shows like “defunction”

  • Terry January 8, 2008, 9:05 pm

    Oops didn’t read through all the threads. I had a user who was logged on remotely as root but when I ran the command we were kicked out of our SSH sessions
    Is there any way to recover SSH functionality short of rebooting

  • Anonymous September 5, 2008, 4:00 am

    Only if you have another way of logging in (e.g. telnet, vnc, etc)

  • Afrizal October 11, 2008, 4:16 pm

    Thank you for your shared knowledge.

    Great info.

    thanks,

    zall

  • lee o November 9, 2008, 6:01 pm

    Something for Linux Monty Python fans – one of you show a more funny way of kicking users off a linux box than THIS ONE HERE.. Very entertaining!

  • viper December 6, 2008, 7:46 am

    how about to remove halt application..
    at the bios I can’t find to solve that..
    thanx…

  • kaminisuresh February 26, 2010, 11:05 am

    hi
    this is suresh i want which pc is having some server,how to identify which is having server

  • bishnoink September 15, 2010, 5:01 am

    I have tried “skill -KILL /dev/pts/*” its not working on rhel5.

    alternative to kill all users sessions except “root” is:

    who -w|awk ‘{print $1}’|grep -v root|xargs skill -KILL -u
    *don’t forget to use “grep -v root” otherwise this will kill all the processes.

    Thanks

  • Bilal Bhat November 28, 2010, 7:27 am

    Brilliant bishnoink, you made my life easy… Thanks for sharing the command…

  • Mish March 9, 2011, 1:12 pm

    I wanna know, how to block the users being ruining programs in bios level.
    this is like blocking websites for various users in bios level.

    ex; user “A” logging and browse internet (www.google.com)
    after user “B” logging and browse the internet BUT HE CANT GO TO “www.google.com” from any browser.

    If you all have a suggestions how to block this kind of a session, I would be much appreciated.

    Tx

  • Vishnu Ram May 26, 2011, 9:04 am

    Hello,

    I need to kill an user session which is not being used by that particular user for last 10 days. Please help me to get a script for that.

  • Naresh Kumar May 26, 2011, 12:19 pm

    @ Vishnu,

    You can use following command.
    who -w|awk ‘{print $1}’|grep username|xargs skill -KILL -u

  • Mehdi September 8, 2011, 2:22 pm

    Hi,

    If all the sessions have been made by a user, i.e. vivek, is it possible to kill a session based on TTY?

  • Daniel Vieceli March 13, 2012, 2:06 am

    Thanks, very good.

  • PVIBES March 7, 2013, 8:37 pm

    I found this guys.
    Just replace USERNAME with the desired user session to be killed.

    kill -1 `ps ax | grep -i USERNAME | grep -i priv | cut -d ” ” -f 1`

  • cilgin_dj_hore April 28, 2014, 4:01 pm

    aq ibneleri hey dude this fucking code skill -STOP -u root fucked my machine . i di o T

  • chika August 29, 2014, 7:34 am

    pkill -9 -u ardi