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I am a newbie to Linux commands and was trying to delete a user on a CentOS 6 via an SSH connection on Putty, it was giving an error like "userdel: user is currently logged in", hence, i searched for a possible solution of this problem.

Googling on the above error i found a link Unable to remove user: "user is currently logged in" When i tried the solution given on this page and executed the "kill -9 -1" command after executed the "su - username" command the putty session was automatically closed and everything on that server just stopped working.

Any suggestions or any link which can help us out will be grateful to have as we are in a big danger because this is our main production server.

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user1321244
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    Congratulations, you killed init. Someone's going to have to powercycle that machine. – Shadur Jun 09 '15 at 05:03
  • @Shadur `kill -9 -1` doesn't kill init. It's the only process for which the kernel implements such protection. So in principle the system can be configured such that after `kill -9 -1` init will start the bare minimum of services again. If such configuration has not been done in advance, one shouldn't run `kill -9 -1` as root (it is rarely a good idea anyway even if you have). – kasperd Jun 09 '15 at 05:56
  • kill -9 -1 kills all user process excluding init. – c4f4t0r Jun 09 '15 at 06:00

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You shot yourself in the foot.

The only way that server is going to come back up is if someone powercycles it. Once it's back on, try to delete the user again.

The next time you get an error like this trying to delete a user, try to manually kill processes which owned by the user you want to delete (ps aux|grep <username> or `pkill -u ) and try again.

Shadur
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Maxiko
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  • Thanks a lot you saved me. And thank god Digital Ocean have a console access via their dashboard to which we can reboot a system. @Shadur thanks for your immediate response as you got me the idea of rebooting the system. – user1321244 Jun 09 '15 at 05:19
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    After analyzing the "/etc/passwd" if found an entry of the user which i want to delete as follows `user1:x:0:0::/home/user1:/bin/bash` which i think has privileges as a root user and therefore, deleting that user even after executing `su - user1` command caused the pid "1" to be killed for the root user as well. Please correct me if m going in a wrong direction. – user1321244 Jun 09 '15 at 06:43
  • @user1321244 Looks like somebody messed things up pretty badly when creating that user. – kasperd Jun 09 '15 at 06:47
  • The "good" (relatively speaking) news is that you can just delete that user's entries from `/etc/passwd` and `/etc/shadow` and clear its home directory and you'll be set... But I recommend taking a blunt object when you discuss this particular security feature with the admin that set that system up. – Shadur Jun 09 '15 at 18:21