How to kill a logged in user?

Nifty Hat Mitch mitch48 at
Wed Nov 10 08:01:25 UTC 2004

On Tue, Nov 09, 2004 at 11:33:56AM -0300, Alexandre Cavalcante Alencar wrote:
> From: Alexandre Cavalcante Alencar <alexandre.alencar at>
> To: For users of Fedora Core releases <fedora-list at>
> Organization: Aspec S/C Ltda
> Date: Tue, 09 Nov 2004 11:33:56 -0300
> Subject: Re: How to kill a logged in user?
> Reply-To: alexandre.alencar at,
>         For users of Fedora Core releases <fedora-list at>
> Hi,
> Ti kill completelly the user, use the skill command, take care using it,
> read it's man page.
> skill <user>
> skill -9 <user>

Old unix wisdom....

When killing any process/ user start out lightly.

Use the -HUP signal first.

The signal HUP (hangup) is the signal sent when a modem line
disconnects.  In olden days this was common and most well coded tools
do the right thing.  There is a reason HUP is signal #1.

Since modem line disconnects were so common most programs trap the
"-HUP" signal and tidy things up then exit.

       The default signal for skill is TERM. Use -l or -L to list
       available signals.  Particularly useful signals include HUP,
       INT, KILL, STOP, CONT, and 0.

TERM is a good second choice....

Since Kill -9 cannot be caught by the process, the process cannot
signal child processes (one source of zombies), write data to and
close files (sync buffers), notify clients, remove lock files, unlink
temp files, and other good programming practices and actions. SigKILL
should be used LAST and with enough time after lesser signals for
normal system calls to finish and for the process to tidy up.

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