defunct/inactive telnet sessions

tpmadigan · 01-30-2008, 10:24 AM

Fellow Linux Admins:

I am experiencing a problem with the "who -u" command in that it is displaying sessions that are no longer signed on to the server. Consider the following output from the "who -u" command:

gooduser pts/1 Jan 30 08:00 . 3173 (192.168.1.106)
intv1407 pts/62 Jan 29 18:45 ? 17430 (DTCLV01.somecompany.com)
intv1207 pts/29 Jan 29 17:29 ? 11714 (DTCLV01.somecompany.com)
intv1208 pts/49 Jan 29 17:32 ? 12459 (DTCLV01.somecompany.com)
intv1215 pts/75 Jan 29 17:35 ? 13766 (DTCLV01.somecompany.com)
intv1415 pts/14 Jan 29 19:32 ? 19155 (DTCREAD.somecompany.com)

With the exception of "gooduser", none of the other users that are displayed are actually logged in. If I perform a "ps -fp" on any of the processes listed in the 4th column (except for 3173), no details are shown. If I attempt to "kill -9" any of those processes, I receive output similar to:

[tom@cascadia ~]$ kill -9 17430
bash: kill: (17430) - No such process
[tom@cascadia ~]$

How can I remove those "dead" processes from the listing preferably without rebooting the server? This is a "24 x 7" never-shut-down servers that should not be rebooted unless the end of the world is near! Please note that this server is running Red Hat Enterprise 4 AS.

Many thanks in advance for your help!

carltm · 02-03-2008, 09:02 AM

Those are zombie processes. The telnet session has died, but there
are still processes running in subshells. In other words, someone
started a process while logged in through telnet and ended their session
without killing all their processes first. If you find and kill the
other processes, the zombie telnet sessions will disappear.

tpmadigan · 02-04-2008, 08:56 AM

As luck would have it, the sessions disappeared all on their own, so the subprocesses owned by those sessions must have terminated or been killed somehow. I'll keep a note of your suggestions for the next occurrence of this problem. Many, many thanks for your help. Happy Linux-ing!!