uptime, w, and who show nobody logged in

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Nov 022000
 

uptime, w, and who show nobody logged in

I was working on a box for a client.  They asked me to help.   After fixing the problem, I checked to see if the client was still logged in.   Here’s what I saw:
[root@p100:/var/log] # who
[root@p100:/var/log] # w
9:21PM  up  5:18, 0 users, load averages: 0.08, 0.09, 0.03
 USER             TTY      FROM              LOGIN@  IDLE WHAT

That’s wrong.  You can’t issue a who or a w and get no users.  You’re logged in.   You should at least see you.  uptime gave similar incorrect information.

Actually, you can be logged in and not seen.  Here are the various things people have mentioned:

  • screen will let you do this, using the deflogin off option in your screen rc.  add a chmod 711 ~; touch .nofinger and you’re pratically invisible

My first thought was: someone has root’d this box.

So I asked on IRC and was told that it seems that my /var/log/wtmp is screwed.  DOH!

So I logged out and back in again.  Then everything worked:

[root@p100:/var/mail] # who
dan              ttyp1   Nov  1 21:24   (203.79.82.27)
[root@p100:/var/mail] # uptime
 9:50PM  up  5:47, 1 user, load averages: 0.00, 0.01, 0.00

Why?

The explanation is easy.  The problem I was fixing was a full /var filesystem.  That meant the contents of /var/log/wtmp was incorrect.   It’s updated each time someone logs in.  By logging out and back in again, that file was updated correctly.

  5 Responses to “uptime, w, and who show nobody logged in”

  1. doni andri says:
    January 1, 2002 at 12:57 pm

    i’ve read the article ‘uptime, w, and who show nobody logged in’
    then i try to find something like "screen" as stated on it :

    screen will let you do this, using the deflogin off option in your screen rc.
    ^^^^^^^^^

    So, can you explain me where exactly i must use screen rc? Is it like rc.screen or screen.rc or else? since i can’t finde rc like that. And second, the option "deflogin", how can i write it in my screen rc?

    thanks for your answer

    please reply to:doni@ee.itb.ac.id

    – doni ac –

    • Dan Langille says:
      January 1, 2002 at 8:12 pm

      screen as in /usr/ports.

      cd /usr/ports
      make search name=screen

      I’ve also updated the article to include a link to the <A HREF="/screen.php">screen article</A>.

  2. Jeff Parker says:
    January 3, 2002 at 1:32 am

    What is the maximum number for loadaverage in uptime? I am trying to script a simple utilization and I need to know that max
    Thanks in advance.
    Jeff