Understanding the "who" command

[Net Llama!]

According to the who man page, it obtains its output from /var/run/utmp
or /var/log/wtmp.

w obtains its information from /var/run/utmp exclusively.

So if you're getting different information from the two commands, I'd 
guess that who is using /var/log/wtmp.

On Fri, 4 Aug 2006, Brad De Vries wrote:

> Hey all, I'm hoping that someone can give me a little insight into
> where the data comes from for the "who" command.  Here's what I'm
> seeing on my box right now:
>
> ---------
> /home/bjd> who
> bjd      pts/0        Aug  4 13:55 (qad-gr)
> bjd      pts/2        May 30 15:53
> /home/bjd> ps -ft pts/2
> ps: error: TTY could not be found.
> usage: ps -[Unix98 options]
>       ps [BSD-style options]
>       ps --[GNU-style long options]
>       ps --help for a command summary
> /home/bjd> ps -ef | grep bjd
> bjd       1729  1727  0 13:55 ?        00:00:00 /usr/sbin/sshd
> bjd       1731  1729  0 13:55 pts/0    00:00:00 -bash
> bjd       1774  1731  0 13:56 pts/0    00:00:00 ps -ef
> bjd       1775  1731  0 13:56 pts/0    00:00:00 grep bjd
> /home/bjd> w
> 14:07:54  up 332 days,  3:45,  2 users,  load average: 0.01, 0.02, 0.00
> USER     TTY      FROM              LOGIN@   IDLE   JCPU   PCPU  WHAT
> bjd      pts/0    qad-gr            1:55pm  0.00s  0.07s  0.01s  w
> ---------
>
> You can clearly see that the "who" command shows two users but the
> "ps" and "w" commands only shows processes attached to one.
>
> I could reboot the server but I'm hoping to achieve a full year of uptime.
>
> Thanks,
> Brad.
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>

-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Lonni J Friedman                        netllama at linux-sxs.org
LlamaLand				http://netllama.linux-sxs.org