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Date: Mon, 5 Nov 2001 19:20:52 -0600 (CST)
From: Chris Abbey <linux@cabbey.net>
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To: Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: How can I know the number of current users in the system?
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Today, Riley Williams wrote:
> Here's a simple shell command to provide that information:
>
> 	who | wc -l
>
> Try it and see...

Actually that's not a fair count of the number of users on the box,
only the number that are *logged in*. On one of our boxes at work,
that would miss about 80% of the users, maybe more. Anyone that
RSH's or SSH's in without a tty wouldn't be counted:

cabbey@CHESIRE ~> ssh -T tweedle who
cabbey@CHESIRE ~>

so even though I was executing who on tweedle it didn't see me
logged in. A more realistic situation:

[cabbey@tweedle cabbey]$ who
cabbey   pts/0    Nov  5 19:05
cabbey   pts/1    Nov  5 19:05
[cabbey@tweedle cabbey]$

pts/0 is my pine session, pts/1 is the shell I executed who in,
there are also two copies of "xeyes" running back to chesire
that were started as 'ssh -T tweedle /usr/X11r6/bin/xeyes -display
chesire:0' but don't appear in who

going back to running it remotely:

cabbey@CHESIRE ~> ssh -T tweedle who
cabbey   pts/0    Nov  5 19:05
cabbey   pts/1    Nov  5 19:05
cabbey@CHESIRE ~>

If those were move cpu hungry programs than xeyes,
like vncserver with a complete kde/gnome desktop
running under it then you could really be missing
some data from a scheduling pov... which as I recall
was what the original poster wanted to fiddle with.

-- 
now the forces of openness have a powerful and
  unexpected new ally - http://ibm.com/linux


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