Path: utzoo!utgpu!water!watmath!onfcanim!dave
From: dave@onfcanim.UUCP (Dave Martindale)
Newsgroups: news.admin
Subject: Arbitron "Users" count is very wrong under BSD
Message-ID: <15538@onfcanim.UUCP>
Date: 18 Jan 88 15:06:54 GMT
Reply-To: dave@onfcanim.UUCP (Dave Martindale)
Organization: National Film Board / Office national du film, Montreal
Lines: 36

This morning, arbitron ran automatically and its output was mailed to me.
I was very surprised to find that we have 27 active users on this machine.

On BSD unix, arbitron generally uses the pipeline

  nusers=`last | sort -u +0 -1 | wc -l`

to count the number of users who have logged in this month, in order to
ignore dormant users in the passwd file.  Running the "last | sort"
component of the pipeline by hand did indeed produce 27 lines of output,
which consisted of:

  13 living, breating users
  10 uucp logins
   2 dummy entries "reboot" and "shutdown"
   2 lines due to the printf("\nwtmp begins %s\n", ctime(whatever))
     that last does after printing all data in the file

So, 13 out of 27 reported users were real.  I expect figures to be similarly
inflated on most BSD systems.

I've replaced the pipeline above with:

  nusers=`last | sed -e '/^$/d' -e '/^wtmp begins/d' -e '/ ~ /d' -e '/^U/d' \
	| sort -u +0 -1 | wc -l`

Since it depends on the fact that our uucp logins all begin with 'U', you
would have to edit it as appropriate for your username conventions.

The pipeline used for USG systems probably needs patching in a similar manner.

If everyone fixed this, I wonder how much the "total users" count
would go down net-wide?

	Dave Martindale
	{musocs,watmath}!onfcanim!dave