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Date: Wed, 14 Sep 2005 16:36:54 -0500
From: Noel Jones <noeldude@gmail.com>
To: freebsd-questions@freebsd.org
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References: <20050914190721.67892.qmail@web52604.mail.yahoo.com>
Subject: Re: script advice
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On 9/14/05, John Williams <jbiddlew@yahoo.com> wrote:
> Dear List,
> I have a requirement for a maximum of one user logged in at any given tim=
e.  Following is a .profile script I wrote to enforce the requirement.  The=
 problem is that when the script runs, sometimes the user trying to login i=
s identified as logged in and sometimes he/she is not identified as logged =
in.  I.e., there is a race condition between script execution and login com=
pletion.  Any advice for how to make it work properly?  The brute force way=
 is to loop on waiting for the user to be logged in, as identified by the w=
ho command, and then check the time of the login so as not to be confused i=
f the user is already logged in.  Is there a better way?  Thanks!
>=20

Exclude the users own tty.

TTYDEV=3D`/usr/bin/tty`
TTY=3D`/usr/bin/basename $TTYDEV`
USERS=3D`/usr/bin/who | /usr/bin/grep -v "$TTY"`

[ -z "$USERS" ]  && {
   echo Other users logged on!
   echo $USERS
   echo logging out...
   logout
}


--=20
Noel Jones