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Re: problem with who


From: Bob Proulx
Subject: Re: problem with who
Date: Sat, 9 Feb 2002 13:07:16 -0700

> I use debian woody with kernel 2.4.17, gnome and gnome-terminal.
> 
> who doesn't report anything, as nobody was logged in.
> I use --login option of gnome-terminal but nothing.
> Even if I use "su -" it doesn't report nothing.
> 
> the files utmp and wtmp have the following permissions
> 
> -rw-rw-r--    1 root     utmp         5376 Feb  5 16:02 /var/run/utmp
> -rw-rw-r--    1 root     utmp        77568 Feb  5 15:45 /var/log/wtmp
> 
> any suggestion?

Check the permissions on your terminal program.  On hpux these need to
be suid-root so that they can write to the utmp files.  If the suid is
removed then utmp is not updated and who can't show anything.

  ll /usr/bin/xterm
  -rwsr-xr-x    1 root     root       489923 Sep 26 14:43 /usr/bin/xterm

HOWEVER, I do not know how other systems operate with respect to this.
Recently there has been a movement to change the behavior so that
these programs do not need to be suid-root to improve security.
Debian may be one of those with new semantics and so this may be
nothing more than a red-herring for you.  But it is something to
check.

AFAIK and off of the top of my head when the terminal allocates a pty
it writes information to the utmp entry.  If it can't do that then you
never see anyone logged in with who which is doing nothing more than
dumping the contents of the utmp file.

The --login options do not have any effect on utmp logging.  What they
do is to tell the shell (by exec(2)ing them with a "-" as in "-sh")
that they should perform login startup sequences such as reading the
/etc/profile, $HOME/.profile, etc.

Bob



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