Mail Archives: cygwin/2001/01/19/04:43:57
On Thu, Jan 18, 2001 at 01:49:01PM -0700, Kevin Wright wrote:
> Hello,
>
> I recently upgraded to Cygwin 1.1.7 (from 1.1.4) and am happy that
> the shellutils who utility now reports the current users logged in.
> It might have been working for a long time but I personally just got
> it working now.
>
> Here's the current output of who:
>
> $ who
> kwright tty0 Jan 17 19:00 (holstein-mobile.ASPECTDV.COM)
> kwright tty1 Jan 17 17:53 (holstein-mobile.ASPECTDV.COM)
> kwright tty2 Jan 17 18:31 (holstein-mobile.ASPECTDV.COM)
>
> According to the output from strace, who derives it's info from
> /var/run/utmp. However, if someone logs in remotely via telnet,
> /var/log/wtmp gets updated. To find out who is logged in remotely,
> I have to pass /var/log/wtmp as a parameter to who, thus:
>
>
> $ who /var/log/wtmp
> [output deleted]
> kwright tty2 Jan 17 16:54 (holstein-kw)
> kwright tty3 Jan 17 17:22 (holstein-mobile.ASPECTDV.COM)
> kwright tty1 Jan 17 17:53 (holstein-mobile.ASPECTDV.COM)
> kwright tty2 Jan 17 18:31 (holstein-mobile.ASPECTDV.COM)
> kwright tty0 Jan 17 19:00 (holstein-mobile.ASPECTDV.COM)
>
> This not only gives you the list of current users but also a
> list of past logins, which means I can't tell if the who
> is still logged in. (other than checking the current number
> of in.telnetd processes)
>
> My question is, is this expected behavior or should telnetd also
> be writing to /var/run/utmp? I looked at the source and found
> references to utmp but they are ifdeffed and I couldn't figure
> out whether it is supposed to be used or not.
I just tried to remotely logon to my Cygwin box using ssh, telnet
and rlogin. As far as I can tell, everything is ok. Login with all
three methods leave their marks as they should. I can't see any
flaw that a login via telnet doesn't show up in the standard
`who' output.
Just to be sure, I had another look into the man page of utmp/wtmp
on my Linux box. Excerpt:
The utmp file allows one to discover information about who
is currently using the system. There may be more users
currently using the system, because not all programs use
utmp logging.
Especially the latest sentence is of interest. While telnet is
doing the right thing AFAICS, I think the above is good to know.
The wtmp file records all logins and logouts. Its format
is exactly like utmp except that a null user name indi
cates a logout on the associated terminal.
So wtmp is containing the right entries either as your above
output states.
[...] wtmp is maintained by
login(1), and init(1) and some versions of getty(1). Nei
ther of these programs creates the file, so if it is
removed record-keeping is turned off.
That's just FYI. Keep track of the size of wtmp when you are using
it since it always grows unless you don't shrink it to size 0
from time to time.
Corinna
--
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Developer mailto:cygwin AT cygwin DOT com
Red Hat, Inc.
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