Re: who and utmp

[Andreas Jaeger <aj@arthur.rhein-neckar.de>]

>>>>> Dale Harris writes:

 > Ok, turns out that they are coming out with a new version of sh-utils and
 > it seems to pretty much work except that there may be a possible bug in 
 > glibc, it doesn't seem to remove old entries from utmp, notice:

 > rodmur   tty1     Aug 14 16:22
 > rodmur   ttyp0    Aug 14 16:22
 > rodmur   ttyp1    Aug 15 09:47
 > rodmur   ttyp2    Aug 14 16:25
That would be a problem with xterm/login etc not calling the correct
cleanup functions.

 > I'm logged into the ttyp2 at this time, w from procps-2.02 appears to handle
 > this correctly though:

 >  12:35pm  up 4 days, 22:01,  4 users,  load average: 0.00, 0.01, 0.00
 > USER     TTY      FROM              LOGIN@   IDLE   JCPU   PCPU  WHAT
 > rodmur   tty1     -                Sat 4pm 20:12m 12.43s  0.01s  startx         
 > rodmur   ttyp0    :0.0             Sat 4pm  0.00s  0.94s  0.31s  mutt 
 > rodmur   ttyp1    :0.0              9:47am  2:36m  0.26s  0.26s  -bash 


 > So it could be a bug in who or glibc.  

 > Another thing that surprises me is the way utmp is accessed:

 > access("/var/run/utmpd.rw", F_OK)       = 0
 > socket(PF_UNIX, SOCK_STREAM, 0)         = 3
 > connect(3, {sun_family=AF_UNIX, sun_path="/var/run/utmpd.rw"}, 110) = -1 ECONNRE
 > FUSED (Connection refused)
 > close(3)                                = 0
 > socket(PF_UNIX, SOCK_STREAM, 0)         = 3
 > connect(3, {sun_family=AF_UNIX, sun_path="/var/run/utmpd.ro"}, 110) = 0

 > That is from a trace of who (from sh-utils 1.16m), it doesn't have any 
 > invocation of connect or any other socket types call in the source, it 
 > in fact tries doing a open on /var/run/utmp.  So I'm guessing that glibc
 > or utmpd somehow catches the open to /var/run/utmp and then directs it to 
 > the /var/run/utmpd.* files?  Why?

That's the result from calling getutent.  Read the glibc doku about utmpd.

Andreas
-- 
 Andreas Jaeger   aj@arthur.rhein-neckar.de    jaeger@informatik.uni-kl.de
  for pgp-key finger ajaeger@aixd1.rhrk.uni-kl.de