Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!zaphod.mps.ohio-state.edu!rpi!hogdenb
From: hogdenb@hope.its.rpi.edu (Brett M Hogden)
Newsgroups: comp.unix.aix
Subject: Re: X11R4 xterm problem
Message-ID: <8_N%}V%@rpi.edu>
Date: 28 Sep 90 18:30:51 GMT
References: <8632@ncar.ucar.edu>
Organization: Rensselaer Polytechnic Institute, Troy NY
Lines: 94
In-Reply-To: boote@bierstadt.scd.ucar.edu's message of 27 Sep 90 23:32:40 GMT

>>>>> On 27 Sep 90 23:32:40 GMT,
      boote@bierstadt.scd.ucar.edu (Jeff W. Boote) said:

     I ported X11R4 to the 6000 and I'm having a problem with xterm.
     Every once in a while I get the following error mesg:

     Warning: no access to tty; thus no job control in this shell...

     And true to the error mesage I have all kinds of problems with
     that shell.  It almost acts like I have two shells that keep
     swapping back and forth without any warning.  Has anyone else
     seen this message or have any idea what I can do to fix it?  Is
     this a system configuration problem/ an R4 problem or what?

     Also of concern: R4 xload gives me the following error:

     xload: cannot get name list from /unix

     I would be most appreciative of any and all help/comments/suggestions
     on these two problems.  Email unless you feel it would be of general
     interest.  I will summerize and post if there is interest.

Although I cannot offer much help, I can perhaps add some more
symptoms to the list.  I see the same results on AIX370 (on an IBM
3090-200S mainframe), AIX PS/2 v1.2, and AIX RS6000 v3.1:

First, in the supplied /bin/csh:

   3:hogdenb@aix01> ps x
        PID      TT STAT  TIME COMMAND
     111743      p4 R>    0:00 ps x
     111601      p4 S>    0:00 csh
   4:hogdenb@aix01>

Then, I start GNU bash [or tcsh, for that matter; both  yield similar
results]:

   4:hogdenb@aix01> bash
   ~
   1:aix01> ps x
        PID      TT STAT  TIME COMMAND
     111744      p4 S>    0:00 bash
     111749       ? R>    0:00 ps x       [note the TTY is unknown]
     111601      p4 S>    0:00 csh
   ~
   2:aix01> ps t
        PID      TT STAT  TIME COMMAND
     111744      p4 S>    0:00 bash
     111601      p4 S>    0:00 csh
   ~
   3:aix01> csh
   Warning: no access to tty; thus no job control in this shell...
   1:hogdenb@aix01> ps t
        PID      TT STAT  TIME COMMAND
     111744      p4 I>    0:00 bash
     111601      p4 I>    0:00 csh
   2:hogdenb@aix01> ps x
        PID      TT STAT  TIME COMMAND
     111744      p4 I>    0:00 bash
     111751       ? S>    0:00 csh
     111601      p4 I>    0:00 csh
     111760       ? R>    0:00 ps x
   3:hogdenb@aix01> echo $$
   111751
   4:hogdenb@aix01> exit
   ~
   4:aix01> exec csh
   1:hogdenb@aix01>

It seems, from all of this, that children of bash (and tcsh) do not
inherit knowledge of the TTY, and can't ever get access to it.
/bin/csh seems not to have this problem, but of course without source
code, I haven't been able to figure out _how_ it works.  As an aside,
some things that this problem breaks or otherwise shows up in are
/bin/passwd and screen.  passwd automatically fails, unless it is
called from an exec'd csh, or if it is exec'd itself.  screen just
yields the "Warning: no access..." message for each new window
invocation.

I'd _really_ like to hear from someone who has figured this one out. I
wish I had more time to play around with this problem.  It might in
fact be something trivial, that I am overlooking, or perhaps it is
some bizarrity of AIX that I just don't know about (yet!).  I
apologise for the length of this follow-up, but I thought that some
extra information might be useful.

Some 85+ lines back, I cited that Jeff said he would post a summary of
responses.  I hope this helps someone out there provide him with a
useful summary to share. :-)

Brett

-- 
      *  Brett M Hogden -- hogdenb@rpi.edu -- hogdenb@rpitsmts.bitnet  *