cannot start cmdtool on NCD X-terminal under SunOS 4.1

[Andrew Rutherford]

In article <2922 at brchh104.bnr.ca> sitongia at hao.ucar.edu (Leonard Sitongia) writes:
>I've been using an NCD X-19 terminal with xdm from MIT X11R4 displaying a
>cmdtool from OpenWindows 2.0 served from a Sun-4/280 running SunOS 4.0.3 for 
>some time.  It is simply exec'd from the .openwin-menu.

[ ... Some stuff deleted ... ]

>The failing cmdtool appears normal, in that it opens ok, and echos input,
>but will not execute input.
>
>In any case, when the cmdtool is started up, the xdm-errors reports:
>
>ttysw-TIOCSPGRP: Interrupted system call

I think we need this stuck in an FAQ. It's the kind of problem that people
  ask in newsgroups they don't often have time to read :-(

Anyway, the answer to your question is to invoke the cmdtool as

  setsid cmdtool <<options>>

The reason for this is that cmdtool does some funny stuff with process
  groups, and falls in a heap if it's not invoked from a terminal. Usually,
  this is OK as the process can trace it's ancestry back to a login session
  on the console. Xdm, however, divests itself of controlling terminals,
  and cmdtool fails.

There are three ways around this:
  - Start cmdtool up from another login (as you've discovered)
  - Start cmdtool up as "setsid cmdtool"
  - Use xterm.

Personally, I prefer the latter, as then I can use my cursor keys in tcsh
  and have scroll bars at the same time.

Hope this helps,
		Andrew.
--
Andrew Rutherford                        andrewr at ucs.adelaide.edu.au
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