m5@lynx.UUCP (Mike McNally) (07/14/88)
I am running 4.2BSD on an Integrated Solutions Optimum (hah!) V system.
I'm having the damdest problem involving (I think) the Bourne shell.
Here's the scene. I have a "more" replacement program that seems to
work just fine and dandy all the time, in all cases, *EXCEPT* when it's
used at the tail end of a pipe in sh when more than two processes are in
the pipe:
pg balloon # works fine
ls | pg # works fine
ls | cat | pg # surprise!
The failure involves the terminal sg_flags getting screwed up. The only
possible culprit (so far as I can tell) is the shell. The following
pipeline, for example, works fine:
ls | cat | (sleep 5; pg)
The shell attacks, but pecause in this case pg doesn't actually get going
for a while, it is the last thing to mess with the sgttyb. Without the
sleep, pg starts up but midway through painting the first screen, the
terminal flags are *changed* and of course it's downhill from there.
Remember, pg works just fine from csh and my own shell.
Is this one of those old bugs that everybody chuckles about at USENIXes,
like the (uncountable) bugs in vi? Is it a secret feature that I really
want because of some obscure reason?
--
Mike McNally of Lynx Real-Time Systems
uucp: lynx!m5 (maybe pyramid!voder!lynx!m5 if lynx is unknown)