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From: libes@cme.nist.gov (Don Libes)
Newsgroups: comp.unix.questions
Subject: Re: A Pipe Question
Message-ID: <3577@muffin.cme.nist.gov>
Date: 30 May 91 14:52:10 GMT
References: <1991May24.025917.18874@csc.canberra.edu.au> <16262@smoke.brl.mil> <1991May30.093934.27121@thunder.mcrcim.mcgill.edu>
Organization: National Institute of Standards and Technology
Lines: 20

In article <1991May30.093934.27121@thunder.mcrcim.mcgill.edu> mouse@thunder.mcrcim.mcgill.edu (der Mouse) writes:
>[Sun 4.x has broken ptys - if slave side is closed, buffered data is
>thrown away after some delay ...  (This causes problems with our local
>emacs variant; when it's suspended with a compile going, compile output
>lost if it isn't resumed "soon enough" after the compile finishes.)]

Sun, AT&T, and others know about this.  (I know, I called a few.)  I
never did get what I felt to be a satisfactory answer.  The most
plausible suggestion was that this is a "feature" to lessen the
likelihood of inadvertently opening a new slave while an old master is
still active.  (Hard to believe, isn't it?)  Fixing this flaw requires
fixing the usual pty kludges related to protection and allocation.

>[%] The delay is more than about fifteen seconds but less than a few
>    minutes.  I haven't bothered to pin it down more precisely.

On Suns the interval is indeed 15 seconds.  Even worse is the Cray
which throws away unread data IMMEDIATELY upon slave close.

Don Libes          libes@cme.nist.gov      ...!uunet!cme-durer!libes