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Date: Fri, 24 Apr 1998 13:14:00 -0700
From: Gregg Townsend <gmt>
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To: [e-mail], icon-group
Subject: Re:  Using icon pipe features
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Most Unix utilities will buffer their output if it's connected to a pipe.
That means that even if you were able to open a two-way pipe to something
like "sed", you wouldn't be able to just write it a line and then read
the filtered result.  You'd need to write enough lines to make sed flush
its buffer before you'd be able to read anything back.  This, of course,
gets somewhat tricky, because sed can block if too much accumulates in
its output pipe.  The tough part is that the buffering is going on
inside the forked process where you can't generally control it.

I've speculated that it might be possible to make something work using
pseudo-terminals (pttys), but I haven't tried it.

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   Gregg Townsend              Gould-Simpson Building   [e-mail]
   Staff Scientist             1040 E. 4th St.          32 13 45N  110 57 16W
   Dept. of Computer Science   PO Box 210077            tel: [phone]
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