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From: Greg Wooledge <wooledg@eeg.ccf.org>
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Subject: Re: Proposed new feature for bash:  unbuffered pipes, part 1: overview
Date: Wed, 22 Apr 2020 07:36:06 -0400
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On Tue, Apr 21, 2020 at 08:38:41PM -0400, Dale R. Worley wrote:
> The "unbuffered pipe" symbol ">|>" causes Bash to set in the
> environment of the "grep" process a variable "STDOUT_UNBUFFERED" with
> a value that contains the dev and ino values for the pipe which the
> "grep" process sees as fd 1.

Which libc implements this?

> References
> 
> 14 Sep 1999
> https://marc.info/?l=glibc-bug&m=98313957306295&w=4
> "[REMINDER] stdio buffer flushing control environment variable"

The next message in the thread is from Ulrich Drepper, saying:

  I will not implement this since it's completely up to the application
  to do this.  One knows in advance when this is necessary.  If there is
  a problem with the current code to select when line-buffering is used
  (we use as everybody else isatty) then one can talk about this.  I
  think it is correct, though.