[ILUG] Piping to multiple processes (which might die)?

[Brian Foster]

  | Date: Wed, 31 Jul 2002 15:13:23 +0100
  | From: Ronan Cunniffe <ronan at cunniffe.net>
  | 
  | Um, my test was to tee to a fifo I didn't read from... resulting
  | in the other reader hanging around forever.... not realising that
  | never-opened-for-reading and opened-and-later-closed might be
  | different.

 ah!  yes!  this is one of those gotchas everyone stumbles
 over.  the writer of a never-opened-for-reading pipe will
 quickly block (as soon as the pipe's limited buffer fills
 up).  but the writer of opened-and-later-closed pipe gets
 an EPIPE error (and the usually-terminal SIGPIPE signal).

 the typical stumble is someone creates an anonymous pipe
 with pipe(2), but forgets to close(2) the reader's fd in
 the writer-process (or visa-versa) .... and then wonders
 why the real reader never sees an EOF and/or the writer
 is never gets an EPIPE/SIGPIPE.  various FAQs and many
 books probably discuss this topic in depth to the death.

  |             Sensible behaviour has now been observed.

 good!  and good luck.
cheers,
	-blf-
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