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diff --git a/doc/gawktexi.in b/doc/gawktexi.in index ec715346..8d721c29 100644 --- a/doc/gawktexi.in +++ b/doc/gawktexi.in @@ -26568,10 +26568,27 @@ print @dots{} |& command # start two-way pipe @end example @noindent -Using ptys usually avoids the buffer deadlock issues described earlier, at some -loss in performance. If your system does not have ptys, or if all the -system's ptys are in use, @command{gawk} automatically falls back to -using regular pipes. +If your system does not have ptys, or if all the system's ptys are in use, +@command{gawk} automatically falls back to using regular pipes. + +Using ptys usually avoids the buffer deadlock issues described earlier, +at some loss in performance. This is because the tty driver buffers +and sends data line-by-line. On systems with the @command{stdbuf} +(part of the @uref{http://www.gnu.org/software/coreutils/coreutils.html, +GNU Coreutils package}), you can use that program instead of ptys. + +Note also that ptys are not fully transparent. Certain binary control +codes, such @kbd{Ctrl-d} for end-of-file, are interpreted by the tty +driver and not passed through. + +@quotation CAUTION +Finally, coprocesses open up the possibility of @dfn{deadlock} between +@command{gawk} and the program running in the coprocess. This can occur +if you send ``too much'' data to the coprocess before reading any back; +each process is blocked writing data with noone available to read what +they've already written. There is no workaround for deadlock; careful +programming and knowledge of the behavior of the coprocess are required. +@end quotation @node TCP/IP Networking @section Using @command{gawk} for Network Programming |