Merge branch 'master' into feature/cmake

1 files changed, 18 insertions, 0 deletions

diff --git a/doc/gawktexi.in b/doc/gawktexi.in
index e43d7137..f47c8459 100644
--- a/doc/gawktexi.in
+++ b/doc/gawktexi.in
@@ -26944,6 +26944,24 @@ As a side note, the assignment @samp{LC_ALL=C} in the @command{sort}
 command ensures traditional Unix (ASCII) sorting from @command{sort}.
 This is not strictly necessary here, but it's good to know how to do this.
 
+Be careful when closing the @code{"from"} end of a two-way pipe; in this
+case @command{gawk} waits for the child process to exit, which may cause
+your program to hang.  (Thus, this particular feature is of much less
+use in practice than being able to close the @code{"to"} end.)
+
+@quotation CAUTION
+Normally,
+it is a fatal error to write to the @code{"to"} end of a two-way
+pipe which has been closed, and it is also a fatal error to read
+from the @code{"from"} end of a two-way pipe that has been closed.
+
+You may set @code{PROCINFO["@var{command}", "NONFATAL"]} to
+make such operations become nonfatal, in which case you then need
+to check @code{ERRNO} after each @code{print}, @code{printf},
+or @code{getline}.
+@xref{Nonfatal}, for more information.
+@end quotation
+
 @cindex @command{gawk}, @code{PROCINFO} array in
 @cindex @code{PROCINFO} array, and communications via ptys
 You may also use pseudo-ttys (ptys) for