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Diffstat (limited to 'doc/gawktexi.in')
| -rw-r--r-- | doc/gawktexi.in | 18 |
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 |