From c7f049c503527c3dd64b2850e2e768bbcf26f2a8 Mon Sep 17 00:00:00 2001 From: Pádraig Brady Date: Fri, 20 Nov 2015 11:54:00 +0000 Subject: doc: give a tee example for combining process substitution outputs This can be useful if you want to further process data from process substitutions. For example: datagen | tee >(md5sum --tag) > >(sha256sum --tag) | sort * doc/coreutils.texi (tee invocation): Mention that -p is useful with pipes that may not consume all data. Add an example, similar to the one above. * THANKS.in: Add Jirka Hladky. --- doc/coreutils.texi | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'doc') diff --git a/doc/coreutils.texi b/doc/coreutils.texi index 8034807a4..0e28f4971 100644 --- a/doc/coreutils.texi +++ b/doc/coreutils.texi @@ -13019,6 +13019,11 @@ so it works with @command{zsh}, @command{bash}, and @command{ksh}, but not with @command{/bin/sh}. So if you write code like this in a shell script, be sure to start the script with @samp{#!/bin/bash}. +Note also that if any of the process substitutions (or piped stdout) +might exit early without consuming all the data, the @option{-p} option +is needed to allow @command{tee} to continue to process the input +to any remaining outputs. + Since the above example writes to one file and one process, a more conventional and portable use of @command{tee} is even better: @@ -13087,6 +13092,17 @@ tar chof - "$tardir" \ | bzip2 -9 -c > your-pkg-M.N.tar.bz2 @end example +If you want to further process the output from process substitutions, +and those processes write atomically (i.e., write less than the system's +PIPE_BUF size at a time), that's possible with a construct like: + +@example +tardir=your-pkg-M.N +tar chof - "$tardir" \ + | tee >(md5sum --tag) > >(sha256sum --tag) \ + | sort | gpg --clearsign > your-pkg-M.N.tar.sig +@end example + @exitstatus -- cgit v1.2.3-70-g09d2