Re: process substitution error handling

From	Chet Ramey <chet.ramey@case.edu>
Newsgroups	gnu.bash.bug
Subject	Re: process substitution error handling
Date	2020-08-06 11:14 -0400
Organization	ITS, Case Western Reserve University
Message-ID	<mailman.1027.1596726900.2739.bug-bash@gnu.org> (permalink)
References	(2 earlier) <CAHmME9pzOY_0EJ69y9wt6r-Jh3frZpV8XdFC6zG5EOkZ99h-1A@mail.gmail.com> <ac79e09f-b4e3-5368-87c1-b6e7147809e2@case.edu> <CAHmME9qNjO+LMxB8py2MDpS2Oprv1mRndgfTXQfXNWyHuwzmjg@mail.gmail.com> <9b358a76-4867-41b9-5a3a-c1892c76b8ee@case.edu> <d27db25d-e533-3fa8-b85e-6dfbe6adefb3@case.edu>

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On 8/6/20 10:48 AM, Chet Ramey wrote:

>> Perhaps another, clunkier, proposal would be to add `wait -s` so that
>> the wait builtin also waits for process substitutions and returns
>> their exit codes and changes $?. The downside would be that scripts
>> now need to add a "wait" after all of above such loops, but on the
>> upside, it's better than the current problematic situation.
> 
> You can already do this. Since process substitution sets $!, you can
> keep track of all of the process substitutions of interest and wait
> for as many of them as you like. `wait' will return their statuses
> and set $? for you.

I should have also mentioned that while bash-5.0 requires you to wait
for these process substitutions one at a time, in between their creation,
bash-5.1 will allow you to save $! and wait for them later:

$ cat x2
: <(sleep 5; exit 1)
P1=$!

: <(sleep 5; exit 2)
P2=$!

: <(sleep 5; exit 3)
P3=$!

wait $P1 ; echo $?
wait $P2 ; echo $?
wait $P3 ; echo $?
$ ../bash-5.1-alpha/bash x2
1
2
3


-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
		 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/

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Re: process substitution error handling Chet Ramey <chet.ramey@case.edu> - 2020-08-06 11:14 -0400

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