Re: waiting for process substitutions

[Chet Ramey]

On 7/2/24 9:59 PM, Zachary Santer wrote:

> I *am* seeing a difference between having lastpipe enabled (and job
> control off) or not when running your example in the interactive
> shell, though:
> SECONDS=0; echo $'foo\nbar' | tee >(echo first ; exit 1) >(wc ; sleep
> 10 ; echo wc) >(tail -n 1; echo tail); wait; printf '%s\n'
> "SECONDS=${SECONDS}"
>
> With lastpipe disabled, wait exits immediately.

There are no process substitutions or asynchronous processes for `wait'
to return, since the last pipeline element containing the procsubs is
executed in a child process.

> With lastpipe enabled,
> it does seem to wait for everything.

The last pipeline element is executed in the current environment, and
any side effects persist in the current environment, so you have process
substitutions for `wait' to return.

I didn't look at the script behavior, since you don't have any pipelines
where lastpipe might have an effect.

--
``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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