Re: 'wait -n' with and without id arguments

[Chet Ramey]

On 7/31/24 3:52 PM, Zachary Santer wrote:
> On Wed, Jul 31, 2024 at 11:40 AM Zachary Santer <zsanter@gmail.com> wrote:
> > Configuration Information [Automatically generated, do not change]:
> > Machine: x86_64
> > OS: msys
> > Compiler: gcc
> > Compilation CFLAGS: -g -O2
> > uname output: MSYS_NT-10.0-19045 Zack2021HPPavilion
> > 3.5.3-d8b21b8c.x86_64 2024-07-09 18:03 UTC x86_64 Msys
> > Machine Type: x86_64-pc-msys
> >
> > Bash Version: 5.3
> > Patch Level: 0
> > Release Status: alpha
> >
> > See attached.
>
> When I was executing the script normally, not sourcing it, in that
> email, that was bash 5.2.26(1)-release. To avoid confusion, please
> reference the attachments to this email instead.

OK, I see what's happening. When the shell is interactive, it notifies
the user when a background job terminates and prints a message to the
terminal. That's the series of

[2]   Done                    random_sleep

messages you see.

Once that happens, the shell considers the job `notified' and removes it
from the jobs table. That's when it moves to the list of saved background
pids and statuses. It's available there for `wait' when you supply a pid
argument, but no longer eligible to be returned by `wait -n' without
arguments, since it's already terminated and the user has been notified of
the status.

When I source your script on macOS with the current devel build, I get the
set of notification messages and termination with a false argument, and an
infinite loop with a true argument.

--
``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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