Re: SIGINT handling during async functions

[Tycho Kirchner]

Am 13.01.23 um 03:02 schrieb Robert Elz:
>      Date:        Fri, 13 Jan 2023 00:34:02 +0100
>      From:        Tycho Kirchner <tychokirchner@mail.de>
>      Message-ID:  <7d59c17d-792e-0ac7-fd86-b3b2e7d4b79a@mail.de>
>
>    | we found quite some inconsistency and weirdness
>    | in the handling of SIGINT's during async function calls
>
> Not inconsistent or weird, and has nothing to do with
> function calls.
>
>    | and were wondering, whether those are expected.
>
> Expected and required.
>
>    | The main INT handler is never executed in foofunc [...]
>    | Thus printing the trap apparently changes bash's behavior.
>
> Nonsense (the conclusion)> 
> When an async command (any command, not just functions,
> or blocks enclosed in { } ) is run with job control
> disabled, SIGINT is ignored for that async command.
> (SIGQUIT too).
>
> That has been the way shells work since before either
> the Bourne shell (and all later shells based upon it,
> like bash) or job control, were invented.
>
> That is all you are seeing here.
>
> kre

Dear Robert Elz,
thanks for the quick response. However, did you actually actually put the short 
snippets into a script, executed it and verified that their behavior is the 
same? In particular, did you check, whether the respective 'sleep' commands 
kept running, after hitting Ctrl+C? On my test system, the 'sleep 3' within 
foofounc **is** killed in the first three code snippets, proving your 
statements wrong. **Only** in case of the 4th snippet, where the trap is 
printed at the beginning of foofunc, the 'sleep 3' command keeps running after 
hitting Ctrl+C.
Let me give another example. Put the following commands into a script test.sh 
and execute it.
______________________________________
bash -c 'echo first; trap -p' & wait
{ bash -c 'echo second; trap -p'; } & wait
{ trap -p >/dev/null; bash -c 'echo third; trap -p'; } & wait
______________________________________

$ ./test.sh
first
trap -- '' SIGINT
trap -- '' SIGQUIT
second
third
trap -- '' SIGINT
______________________________________

So, even in this simple case, differences are observable.
Kind regards
Tycho