Re: Cleaning up background processes

On 08.05.2024 23:04, vallor wrote:

On Mon, 6 May 2024 12:08:39 -0000 (UTC), gazelle@shell.xmission.com (Kenny
McCormack) wrote in <v1ah87$l0a8$1@news.xmission.com>:
 

In article <20240505214609.114@kylheku.com>,
Kaz Kylheku  <643-408-1753@kylheku.com> wrote:

On 2024-05-05, Christian Weisgerber <naddy@mips.inka.de> wrote:

Is there a standard POSIX shell idiom to clean up background
processes?
>
You have a shell script that starts some background process with &.
Now you want to make sure that the background process terminates when
the shell script terminates.  In particular, when it terminates due to
special circumstances.

>
Maybe have an EXIT trap which calls wait?

'wait' wouldn't abort the process (as the OP seems to have required).

>
The fundamental underlying problem here is that the EXIT trap is only
called on a "normal" exit.  In particular, it does not get called under
(at least) the following circumstances:
>
    1) User hits ^C causing the script to abort.

 
I'm sorry, but I've waited and nobody said anything, so

I hadn't answered because it doesn't work as had been advertised. With

  trap 'echo INT' INT
  trap 'echo EXIT' EXIT

and hitting ^C I get both signals (INT) and pseudo-signal (EXIT)
in that order (with ksh, bash) [and it makes of course sense]

  INT
  EXIT

so it would be no problem, in my book.

But the pseudo-signal 'EXIT' is non-standard (to my knowledge), so you
cannot generally rely on it, depending on your environment, and the OP
asked for a "standard POSIX shell idiom".

I have to ask:  Why couldn't you trap "kill -1 0" INT?

Storing PIDs and killing the respective processes on exit is something
I had done in the past, making use of the process groups is something
I'd also consider; both things you already proposed upthread, IIRC.

Janis

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