FEATURE REQUEST : shell option to automatically terminate child processes on parent death

[Corto Beau]

Configuration Information [Automatically generated, do not change]:
Machine: x86_64
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS: -g -O2
uname output: Linux zinc 6.6.1-arch1-1 #1 SMP PREEMPT_DYNAMIC Wed, 08 
Nov 2023 16:05:38 +0000 x86_64 GNU/Linux
Machine Type: x86_64-pc-linux-gnu

Bash Version: 5.2 Patch
Level: 21
Release Status: release

Description:
Hi,

I would like to suggest a new shell option to ensure child processes are 
automatically killed when the parent dies.

Right now, it's already possible to emulate this feature by setting a 
trap to kill all child processes on exit (trap "kill 0" EXIT), but 
obviously it doesn't work if the process is terminated by a signal that 
cannot be caught (like SIGKILL).

On Linux, it can be done by setting the PR_SET_PDEATHSIG flag to 
propagate the parent termination signal to the child, regardless of 
whether the signal can be caught or not.

The rationale for this feature is that scripts spawning background 
processes to listen to various events (udev events, window manager 
events, etc) often leave orphan processes behind when terminated forcefully.

I've attached a proof-of-concept patch.

no_reparent.patch
Description: Text Data