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From: Greg Klanderman <gak@klanderman.net>
To: Zsh list <zsh-workers@zsh.org>
Subject: using trap function to cleanup and exit?
Date: Sun, 10 Apr 2022 11:46:25 -0400	[thread overview]
Message-ID: <25170.64465.301441.247673@lwm.klanderman.net> (raw)


I've been trying to ensure some cleanup is done when a script I'm
writing exits, whether normally, with an error, or when killed (other
than with -9, of course).

I had thought a try/always block would handle signals as well, but
it appears not.

So I've been trying to use either trap functions or the trap builtin
(list traps) with no success.

[zsh below is debian/5.8.1-1 (Debian testing)]

Here's a simple test script (the sleep has been substituted for an
external command that waits on a condition and outputs something; my
actual use case also has that within a loop):


#!/bin/zsh -f

cleanup () {
  echo "cleanup"

do_something () {
  echo "in do_something"
  local foo
  read -u 0 foo
  echo "done do_something"

  echo "in TRAPTERM"
  cleanup TERM
  exit $(( 128 + $1 ))

foo () {
  echo "in foo"
  sleep 1234567 | do_something



When run, it immediately prints:

| in foo
| in do_something

then when hit with SIGTERM:

| cleanup

however, the process and its child (sleep) remain running.

I expected both to exit.

Additionally, when I hit it with some other signal (SIGINT), the
script does get killed, however, the child sleep process remains.
Is that expected?

I tried TRAPEXIT as well, both at top level and within the function
foo, but that seems not to handle signals.

How can I ensure that a script and non-disowned children are killed
when a signal is received, after doing some cleanup?

Is there a way to do that for all appropriate signals, or do I have to
explicitly list the desired signals?

thank you,

             reply	other threads:[~2022-04-10 15:46 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-10 15:46 Greg Klanderman [this message]
2022-04-10 15:57 ` Peter Stephenson
2022-04-10 16:12   ` Greg Klanderman
2022-04-10 16:30     ` Greg Klanderman
2022-04-10 18:15       ` Lawrence Velázquez
2022-04-14  5:13         ` Greg Klanderman
2022-04-10 20:49       ` Bart Schaefer
2022-04-10 20:55         ` Bart Schaefer
2022-04-14  5:57         ` Greg Klanderman
2022-04-14 21:29           ` Bart Schaefer
2022-04-14 23:35             ` Bart Schaefer
2022-04-17 17:08               ` Daniel Shahaf
2022-04-15 22:27             ` Bart Schaefer
2022-04-19 18:42               ` Peter Stephenson
2022-04-19 18:55                 ` Peter Stephenson
2022-04-19 21:22                   ` Bart Schaefer
2022-04-20  8:16                     ` Peter Stephenson

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