Bash - Exit parent script from child script

Question

I have a Bash parent script that on unexpected input calls an error logging child script that logs the error. I also want the execution to halt when the error occurs and the error script is called. But if I call exit from the error handling script it does not stop the parent script from executing. How may I go about stopping a parent script from a child?

Answer 1

try..

#normal flow
[[ $(check_error_condition) ]] && /some/error_reporter.sh || exit 1

so,

• when the error_reporter will exit with exit status > 0 the parent will terminate too
• if the error_reporter will exit with status = 0 the parent continues...

You don't want stop the parent from a child (the parents usually don't like this behavior) :), you instead want tell to parent - need stop and he will stop itself (if want) ;)

Answer 2

Try:

In parent script:

trap "echo exitting because my child killed me.>&2;exit" SIGUSR1

In child script:

kill -SIGUSR1 `ps --pid $$ -oppid=`; exit

---

Other way was:

In child script:

kill -9 `ps --pid $$ -oppid=`; exit

But, it is not recommended, because the parent needs to have some information about getting killed & thus do some cleanup if required.

---

Another way: Instead of calling the child script, exec it.

---

However, as pointed out in other answer, the cleanest way is to exit from parent, after the child returns.

Answer 3

Don't try to terminate the parent from the child. Instead call exit in the parent after the child script returned.

if [ condition ]; then
  /path/to/child.sh
  exit 1
fi

or shorter

[ condition ] && { /path/to/child.sh; exit 1; }

Answer 4

Extension to @anishsane comment because MacOS has little bit different ps syntax.

Finding parent process ID (ppid) in child script under Mac OS (Darwin):

kill -SIGUSR1 $(ps $$ -o ppid=);exit

Answer 5

Depending on your needs, using set -e at the top of your script might be a good solution. This will automatically cause the script to exit if any commands (e.g., your error checking script) exit with a non-zero exit code (https://vaneyckt.io/posts/safer_bash_scripts_with_set_euxo_pipefail/)

Note that there are some common commands that have non zero exit codes under normal circumstance.