Introduction

Constantly while using bash scripts I write, some command halfway through the script will fail. With set -euo pipefail, at least it will cleanly exit rather than continuing in a broken state. But I often don't want to rerun the entire script, either because the part that already executed took actions that I don't want to repeat, or simply the part that already ran took a while and I don't want to wait for it to run again. So I often find myself copy pasting snippets from the first part of the script to get all the variables set to what they would be at the time of the crash, and then copy pasting to run the remainder of the script. Inspired by Common Lisp, where you enter the debugger on error and have various options for fixing and resuming your program, I decided to make a really poor imitation for bash. In the same situations where set -e would exit on error, this will open a menu giving you a few options for fixing the error and resuming the script without restarting it.

Installation

git clone https://github.com/sczi/bash_error_handler
echo "export BASH_ENV=$PWD/bash_error_handler/hook.sh" >> ~/.bashrc
source ~/.bashrc

This should install the error handler menu for scripts that are run from interactive terminals, without interfering with normal interactive shell usage or affecting scripts not run from interactive terminals.

Restart Options

Retry

This will simply rerun the command that failed (exited with a non-zero status). Then if it still fails, you'll get the restart menu again, while if it succeeds then your script will continue where it left off. For example imagine a script like:

echo Many long and complex actions
# Some command using internet
curl https://httpbin.org/get
echo Many more long and complex actions

If the curl command fails because our internet was down at the time, we can just connect our internet, choose Retry and the script should continue fine.

You can also imagine other situations where Retry would be enough to fix the problem. For example if a needed file was missing or some config file it tries to load or script it tries to run had a syntax error, then we can fix the file and hit Retry and our shell script will continue where it left off.

Edit command and retry

This will open the command that failed in EDITOR (or nano if EDITOR is unset). After you save the file and quit the editor, it will try to run your new command and continue the script. For example in a recent script, I was downloading videos, and a couple didn't support the format I was downloading the rest in. Rather then the script erroring out and having to restart the whole thing, I could just use Edit command and retry, list what formats are available, and edit the command to download an available format.

URL="$1"
echo Many long and complex actions
yt-dlp -f http-540p "$URL"
echo Many more long and complex actions.

Spawn shell

If you need to take more complicated actions to fix or debug the problem, this will spawn a subshell with all variables and functions defined as they are at the time of error in the script. When you exit the subshell, you'll get the restart menu again.

URL="$1"
echo Many long and complex actions
yt-dlp -f http-540p "$URL"
echo Many more long and complex actions.

Continue (ignoring error)

If the error shouldn't be fatal, you can choose this to simply continue the execution of your script.

echo Many long and complex actions
false
echo Many more long and complex actions

Abort (exit shell)

If the error is unrecoverable and you want to exit the script, choose this. This will give you the same effect as set -e, exiting at the error.

echo Many long and complex actions
false
echo Many more long and complex actions

Note it exited after false, and the final echo statement never ran.

Demo videos recorded with VHS