I'm working on a Bash script that includes a function called `test_command`, which executes a command passed to it and checks whether it completed successfully. I'm wondering about the best way to handle error trapping in my script. Specifically, should I use one single trap for `EXIT`, or should I set up separate traps for `ERR` and `EXIT`? Between these two approaches, are there trade-offs I should consider? Also, where in my script should I handle the removal of an error log file? Lastly, I'd like to know if this setup is robust enough to scale for more complex commands like interacting with external systems (e.g., psql, AWS). Is there a specific design pattern in Bash that relates to this kind of error handling?
2 Answers
Honestly, it's best to avoid using `eval` in your scripts because it can lead to security issues. Most system-level commands will return an exit code that you can catch with `$?`, making `eval` unnecessary. Now, regarding your traps, it really depends on if you need different actions for successful exits versus error exits. Also, be careful with the `ERR` trap. It won't fire if the command is part of certain conditional structures. As for your log files, I recommend deleting them at the start rather than at the end of the process—it makes it easier to review errors if needed.
I see where you're going with this! But you can't forget that the `ERR` trap only runs on command failures, and with your current code, it's unlikely to trigger because you're handling errors directly. A more streamlined approach might be to use an `EXIT` trap to clean up and report errors at the end. You can format your error handling like this to keep it safe and clean. Using `set -o pipefail` can also help catch any issues from piped commands, which is a nice touch!
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