Traps in bash listen for interrupts and signals and performs a bash command in response to it. This post will go over three use cases I've encountered so far in my bash scripting journey.
## `SIGINT`
If we have a while loop within a bash script
```bash
while sleep 0.1; do
do_something
done
```
We probably want to be able to CTRL-C to exit the whole script.
```bash
finish () {
exit 0
}
trap finish SIGINT
while sleep 0.1; do
do_something
done
```
## `ERR`
If we encounter an error in a bash script, one thing we might want to do is dump the environment information and other things that can be useful for debugging.
```bash
set -o errexit
set -o nounset
set -o pipefail
print_debug () {
declare exit_code=$?
env >&2
other_debug_info >&2
exit "$exit_code"
}
trap print_debug ERR
command_that_may_fail
```
## `EXIT`
Like the last one, this function will occur if the script fails. However, this also occurs if the script is successful. It's similar to the `finally` clause within a `try-catch` programming paradigm.
This is useful for cleaning up build files, de-provisioning services, etc.
