Set -euxo pipefail

To make working with Bash scripts less problematic, I've switched to these default shebang and settings:

#!/usr/bin/env bash
set -euxo pipefail

The first line tells the interpreter to run the file via bash as found at /usr/bin/env. This /usr/bin/env is one of the most platform-independent locations that I know (it even works on NixOS).

The second line makes it much easier to find problems in the script. The -e option will cause the script to fail immediately when a command fails, the -o pipefail will also crash if one of the commands in a pipe fails (this could have avoided a Cloudflare outage), -u will treat unset variables as error, and -x will print each command before execution.