-errexit: exit the script when a command fails -nounset: fail when referencing an unset variable -pipefail: fail when the any command in a pipeline fails, not just the last one

The last option is unfortunately harder to use, since some programs misbehave in pipelines.

set -o errexit (set -e): exit script when command fails

set -o nounset (set -u): exit script when it tries to use undeclared variables

set -o pipefail: returns error from pipe `|` if any of the commands in the pipe fail (normally just returns an error if the last fails)

The "shebang" treats everything after the binary as a single argument. It only does one argument from the shebang and the file itself as the final argument. So it would run that kinda like

    bash '-e -u' $file

But you can do

    #!/bin/bash -eu

This breaks if your script is sourced by another shell. Best use 'set -eu' at the start instead.

You can save a line by doing #!/bin/bash -eu