Test if a variable is set in bash when using “set -o nounset”

Question

The following code exits with a unbound variable error. How to fix this, while still using the set -o nounset option?

#!/bin/bash

set -o nounse         


        

Answer 1

You can use

if [[ ${WHATEVER:+$WHATEVER} ]]; then

but

if [[ "${WHATEVER:+isset}" == "isset" ]]; then

might be more readable.