If `set -u` is enabled, the aforementioned test will fail on unset variables. To avoid this, you can "declare" `var` at the beginning of the script, e.g. `var=

If `set -u` is enabled, the aforementioned test will fail on unset variables. To avoid this, you can "declare" `var` at the beginning of the script, e.g. `var=''`. Also instead of `[ ! -z "$var" ]` I prefer `[ -n "$var" ]`, which is the same as `[ "$var" ]` but more explicit.