The disappointment with set -e is that it does not work everywhere: - with an unset 'hello' variable, try: set -eu echo "`echo $hello` world" echo "huh

The disappointment with set -e is that it does not work everywhere: - with an unset 'hello' variable, try: set -eu echo "`echo $hello` world" echo "huh still going?!" foo="`echo $hello` world" echo "not reaching this as expected" Fun, now you have to manually write your whole program in what's basically SSA (static single assignment) form. - It's deactivated in if/then context, which at first makes sense, but then when you try to force it on explicitely like: set -eu if (set -eu; false; true); then echo "huh why still true??" else echo false fi and your declaration is just ignored.. you begin to wonder how many places set -e misses really.