Test for a Bash variable being unset, using a function

Question

A simple Bash variable test goes:

${varName:?    \"${varName} is not defined\"}

I\'d like to re-use this, by putting it in a function. How

Answer 1

Unsure if this is exactly what you want but a handy trick I use when writing a new+complex script is to use "set -o"

set -o #will make the script bomb out when it finds an unset variable

EG:

$ grep '$1' chex.sh

case "$1" in

$ ./chex.sh

./chex.sh: line 111: $1: unbound variable

$ ./chex.sh foo

incorrect/no options passed.. exiting