How to find whether or not a variable is empty in Bash

Question

How can I check if a variable is empty in Bash?

Answer 1

This will return true if a variable is unset or set to the empty string ("").

if [ -z "$MyVar" ]
then
   echo "The variable MyVar has nothing in it."
elif ! [ -z "$MyVar" ]
then
   echo "The variable MyVar has something in it."
fi