bash check if variable is empty code example

Example 1: bash if null or empty

if [ -z "$variable" ];
  then echo "$variable is null";
  else echo "$variable is not null";
fi

Example 2: bash if variable is not empty

VAR=`echo Hello world`
if [[ -n "$VAR" ]] ; then echo "Variable is set" ; fi

Example 3: bash check if variable is empty

if [ -z "$var" ] #return true if $var is unset