Bash Variable Empty

Here’s how to check in Bash if a variable is empty or unset.

<pre lang="bash">
if [ -z "${VAR}" ]; 
then
  echo 'do something'
else
  echo 'do another'
fi

One liner

<pre lang="bash">
if [ -z "${VAR}" ]; then echo 'do something'; else echo 'do another'; fi

The inverse

<pre lang="bash">
if [ ! -z "${VAR}" ]; 
then
  echo 'do something'
else
  echo 'do another'
fi

<pre lang="bash">
if [ ! -z "${VAR}" ]; then echo 'do something'; else echo 'do another'; fi