Last Updated: 2024-04-15

I encounted this code in a Dockerfile entrypoint bash script. What is the usual purpose of such code?

if [ -z "$1" ]; then
  # do something 
fi

Technically, this checks if $1 is empty. And why does that matter? Because, in effect, this checks if there are 0 arguments to the script. This can be used for validating input arguments or for taking alternate actions depending on argument count.