If you want to create a directory using bash (in the terminal), but you don’t know whether it’ll already exist so you only want to create it if the directory doesn’t exist yet:
mkdir -p directory
mkdir -p my/directory/here
You can use this with a top-level directory (the first example), or with a deeply nested directory (the second example).
-p flag creates all directories necessary along the way (for example
here) if they don’t exist yet.