What does the -p flag do in "mkdir -p"?

Question

What does the -p flag do in mkdir -p?

Answer 1

The -p flag will create nested directories, but only if they don't exist already.

For example, suppose you have a directory /foo that you have write permissions for.

mkdir -p /foo/bar/baz  # creates bar and baz within bar under existing /foo

It is also an idempotent operation, because if you run the same command over again, you will not get an error, but nothing will be created.