File.mkdir

You're seeing just the function mkdir, go back to File module for more information.

mkdir(path)

mkdir(Path.t()) :: :ok | {:error, posix()}

Tries to create the directory path.

Missing parent directories are not created. Returns :ok if successful, or {:error, reason} if an error occurs.

Typical error reasons are:

:eacces - missing search or write permissions for the parent directories of path
:eexist - there is already a file or directory named path
:enoent - a component of path does not exist
:enospc - there is no space left on the device
:enotdir - a component of path is not a directory; on some platforms, :enoent is returned instead