This exception is raised when one of the following functions is called with a non-directory argument

make_dir ?mode ?p filename creates a directory filename, if it does not already exist. It fails with NotADirectory if the file already exists, but is not a directory. The mode argument is the Unix permissions (0o755 by default). The p argument controls whether parents directories should be created as well, if they don't exist, instead of failing.

remove_dir ?all filename removes directory filename, or complains the NotADirectory if it does not exist. The all argument controls whether the function should recursively remove all files and sub-directories included as well. If glob is specified, it is called to select files to remove, and the directories are not deleted even if all is true.

select ?deep ?dft ?glob ?filter ?follow_links ?error () creates a selctor to customize a file iterator.

The deep and dft arguments controls whether function should recurse in sub-directories. If deep is true, and ~dft is not specified, the files are listed in breadth-first mode (a,b,a/x,b/x,a/x/y for example). If ~dft is `Before, the files are listed in depth-first mode, and the ancestors are before their children. If ~dft is `After, the are after their children.

The glob argument can be used to filter the basenames of files with a regular expression.

The filter argument is called as filter is_dir basename path where is_dir is set when checking whether to enter or not into a sub-directory, basename is the basename of the file and path is the path starting with a '/', yet relative to the initial directory. filter is called on every file with is_dir false to decide whether it should be added or not, and only on sub-directories with is_dir true to decide whether to enter or not if deep is true.

The follow_links argument is used to decide if a link to directory should be followed (when deep is also set).

The error argument is called when an error occurs, with error exn path filename.

read_dir ?select filename returns the files contained in the directory filename.

In a directory, files are sorted in lexicographical order of their names.

Same as read_dir, but returns a list instead of an array

Same as read_dir, but calls a function on every file and directory with the basename, the relative path (yet, starting with a '/') and the filename (i.e. the directory name concatenated with the relative path): f basename path file. It is not equivalent to using read_dir and then itering on the result, as iter_dir the function is called during the traversal, not after.

iterator ?select dir creates an iterator on directory dir. The iterator is a function that returns None when finished, or Some (path, filename) with the next file to iter on.

mkdir filename mode simply creates the directory filename with permissions mode.

readdir filename returns the files contained in directory filename as an array of strings. The strings are sorted in lexicographical order.

rmdir filename removes directory filename, or fails if it does not exist or is not a directory.