Description

   The dirname function takes a pointer to a character string that
   contains a UNIX pathname and returns a pointer to a string that
   is a pathname of the parent directory of that file. Trailing
   slash (/)  characters in the path are not counted as part of the
   path.

   This function returns a pointer to the string "." (dot), when the
   path argument:

   o  Does not contain a slash (/).

   o  Is a NULL pointer.

   o  Points to an empty string.

   The dirname function can modify the string pointed to by the path
   argument.

   The dirname and basename functions together yield a complete
   pathname. The expression dirname(path) obtains the pathname of
   the directory where basename(path) is found.

   See also basename.