The path_basename function returns the basename associated
with the path parameter. The basename is the non-directory
part of the filename, e.g., on unix c is the basename of
/a/b/c.
The path_concat function combines the arguments dir and
basename to produce a pathname. For example, on unix is
dir is x/y and basename is z, then the
function will return x/y/z.
The path_extname function returns the extension portion of a
specified pathname. If an extension is present, this function will
also include the dot as part of the extension, i.e., if path
is file.c, then this function returns ".c". If no
extension is present, the function returns an empty string "".
Notes
Under VMS, the file version number is not returned as part of the
extension.