File::Spec->canonpath

Does logical cleanup of path.

File::Spec->catdir(dir[, dir...])

Concatenates two or more directory names to form a complete path. Ends with a directory name.

File::Spec->catfile(dir[, dir...], file)

Concatenates one or more directory names and a filename to form a complete path that ends with a filename.

File::Spec->curdir

Returns ., representing the current directory.

File::Spec->file_name_is_absolute(path)

Takes a path as argument and returns true if it is an absolute path.

File::Spec->join(dir[, dir...], file)

Same as catfile.

File::Spec->no_upwards(files)

Strips names of files referring to a parent directory from a list of filenames. Doesn't strip symbolic links.

File::Spec->path

Returns the PATH environment variable as an array.

File::Spec->rootdir

Returns /, representing the root directory.

File::Spec->updir

Returns .., representing the parent directory.