EvalRelative evaluates symlinks in path relative to root path.

IsDir check if name component is a directory.

IsExec check if name component has executable bit permission set.

IsFile check if name component is regular file.

IsLink check if name component is a symlink.

IsOwner check if name component is owned by user identified with uid.

IsSuid check if name component has setuid bit permission set.

Mkdir creates a directory if it doesn't exist with mode after umask reset.

MkdirAll creates a directory and parents if it doesn't exist with mode after umask reset.

RootDir returns the root directory of path (rootdir of /my/path is /my).

Touch behaves like touch command.