27.2 Symbolic Modes

Symbolic modes represent changes to files’ mode bits as operations on single-character symbols. They allow you to modify either all or selected parts of files’ mode bits, optionally based on their previous values, and perhaps on the current umask as well (see The Umask and Protection).

The format of symbolic modes is:


where perms is either zero or more letters from the set ‘rwxXst’, or a single letter from the set ‘ugo’.

The following sections describe the operators and other details of symbolic modes.