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 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.

Setting Permissions    Basic operations on permissions.
Copying Permissions    Copying existing permissions.
Changing Special Mode Bits    Special mode bits.
Conditional Executability    Conditionally affecting executability.
Multiple Changes    Making multiple changes.
Umask and Protection    The effect of the umask.