coreutils: Operator Numeric Modes
27.4 Operator Numeric Modes
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An operator numeric mode is a numeric mode that is prefixed by a ‘-’,
‘+’, or ‘=’ operator, which has the same interpretation as in symbolic
modes. For example, ‘+440’ enables read permission for the file’s owner
and group, ‘-1’ disables execute permission for other users, and ‘=600’
clears all permissions except for enabling read-write permissions for
the file’s owner. Operator numeric modes can be combined with symbolic
modes by separating them with a comma; for example, ‘=0,u+r’ clears all
permissions except for enabling read permission for the file’s owner.
The commands ‘chmod =755 DIR’ and ‘chmod 755 DIR’ differ in that the
former clears the directory DIR’s setuid and setgid bits, whereas the
latter preserves them. ⇒Directory Setuid and Setgid.
Operator numeric modes are a GNU extension.
Info Catalog
coreutils: Numeric Modes
coreutils: File permissions
coreutils: Directory Setuid and Setgid