Mac OS X in a Nutshell

Name

chmod

Synopsis

chmod [option] mode 
                     files
                  

Changes the access mode of one or more files. Only the owner of a file or a privileged user may change its mode. Create mode by concatenating the characters from who, opcode, and permission. who is optional (if omitted, default is a); choose only one opcode.

Options

-f

Suppress error message upon failure to change a file’s mode.

-H

If any of the pathnames given in the command line are symbolic links, follow only those links during recursive operation. Works only with the -R option.

-L

Follow all symbolic links during recursive operation. Works only with the -R option.

-P

Follow no symbolic links during recursive operation. Works only with the -R option (the default).

-R

Recursively descend directory arguments while setting modes.

Who

u

User

g

Group

o

Other

a

All (default)

Opcode

+

Add permission

-

Remove permission

=

Assign permission (and remove permission of the unspecified fields)

Permission

r

Read

w

Write

x

Execute (file) or search (directory)

X

Sets the execute bit for all who values if any of the execute bits are already set in the specified file; meaningful only in conjunction with the op symbol +

s

Set user (or group) ID

t

Sticky bit; save text mode (file) or prevent removal of files by nonowners (directory)

u

User’s present permission

g

Group’s present permission

o

Other’s present permission

Alternatively, specify permissions by a 3-digit sequence. The first digit designates owner permission; the second, group permission; ...