1CHMOD(1) General Commands Manual CHMOD(1)
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6 chmod - change mode
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9 chmod mode file ...
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12 The mode of each named file is changed according to mode, which may be
13 absolute or symbolic. An absolute mode is an octal number constructed
14 from the OR of the following modes:
15 4000 set user ID on execution
17 2000 set group ID on execution
18 1000 sticky bit, see chmod(2)
19 0400 read by owner
20 0200 write by owner
21 0100 execute (search in directory) by owner
22 0070 read, write, execute (search) by group
23 0007 read, write, execute (search) by others
24 A symbolic mode has the form:
26 [who] op permission [op permission] ...
28 The who part is a combination of the letters u (for user's permis‐
30 sions), g (group) and o (other). The letter a stands for ugo. If who
31 is omitted, the default is a but the setting of the file creation mask
32 (see umask(2)) is taken into account.
33 Op can be + to add permission to the file's mode, - to take away per‐
35 mission and = to assign permission absolutely (all other bits will be
36 reset).
37 Permission is any combination of the letters r (read), w (write), x
39 (execute), s (set owner or group id) and t (save text - sticky). Let‐
40 ters u, g or o indicate that permission is to be taken from the current
41 mode. Omitting permission is only useful with = to take away all per‐
42 missions.
43 The first example denies write permission to others, the second makes a
45 file executable:
46 chmod o-w file
48 chmod +x file
49 Multiple symbolic modes separated by commas may be given. Operations
51 are performed in the order specified. The letter s is only useful with
52 u or g.
53 Only the owner of a file (or the super-user) may change its mode.
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57 ls(1), chmod(2), chown (1), stat(2), umask(2)
58 CHMOD(1)