chmod - change mode
chmod mode file ...
The mode of each named file is changed according to mode, which may be
an octal number or a symbolic change to the existing mode. A mode is
an octal number constructed from the OR of the following modes.
0400 read by owner
0200 write by owner
0100 execute (search in directory) by owner
0070 read, write, execute (search) by group
0007 read, write, execute (search) by others
A symbolic mode has the form:
[who] op permission
The who part is a combination of the letters u (for user's permis‐
sions), g (group) and o (other). The letter a stands for ugo. If who
is omitted, the default is a.
Op can be + to add permission to the file's mode, - to take away per‐
mission, and = to assign permission absolutely (all other bits will be
Permission is any combination of the letters r (read), w (write), x
(execute), a (append only), l (exclusive access), and t (temporary
Only the owner of a file or the group leader of its group may change
the file's mode.
SEE ALSOls(1), stat(2), stat(5)CHMOD(1)