CHMOD(1) CHMOD(1)
NAME
chmod - change mode
SYNOPSIS
chmod mode file ...
DESCRIPTION
The mode of each named file is changed according to mode,
which may be absolute or symbolic. An absolute mode is an
octal number constructed from the OR of the following modes:
4000 set user ID on execution
2000 set group ID on execution
1000 sticky bit, see chmod(2)
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 [op permission] ...
The who part is a combination of the letters u (for user's
permissions), g (group) and o (other). The letter a stands
for ugo. If who is omitted, the default is a but the setting
of the file creation mask (see umask(2)) is taken into
account.
Op can be + to add permission to the file's mode, - to take
away permission and = to assign permission absolutely (all
other bits will be reset).
Permission is any combination of the letters r (read), w
(write), x (execute), s (set owner or group id) and t (save
text - sticky). Letters u, g or o indicate that permission
is to be taken from the current mode. Omitting permission
is only useful with = to take away all permissions.
The first example denies write permission to others, the
second makes a file executable:
chmod o-w file
chmod +x file
Multiple symbolic modes separated by commas may be given.
Operations are performed in the order specified. The letter
s is only useful with u or g.
CHMOD(1) CHMOD(1)
Only the owner of a file (or the super-user) may change its
mode.
SEE ALSO
ls(1), chmod(2), stat(2), umask(2), chown(8)