CHMOD(1) CHMOD(1) NAME chmod - change mode SYNOPSIS chmod [ -Rf ] mode file ... DESCRIPTION The mode of each named file is changed according to _m_o_d_e, which may be absolute or symbolic. An absolute _m_o_d_e 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 _c_h_m_o_d(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 _m_o_d_e has the form: [_w_h_o] _o_p _p_e_r_m_i_s_s_i_o_n [_o_p _p_e_r_m_i_s_s_i_o_n] ... The _w_h_o part is a combination of the letters u (for user’s permis‐ sions), g (group) and o (other). The letter a stands for all, or ugo. If _w_h_o is omitted, the default is _a but the setting of the file cre‐ ation mask (see umask(2)) is taken into account. _O_p can be + to add _p_e_r_m_i_s_s_i_o_n to the file’s mode, - to take away _p_e_r_‐ _m_i_s_s_i_o_n and = to assign _p_e_r_m_i_s_s_i_o_n absolutely (all other bits will be reset). _P_e_r_m_i_s_s_i_o_n is any combination of the letters r (read), w (write), x (execute), X (set execute only if file is a directory or some other execute bit is set), s (set owner or group id) and t (save text - sticky). Letters u, g, or o indicate that _p_e_r_m_i_s_s_i_o_n is to be taken from the current mode. Omitting _p_e_r_m_i_s_s_i_o_n is only useful with = to take away all permissions. When the -R option is given, _c_h_m_o_d recursively descends its directory arguments setting the mode for each file as described above. When sym‐ bolic links are encountered, their mode is not changed and they are not traversed. If the -f option is given, _c_h_m_o_d will not complain if it fails to change the mode on a file. EXAMPLES The first example denies write permission to others, the second makes a file executable by all if it is executable by anyone: 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. 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) 7th Edition May 22, 1986 CHMOD(1)