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)