chmod - change access mode for files

     chmod [-R] mode file ...


     -R   Change hierarchies recursively


     chmod 755 file      # Owner: rwx Group: r-x Others: r-x

     chmod +x file1 file2
                         # Make file1 and file2 executable

     chmod a-w file      # Make file read only

     chmod u+s file      # Turn on SETUID for file

     chmod -R o+w dir    # Allow writing for all files in dir


     The given mode is applied to each file in the file list. If the  -R  flag
     is  present,  the files in a directory will be changed as well.  The mode
     can be either absolute or symbolic. Absolute modes are given as an  octal
     number  that  represents  the new file mode. The mode bits are defined as

        4000    Set effective user id on execution to file's owner id
        2000    Set effective group id on execution to file's group id
        0400    file is readable by the owner of the file
        0200    writeable by owner
        0100    executable by owner
        0070    same as above, for other users in the same group
        0007    same as above, for all other users

     Symbolic modes modify the current file mode in a specified way. The  form

        [who] op permissions { op permissions ...} {, [who] op ... }

     The possibilities for who are u, g, o, and a, standing for  user,  group,
     other  and  all,  respectively.  If who is omitted, a is assumed, but the
     current umask is used. The op can be +, -, or =;  + turns  on  the  given
     permissions, - turns them off; = sets the permissions exclusively for the
     given who. For example g=x sets the group permissions to --x.

     The possible permissions are r, w, x; which stand for  read,  write,  and
     execute;   s  turns on the set effective user/group id bits. s only makes
     sense with u and g; o+s is harmless.

     ls(1), chmod(2).