Info Catalog coreutils: Symbolic Modes coreutils: Copying Permissions

coreutils: Setting Permissions

 
 27.2.1 Setting Permissions
 --------------------------
 
 The basic symbolic operations on a file’s permissions are adding,
 removing, and setting the permission that certain users have to read,
 write, and execute or search the file.  These operations have the
 following format:
 
      USERS OPERATION PERMISSIONS
 
 The spaces between the three parts above are shown for readability only;
 symbolic modes cannot contain spaces.
 
    The USERS part tells which users’ access to the file is changed.  It
 consists of one or more of the following letters (or it can be empty;
 ⇒Umask and Protection, for a description of what happens then).
 When more than one of these letters is given, the order that they are in
 does not matter.
 
 ‘u’
      the user who owns the file;
 ‘g’
      other users who are in the file’s group;
 ‘o’
      all other users;
 ‘a’
      all users; the same as ‘ugo’.
 
    The OPERATION part tells how to change the affected users’ access to
 the file, and is one of the following symbols:
 
 ‘+’
      to add the PERMISSIONS to whatever permissions the USERS already
      have for the file;
 ‘-’
      to remove the PERMISSIONS from whatever permissions the USERS
      already have for the file;
 ‘=’
      to make the PERMISSIONS the only permissions that the USERS have
      for the file.
 
    The PERMISSIONS part tells what kind of access to the file should be
 changed; it is normally zero or more of the following letters.  As with
 the USERS part, the order does not matter when more than one letter is
 given.  Omitting the PERMISSIONS part is useful only with the ‘=’
 operation, where it gives the specified USERS no access at all to the
 file.
 
 ‘r’
      the permission the USERS have to read the file;
 ‘w’
      the permission the USERS have to write to the file;
 ‘x’
      the permission the USERS have to execute the file, or search it if
      it is a directory.
 
    For example, to give everyone permission to read and write a regular
 file, but not to execute it, use:
 
      a=rw
 
    To remove write permission for all users other than the file’s owner,
 use:
 
      go-w
 
 The above command does not affect the access that the owner of the file
 has to it, nor does it affect whether other users can read or execute
 the file.
 
    To give everyone except a file’s owner no permission to do anything
 with that file, use the mode below.  Other users could still remove the
 file, if they have write permission on the directory it is in.
 
      go=
 
 Another way to specify the same thing is:
 
      og-rwx
 

Info Catalog coreutils: Symbolic Modes coreutils: Copying Permissions