chmod(1)

     NAME
          chmod - change the access permissions of files

     SYNOPSIS
          chmod [-Rcfv] [--recursive] [--changes] [--silent] [--quiet]
          [--verbose] [--help] [--version] mode file...

     DESCRIPTION
          This documentation is no longer being maintained and may be
          inaccurate or incomplete.  The Texinfo documentation is now
          the authoritative source.

          This manual page documents the GNU version of chmod.  chmod
          changes the permissions of each given file according to
          mode, which can be either a symbolic representation of
          changes to make, or an octal number representing the bit
          pattern for the new permissions.

          The format of a symbolic mode is `[ugoa...][[+-
          =][rwxXstugo...]...][,...]'.  Multiple symbolic operations
          can be given, separated by commas.

          A combination of the letters `ugoa' controls which users'
          access to the file will be changed: the user who owns it
          (u), other users in the file's group (g), other users not in
          the file's group (o), or all users (a).  If none of these
          are given, the effect is as if `a' were given, but bits that
          are set in the umask are not affected.

          The operator `+' causes the permissions selected to be added
          to the existing permissions of each file; `-' causes them to
          be removed; and `=' causes them to be the only permissions
          that the file has.

          The letters `rwxXstugo' select the new permissions for the
          affected users: read (r), write (w), execute (or access for
          directories) (x), execute only if the file is a directory or
          already has execute permission for some user (X), set user
          or group ID on execution (s), save program text on swap
          device (t), the permissions that the user who owns the file
          currently has for it (u), the permissions that other users
          in the file's group have for it (g), and the permissions
          that other users not in the file's group have for it (o).

          A numeric mode is from one to four octal digits (0-7),
          derived by adding up the bits with values 4, 2, and 1.  Any
          omitted digits are assumed to be leading zeros.  The first
          digit selects the set user ID (4) and set group ID (2) and
          save text image (1) attributes.  The second digit selects
          permissions for the user who owns the file: read (4), write
          (2), and execute (1); the third selects permissions for
          other users in the file's group, with the same values; and
          the fourth for other users not in the file's group, with the
          same values.

          chmod never changes the permissions of symbolic links; the
          chmod system call cannot change their permissions.  This is
          not a problem since the permissions of symbolic links are
          never used.  However, for each symbolic link listed on the
          command line, chmod changes the permissions of the pointed-
          to file.  In contrast, chmod ignores symbolic links
          encountered during recursive directory traversals.

        OPTIONS
          -c, --changes
               Verbosely describe only files whose permissions
               actually change.

          -f, --silent, --quiet
               Do not print error messages about files whose
               permissions cannot be changed.

          -v, --verbose
               Verbosely describe changed permissions.

          -R, --recursive
               Recursively change permissions of directories and their
               contents.

          --help
               Print a usage message on standard output and exit
               successfully.

          --version
               Print version information on standard output then exit
               successfully.