coreutils: chgrp invocation

1 
1 13.2 ‘chgrp’: Change group ownership
1 ====================================
1 
1 ‘chgrp’ changes the group ownership of each given FILE to GROUP (which
1 can be either a group name or a numeric group ID) or to the group of an
1 existing reference file.  ⇒chown invocation.  Synopsis:
1 
1      chgrp [OPTION]... {GROUP | --reference=REF_FILE} FILE...
1 
1    If GROUP is intended to represent a numeric group ID, then you may
1 specify it with a leading ‘+’.  ⇒Disambiguating names and IDs.
1 
1    It is system dependent whether a user can change the group to an
1 arbitrary one, or the more portable behavior of being restricted to
1 setting a group of which the user is a member.
1 
11    The program accepts the following options.  Also see ⇒Common
 options.
1 
1 ‘-c’
1 ‘--changes’
1      Verbosely describe the action for each FILE whose group actually
1      changes.
1 
1 ‘-f’
1 ‘--silent’
1 ‘--quiet’
1      Do not print error messages about files whose group cannot be
1      changed.
1 
1 ‘--dereference’
1      Do not act on symbolic links themselves but rather on what they
1      point to.  This is the default when not operating recursively.
1 
1      Combining this dereferencing option with the ‘--recursive’ option
1      may create a security risk: During the traversal of the directory
1      tree, an attacker may be able to introduce a symlink to an
1      arbitrary target; when the tool reaches that, the operation will be
1      performed on the target of that symlink, possibly allowing the
1      attacker to escalate privileges.
1 
1 ‘-h’
1 ‘--no-dereference’
1      Act on symbolic links themselves instead of what they point to.
1      This mode relies on the ‘lchown’ system call.  On systems that do
1      not provide the ‘lchown’ system call, ‘chgrp’ fails when a file
1      specified on the command line is a symbolic link.  By default, no
1      diagnostic is issued for symbolic links encountered during a
1      recursive traversal, but see ‘--verbose’.
1 
1 ‘--preserve-root’
1      Fail upon any attempt to recursively change the root directory,
11      ‘/’.  Without ‘--recursive’, this option has no effect.  ⇒
      Treating / specially.
1 
1 ‘--no-preserve-root’
11      Cancel the effect of any preceding ‘--preserve-root’ option.  ⇒
      Treating / specially.
1 
1 ‘--reference=REF_FILE’
1      Change the group of each FILE to be the same as that of REF_FILE.
1      If REF_FILE is a symbolic link, do not use the group of the
1      symbolic link, but rather that of the file it refers to.
1 
1 ‘-v’
1 ‘--verbose’
1      Output a diagnostic for every file processed.  If a symbolic link
1      is encountered during a recursive traversal on a system without the
1      ‘lchown’ system call, and ‘--no-dereference’ is in effect, then
1      issue a diagnostic saying neither the symbolic link nor its
1      referent is being changed.
1 
1 ‘-R’
1 ‘--recursive’
1      Recursively change the group ownership of directories and their
1      contents.
1 
1 ‘-H’
1      If ‘--recursive’ (‘-R’) is specified and a command line argument is
11      a symbolic link to a directory, traverse it.  ⇒Traversing
      symlinks.
1 
1 ‘-L’
1      In a recursive traversal, traverse every symbolic link to a
1      directory that is encountered.
1 
1      Combining this dereferencing option with the ‘--recursive’ option
1      may create a security risk: During the traversal of the directory
1      tree, an attacker may be able to introduce a symlink to an
1      arbitrary target; when the tool reaches that, the operation will be
1      performed on the target of that symlink, possibly allowing the
1      attacker to escalate privileges.
1 
1      ⇒Traversing symlinks.
1 
1 ‘-P’
1      Do not traverse any symbolic links.  This is the default if none of
1      ‘-H’, ‘-L’, or ‘-P’ is specified.  ⇒Traversing symlinks.
1 
1    An exit status of zero indicates success, and a nonzero value
1 indicates failure.
1 
1    Examples:
1 
1      # Change the group of /u to "staff".
1      chgrp staff /u
1 
1      # Change the group of /u and subfiles to "staff".
1      chgrp -hR staff /u
1