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CHMOD(1)		FreeBSD	General	Commands Manual		      CHMOD(1)

NAME
     chmod -- change file modes

SYNOPSIS
     chmod [-fhv] [-R [-H | -L | -P]] mode file	...

DESCRIPTION
     The chmod utility modifies	the file mode bits of the listed files as
     specified by the mode operand.

     The options are as	follows:

     -f	     Do	not display a diagnostic message if chmod could	not modify the
	     mode for file, nor	modify the exit	status to reflect such fail-
	     ures.

     -H	     If	the -R option is specified, symbolic links on the command line
	     are followed.  (Symbolic links encountered	in the tree traversal
	     are not followed by default.)

     -h	     If	the file is a symbolic link, change the	mode of	the link
	     itself rather than	the file that the link points to.

     -L	     If	the -R option is specified, all	symbolic links are followed.

     -P	     If	the -R option is specified, no symbolic	links are followed.
	     This is the default.

     -R	     Change the	modes of the file hierarchies rooted in	the files
	     instead of	just the files themselves.

     -v	     Cause chmod to be verbose,	showing	filenames as the mode is modi-
	     fied.  If the -v flag is specified	more than once,	the old	and
	     new modes of the file will	also be	printed, in both octal and
	     symbolic notation.

     The -H, -L	and -P options are ignored unless the -R option	is specified.
     In	addition, these	options	override each other and	the command's actions
     are determined by the last	one specified.

     Only the owner of a file or the super-user	is permitted to	change the
     mode of a file.

EXIT STATUS
     The chmod utility exits 0 on success, and >0 if an	error occurs.

MODES
     Modes may be absolute or symbolic.	 An absolute mode is an	octal number
     constructed from the sum of one or	more of	the following values:

	   4000	   (the	setuid bit).  Executable files with this bit set will
		   run with effective uid set to the uid of the	file owner.
		   Directories with this bit set will force all	files and sub-
		   directories created in them to be owned by the directory
		   owner and not by the	uid of the creating process, if	the
		   underlying file system supports this	feature: see chmod(2)
		   and the suiddir option to mount(8).
	   2000	   (the	setgid bit).  Executable files with this bit set will
		   run with effective gid set to the gid of the	file owner.
	   1000	   (the	sticky bit).  See chmod(2) and sticky(7).
	   0400	   Allow read by owner.
	   0200	   Allow write by owner.
	   0100	   For files, allow execution by owner.	 For directories,
		   allow the owner to search in	the directory.
	   0040	   Allow read by group members.
	   0020	   Allow write by group	members.
	   0010	   For files, allow execution by group members.	 For directo-
		   ries, allow group members to	search in the directory.
	   0004	   Allow read by others.
	   0002	   Allow write by others.
	   0001	   For files, allow execution by others.  For directories
		   allow others	to search in the directory.

     For example, the absolute mode that permits read, write and execute by
     the owner,	read and execute by group members, read	and execute by others,
     and no set-uid or set-gid behaviour is 755	(400+200+100+040+010+004+001).

     The symbolic mode is described by the following grammar:

	   mode		::= clause [, clause ...]
	   clause	::= [who ...] [action ...] action
	   action	::= op [perm ...]
	   who		::= a |	u | g |	o
	   op		::= + |	- | =
	   perm		::= r |	s | t |	w | x |	X | u |	g | o

     The who symbols ``u'', ``g'', and ``o'' specify the user, group, and
     other parts of the	mode bits, respectively.  The who symbol ``a'' is
     equivalent	to ``ugo''.

     The perm symbols represent	the portions of	the mode bits as follows:

	   r	   The read bits.
	   s	   The set-user-ID-on-execution	and set-group-ID-on-execution
		   bits.
	   t	   The sticky bit.
	   w	   The write bits.
	   x	   The execute/search bits.
	   X	   The execute/search bits if the file is a directory or any
		   of the execute/search bits are set in the original (unmodi-
		   fied) mode.	Operations with	the perm symbol	``X'' are only
		   meaningful in conjunction with the op symbol	``+'', and are
		   ignored in all other	cases.
	   u	   The user permission bits in the original mode of the	file.
	   g	   The group permission	bits in	the original mode of the file.
	   o	   The other permission	bits in	the original mode of the file.

     The op symbols represent the operation performed, as follows:

     +	   If no value is supplied for perm, the ``+'' operation has no
	   effect.  If no value	is supplied for	who, each permission bit spec-
	   ified in perm, for which the	corresponding bit in the file mode
	   creation mask (see umask(2))	is clear, is set.  Otherwise, the mode
	   bits	represented by the specified who and perm values are set.

     -	   If no value is supplied for perm, the ``-'' operation has no
	   effect.  If no value	is supplied for	who, each permission bit spec-
	   ified in perm, for which the	corresponding bit in the file mode
	   creation mask is clear, is cleared.	Otherwise, the mode bits rep-
	   resented by the specified who and perm values are cleared.

     =	   The mode bits specified by the who value are	cleared, or, if	no who
	   value is specified, the owner, group	and other mode bits are
	   cleared.  Then, if no value is supplied for who, each permission
	   bit specified in perm, for which the	corresponding bit in the file
	   mode	creation mask is clear,	is set.	 Otherwise, the	mode bits rep-
	   resented by the specified who and perm values are set.

     Each clause specifies one or more operations to be	performed on the mode
     bits, and each operation is applied to the	mode bits in the order speci-
     fied.

     Operations	upon the other permissions only	(specified by the symbol ``o''
     by	itself), in combination	with the perm symbols ``s'' or ``t'', are
     ignored.

     The ``w'' permission on directories will permit file creation, reloca-
     tion, and copy into that directory.  Files	created	within the directory
     itself will inherit its group ID.

EXAMPLES
     644	   make	a file readable	by anyone and writable by the owner
		   only.

     go-w	   deny	write permission to group and others.

     =rw,+X	   set the read	and write permissions to the usual defaults,
		   but retain any execute permissions that are currently set.

     +X		   make	a directory or file searchable/executable by everyone
		   if it is already searchable/executable by anyone.

     755
     u=rwx,go=rx
     u=rwx,go=u-w  make	a file readable/executable by everyone and writable by
		   the owner only.

     go=	   clear all mode bits for group and others.

     g=u-w	   set the group bits equal to the user	bits, but clear	the
		   group write bit.

COMPATIBILITY
     The -v option is non-standard and its use in scripts is not recommended.

SEE ALSO
     chflags(1), install(1), setfacl(1), chmod(2), stat(2), umask(2), fts(3),
     setmode(3), sticky(7), symlink(7),	chown(8), mount(8)

STANDARDS
     The chmod utility is expected to be IEEE Std 1003.2 (``POSIX.2'') compat-
     ible with the exception of	the perm symbol	``t'' which is not included in
     that standard.

HISTORY
     A chmod command appeared in Version 1 AT&T	UNIX.

BUGS
     There is no perm option for the naughty bits of a horse.

FreeBSD	10.1		       January 26, 2009			  FreeBSD 10.1

NAME | SYNOPSIS | DESCRIPTION | EXIT STATUS | MODES | EXAMPLES | COMPATIBILITY | SEE ALSO | STANDARDS | HISTORY | BUGS

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