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

NAME
     chmod -- change file modes

SYNOPSIS
     chmod [-fv	-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:

     -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.)

     -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.

     -f	     Do	not display a diagnostic message if chmod could	not modify the
	     mode for file.

     -v	     Cause chmod to be verbose,	showing	files as the mode is modified.

     Symbolic links do not have	modes, so unless the -H	or -L option is	set,
     chmod on a	symbolic link always succeeds and has no effect.  The -H, -L
     and -P options are	ignored	unless the -R option is	specified.  In addi-
     tion, 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.

DIAGNOSTICS
     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	set-user-ID-on-execution bit) Executable files with
		   this	bit set	will run with effective	uid set	to the uid of
		   the file owner.  Directories	with the set-user-id 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	set-group-ID-on-execution bit)	Executable files with
		   this	bit set	will run with effective	gid set	to the gid of
		   the file owner.
	   1000	   (the	sticky bit) When set on	a directory, unprivileged
		   users can delete and	rename only those files	in the direc-
		   tory	that are owned by them,	regardless of the permissions
		   on the directory.  Under FreeBSD, the sticky	bit is ignored
		   for executable files	and may	only be	set for	directories
		   (see	sticky(8)).
	   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 mode	of the original	file.
	   g	   The group permission	bits in	the mode of the	original file.
	   o	   The other permission	bits in	the mode of the	original 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 is clear, is set.  Otherwise, the mode	bits repre-
	   sented 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.

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.

BUGS
     There's no	perm option for	the naughty bits.

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

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

FreeBSD	9.2			March 31, 1994			   FreeBSD 9.2

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

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