NAME
	  chmod	- Changes permission codes

     SYNOPSIS
	  chmod	[-fR] absolute_mode file ...

	  chmod	[-fR] [who] +permission	...  file ...

	  chmod	[-fR] [who] -permission	...  file ...

	  chmod	[-fR] [who] =[permission ...]  file ...


	  The chmod command modifies the read, write, and execute per-
	  missions of specified	files and the search permissions of
	  specified directories.

     FLAGS
	  -f  Does not report an error if chmod	fails to change	the
	      mode on a	file.

	  -R  Causes chmod to recursively descend its directory	argu-
	      ments, setting the mode for each file as described in
	      the sections Symbolic Mode and Absolute Mode.  When sym-
	      bolic links are encountered, their mode is not changed
	      and they are not traversed.


     DESCRIPTION
	  You can use either symbolic or absolute mode to specify the
	  desired permission settings.	You can	change the permission
	  code of a file or directory only if you own it or if you
	  have superuser authority.

	Symbolic Mode
	  A symbolic mode has the form:

	  [who]	operation permission [operation	permission] ...

	  The who argument specifies whether you are defining permis-
	  sions	for a user, group, or all others, or any combination
	  of these.  The operation argument specifies whether the per-
	  mission is being added, taken	away, or assigned absolutely.
	  The permission argument identifies the operation that	the
	  specified users can perform on file.

	  Valid	options	for the	who argument are as follows:


	  u   User (owner)

	  g   Group
	  o   All others

	  a   User, group, and all others (same	effect as the combina-
	      tion ugo)


	  If the who argument is omitted, the default is a, but	the
	  setting of the file creation mask, umask (see	csh, ksh, sh),
	  is applied.

	  Valid	options	for the	operation argument are as follows:


	  -   Removes specified	permissions.

	  +   Adds specified permissions.

	  =   Clears the selected permission field and sets it to the
	      code specified.  If you do not specify a permission code
	      following	=, chmod removes all permissions from the
	      selected field.


	  Valid	options	for the	permission argument are	as follows:


	  r   Read permission.

	  w   Write permission.

	  x   Execute permission for files, search permission for
	      directories.

	  X   Execute permission only if file is a directory or	at
	      least one	execute	bit is set.

	  s   Set-user-ID or set-group-ID permission.

	      This permission bit sets the effective user ID or	group
	      ID to that of the	owner or group owner of	file whenever
	      the file is run.	Use this permission setting in combi-
	      nation with the u	or g option to allow temporary or res-
	      tricted access to	files not normally accessible to other
	      users.  An s appears in the user or group	execute	posi-
	      tion of a	long listing (see ls) to show that the file
	      runs with	set-user-ID or set-group-ID permission.

	  t   Save text	permission.

	      In earlier versions of the UNIX system, setting this
	      permission bit caused the	text segment of	a program to
	      remain in	virtual	memory after its first use.  The
	      system thus avoided having to transfer the program code
	      of frequently accessed programs into the paging area.
	      You can specify this permission, but in OSF/1 it has no
	      effect.  A t appears in the execute position of the all
	      others option to indicate	that the file has this bit
	      (the sticky bit) set.

	      If a directory has this bit set, then deletion in	it is
	      restricted.  An entry in a sticky	directory can only be
	      removed or renamed by a user if the user has write per-
	      mission for the directory	and the	user is	the owner of
	      the file,	the owner of the directory, or the superuser.


	  The u, g, and	o options indicate that	permission is to be
	  taken	from the current mode.	Omitting permission is only
	  useful with =	to take	away all permissions.

	  All permission bits not explicitly specified are cleared.

	  You can specify multiple symbolic modes, separated with com-
	  mas.	Do not separate	items in this list with	spaces.
	  Operations are performed in the order	they appear from left
	  to right.

	Absolute Mode
	  Absolute mode	lets you use octal notation to set each	bit in
	  the permission code.	The chmod command sets the permissions
	  to the permission_code you provide.  permission_code is con-
	  structed by combining	(the logical OR	of) the	following
	  values:


	  4000
	      Sets user	ID on execution.

	  2000
	      Sets group ID on execution.

	  1000
	      Sets sticky bit (see chmod(2)):


		o  Retains memory image	after execution	(executable
		   file).  Has no effect in OSF/1.

		o  Restricts file removal (directory).


	  0400
	      Permits read by owner.

	  0200
	      Permits write by owner.

	  0100
	      Permits execute or search	by owner.

	  0040
	      Permits read by group.

	  0020
	      Permits write by group.

	  0010
	      Permits execute or search	by group.

	  0004
	      Permits read by others.

	  0002
	      Permits write by others.

	  0001
	      Permits execute or search	by others.


     EXAMPLES
	   1.  To add a	type of	permission to several files, enter:

	       chmod  g+w  chap1 chap2



	       This adds write permission for group members to the
	       files chap1 and chap2.

	   2.  To make several permission changes at once, enter:

	       chmod  go-w+x  mydir



	       This denies group members and others the	permission to
	       create or delete	files in mydir (go-w).	It allows them
	       to search mydir or use it in a pathname (go+x).	This
	       is equivalent to	the following command sequence:

	       chmod  g-w  mydir
	       chmod  o-w  mydir
	       chmod  g+x  mydir
	       chmod  o+x  mydir


	   3.  To permit only the owner	to use a shell procedure as a
	       command,	enter:

	       chmod  u=rwx,go=	 cmd



	       This gives read,	write, and execute permission to the
	       user who	owns the file (u=rwx).	It also	denies the
	       group and others	the permission to access cmd in	any
	       way (go=).

	       If you have permission to execute the cmd shell command
	       file, you can run it by entering:

	       cmd



	       or

	       ./cmd



	   4.  To use set-ID modes, enter:

	       chmod  ug+s  cmd



	       When cmd	is executed, this causes the effective user
	       and group IDs to	be set to those	that own the file cmd.
	       Only the	effective IDs associated with the subprocess
	       that runs cmd are changed.  The effective IDs of	the
	       shell session remain unchanged.

	       This feature allows you to permit restricted access to
	       important files.	 Suppose that the file cmd has the
	       set-user-ID mode	enabled	and is owned by	a user called
	       dbms.  dbms is not actually a person, but might be
	       associated with a database management system.  The user
	       betty does not have permission to access	any of dbms's
	       data files.  However, she does have permission to exe-
	       cute cmd.  When she does	so, her	effective user ID is
	       temporarily changed to dbms, so that the	cmd program
	       can access the data files owned by dbms.

	       This way	betty can use cmd to access the	data files,
	       but she cannot accidentally damage them with the	stan-
	       dard shell commands.

	   5.  To use the absolute mode	form of	the chmod command,
	       enter:

	       chmod  644  text



	       This sets read and write	permission for the owner, and
	       it sets read-only mode for the group and	all others.


     RELATED INFORMATION
	  Commands:  chgrp(1), chown(1), csh(1), ksh(1), ls(1),	sh(1).

	  Functions:  chown(2),	chmod(2), stat(2), umask(2).