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chmod(1)							      chmod(1)

       chmod - Changes permission codes

   Absolute Mode
       chmod [-fR] absolute_mode file...

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

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

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

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

       Interfaces documented on this reference page conform to industry	 stan‐
       dards as follows:

       chmod:  XCU5.0

       Refer  to  the  standards(5)  reference page for more information about
       industry standards and associated tags.

       [Tru64 UNIX]  Does not report an error if chmod	fails  to  change  the
       mode  on	 a  file.   Causes  chmod to recursively descend its directory
       arguments, setting the mode for each file as described in the  sections
       Symbolic	 Mode and Absolute Mode.  When symbolic links are encountered,
       their mode is not changed and they are not traversed.

       Pathname of the file that is to	have  the  permission  bits  modified.
       Octal  permission_code  for setting the file permissions.  This code is
       formed as described under Absolute Mode	in  the	 DESCRIPTION  section.
       Specifies  whether  permissions are being defined for a user, group, or
       all others.  This operand is more fully described under	Symbolic  Mode
       in the DESCRIPTION Section.  Specifies the operation to be performed on
       the permissions being defined.  This operand is	more  fully  described
       under  Symbolic Mode in the DESCRIPTION Section.	 Specifies the permis‐
       sions being defined.  This operand is more fully described  under  Sym‐
       bolic Mode in the DESCRIPTION Section.

       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.

       [Tru64  UNIX]  If  a  named  file is a symbolic link, chmod changes the
       mode of the link's target file unless the -R option is used. If the  -R
       option is used, chmod leaves links and their target files untouched.

   Symbolic Mode
       A  symbolic  mode  has  the form: [who] operation permission [operation
       permission] ...

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

       Valid options for the who argument are as follows: User	(owner)	 Group
       All  others User, group, and all others (same effect as the combination

       [Tru64 UNIX]  If the who argument is omitted, the default is a. If  the
       environment  variable  STDS_FLAG is set to ALL, the setting of the file
       creation mask, umask (see umask(1), csh, ksh, sh), is applied.

       Valid options for the operation argument are as follows: Removes speci‐
       fied  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: Read  permis‐
       sion.   Write permission.  Execute permission for files, search permis‐
       sion for directories.  Execute permission only if file is  a  directory
       or  at  least one execute bit is set.  Set-user-ID or set-group-ID per‐

	      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 combination with the u or g
	      option to allow temporary or restricted access to files not nor‐
	      mally accessible to other users.	An s appears in	 the  user  or
	      group  execute  position of a long listing (see ls) to show that
	      the file	runs  with  set-user-ID	 or  set-group-ID  permission.
	      [Tru64 UNIX]  Save text permission.

	      [Tru64  UNIX]  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.  A t appears in the exe‐
	      cute position of the all others option to indicate that the file
	      has this bit (the sticky bit) set.

	      [Tru64  UNIX]  If a directory has this bit set, then deletion in
	      it is restricted.	 An entry in a sticky directory can be removed
	      or  renamed  by a user only if the user has write permission for
	      the directory and the user is the owner of the file,  the	 owner
	      of  the  directory,  or  the superuser.  [Tru64 UNIX]  Mandatory

	      [Tru64 UNIX]  Mandatory file and	record	locking	 refers	 to  a
	      file's  ability  to have read and write permissions locked while
	      another program is accessing that file.  It is not  possible  to
	      permit group execution and enable a file to be locked on an exe‐
	      cution  at the same time.	 In addition, it is  not  possible  to
	      turn  on	the set-group-ID bit and enable a file to be locked on
	      execution at the same time.  In order to turn on a  file's  set-
	      group-ID	bit,  your  own group ID must correspond to the file's
	      and group execution must be set.

       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 commas.	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  per‐
       mission	code.	The  chmod command sets the permissions to the permis‐
       sion_code you provide.  The permission_code is constructed by combining
       (logical	 OR)  the  following  values: Sets user ID on execution.  Sets
       group ID on execution.  [Tru64 UNIX]  Sets the sticky bit,  which  does
       the following: [Tru64 UNIX]  Retains memory image after execution (exe‐
       cutable file) [Tru64 UNIX]  Restricts file removal (directory file)

	      [Tru64 UNIX]  You must have appropriate privileges  to  set  the
	      sticky  bit.   See  chmod(2).   Permits  read by owner.  Permits
	      write by owner.  Permits execute or search  by  owner.   Permits
	      read  by	group.	 Permits  write	 by group.  Permits execute or
	      search by group.	Permits read by others.	 Permits write by oth‐
	      ers.  Permits execute or search by others.

   System V Compatibility
       [Tru64 UNIX]  The root of the directory tree that contains the commands
       modified	 for  SVID   2	 compliance   is   specified   in   the	  file
       /etc/svid2_path. You can use /etc/svid2_profile as the basis for, or to
       include in, your /etc/svid2_profile reads /etc/svid2_path and sets  the
       first  entries  in  the	PATH environment variable so that the modified
       SVID 2 commands are found first.

       [Tru64 UNIX]  The SVID 2 compliant version of the chmod command ignores
       the  umask  value  if  who is not specified in the symbolic mode of the
       command (chmod [who] operation permission).  In	other  words,  if  you
       omit  who  from the chmod command line, the version of the command that
       is compliant with the SVID 2 standard behaves exactly as if you	speci‐
       fied  the  character  a as the value for who.  The version of the chmod
       command that is SVID 2 compliant also supports equivalents in  absolute
       mode  for the s permission in symbolic mode.  In absolute mode, setting
       the bits 04000 represents set-user-ID and setting the bits 02000 repre‐
       sents set-group-ID.

       The  correspondence  between  octal  value and mode bit is given in the
       following table.

       Octal Value   Symbolic Mode   Meaning
       S_ISUID	     4000	     set user id on execution
       S_ISGID	     2000	     set group id on execution
       S_IRUSR	     0400	     read permission: owner
       S_IWUSR	     0200	     write permission: owner
       S_IXUSR	     0100	     execute/search  permission:
       S_IRGRP	     0040	     read permission: group
       S_IWGRP	     0020	     write permission: group
       S_IXGRP	     0010	     execute/search  permission:
       S_IROTH	     0004	     read permission: other
       S_IWOTH	     0002	     write permission: other
       S_IXOTH	     0001	     execute/search  permission:

       The  following  exit  values  are  returned: Successful completion.  An
       error occurred.

       To add a type of permission to several files, enter:  chmod  g+w	 chap1

	      This  adds write permission for group members to the files chap1
	      and chap2.  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 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 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	effec‐
	      tive  IDs	 associated  with  the	subprocess  that  runs cmd are
	      changed.	 The  effective	 IDs  of  the  shell  session	remain

	      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.  Although dbms is
	      not actually a person, it 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 permis‐
	      sion to execute 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	 standard  shell  com‐
	      mands.   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.

       The following environment variables affect the execution of chmod: Pro‐
       vides a default value for the internationalization variables  that  are
       unset  or  null. If LANG is unset or null, the corresponding value from
       the default locale is used. If any of  the  internationalization	 vari‐
       ables contain an invalid setting, the utility behaves as if none of the
       variables had been defined.  If set to a non-empty string value,	 over‐
       rides  the  values  of  all  the	 other internationalization variables.
       Determines the locale for the interpretation of sequences of  bytes  of
       text  data as characters (for example, single-byte as opposed to multi‐
       byte characters in arguments).  Determines the locale  for  the	format
       and  contents of diagnostic messages written to standard error.	Deter‐
       mines the location of message catalogues for the processing of  LC_MES‐
       SAGES.	Resolves  the  behavior	 of the command in some scenarios that
       cause noncompliance with POSIX standards. Setting this variable to  ALL
       enables the command to overcome all instances of noncompliance.

       [Tru64  UNIX]  Defines  the  correspondence  between symbolic codes and
       octal mode values.

       Commands:  chgrp(1), chown(1),  csh(1),	ksh(1),	 ls(1),	 Bourne	 shell
       sh(1b), POSIX shell sh(1p), umask(1)

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

       Standards:  standards(5)


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