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 chmod(1)                                                           chmod(1)




 NAME
      chmod - change file mode access permissions

 SYNOPSIS
      /usr/bin/chmod [-A] [-R] symbolic_mode_list file ...

    Obsolescent form:
      /usr/bin/chmod [-A] [-R] numeric_mode file ...

 DESCRIPTION
      The chmod command changes the permissions of one or more files
      according to the value of symbolic_mode_list or numeric_mode.  You can
      display the current permissions for a file with the ls -l command (see
      ls(1)).

    Symbolic Mode List
      A symbolic_mode_list is a comma-separated list of operations in the
      following form.  Whitespace is not permitted.

           [who]op[permission][,...]

      The variable fields can have the following values:

           who         One or more of the following letters:

                            u    Modify permissions for user (owner).
                            g    Modify permissions for group.
                            o    Modify permissions for others.
                            a    Modify permissions for all users (a is
                                 equivalent to ugo).

           op          Required; one of the following symbols:

                            +    Add permission to the existing file mode
                                 bits of who.
                            -    Delete permission from the existing file
                                 mode bits of who.
                            =    Replace the existing mode bits of who with
                                 permission.

           permission  One or more of the following letters:

                            r    Add or delete the read permission for who.
                            w    Add or delete the write permission for who.
                            x    Add or delete the execute file (search
                                 directory) permission for who.
                            s    Add or delete the set-owner-ID-on-file-
                                 execution or set-group-ID-on-file-execution
                                 permission for who.  Useful only if u or g
                                 is expressed or implied in who.




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 chmod(1)                                                           chmod(1)




                            t    Add or delete the save-text-image-on-file-
                                 execution (sticky bit) permission.  Useful
                                 only if u is expressed or implied in who.
                                 See chmod(2).
                            X    Conditionally add or delete the
                                 execute/search permission as follows:
                                 +  If file is a directory, add or delete
                                    the search permission to the existing
                                    file mode for who.  (Same as x.)
                                 +  If file is not a directory, and the
                                    current file permissions include the
                                    execute permission (ls -l displays an x
                                    or an s) for at least one of user,
                                    group, or other, then add or delete the
                                    execute file permission for who.
                                 +  If file is not a directory, and no
                                    execute permissions are set in the
                                    current file mode, then do not change
                                    any execute permission.

                       Or one only of the following letters:

                            u    Copy the current user permissions to who.
                            g    Copy the current group permissions to who.
                            o    Copy the current other permissions to who.

      The operations are performed in the order specified, and can override
      preceding operations specified in the same command line.

      If who is omitted, the r, w, x, and X permissions are changed for all
      users if the changes are permitted by the current file mode creation
      mask (see umask(1)).  The s and t permissions are changed as if a was
      specified in who.

      Omitting permission is useful only when used with = to delete all
      permissions.

    Numeric Mode (Obsolescent)
      Absolute permissions can be set by specifying a numeric_mode, an octal
      number constructed from the logical OR (sum) of the following mode
      bits:

      Miscellaneous mode bits:

           4000  (= u=s)  Set user ID on file execution (file only)
           2000  (= g=s)  Set group ID on file execution (file only)
           1000  (= u=t)  Set sticky bit; see below and chmod(2)

      Permission mode bits:





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 chmod(1)                                                           chmod(1)




           0400  (= u=r)  Read by owner
           0200  (= u=w)  Write by owner
           0100  (= u=x)  Execute (search in directory) by owner
           0040  (= g=r)  Read by group
           0020  (= g=w)  Write by group
           0010  (= g=x)  Execute/search by group
           0004  (= o=r)  Read by others
           0002  (= o=w)  Write by others
           0001  (= o=x)  Execute/search by others

    Options
           -A   Preserve any optional access control list (ACL) entries
                associated with the file (HFS file systems only).  By
                default, in conformance with the IEEE Standard POSIX
                1003.1-1988, optional HFS ACL entries are deleted.  For JFS
                ACLs, this option has no effect, because optional JFS ACL
                entries are always preserved.  For information about access
                control lists, see acl(5) and aclv(5).

           -R   Recursively change the file mode bits.  For each file
                operand that names a directory, chmod alters the file mode
                bits of the named directory and all files and subdirectories
                in the file hierarchy below it.

      Only the owner of a file, or a user with appropriate privileges, can
      change its mode.

      Only a user having appropriate privileges can set (or retain, if
      previously set) the sticky bit of a regular file.

      If the sticky bit is set on a directory, files inside the directory
      may be renamed or removed only by the owner of the file, the owner of
      the directory, or the superuser (even if the modes of the directory
      would otherwise allow such an operation).

      In order to set the set-group-ID bit, the group of the file must
      correspond to your current group ID.

      If chmod is used on a symbolic link, the mode of the file referred to
      by the link is changed.

 EXTERNAL INFLUENCES
    Environment Variables
      LC_MESSAGES determines the language in which messages are displayed.

      If LC_MESSAGES is not specified or is null, it defaults to the value
      of LANG.  If LANG is not specified or is null, it defaults to C (see
      lang(5)).

      If any internationalization variable contains an invalid setting, all
      internationalization variables default to C.  See environ(5).



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 chmod(1)                                                           chmod(1)




    International Code Set Support
      Single- and multibyte character code sets are supported.

 RETURN VALUE
      Upon completion, chmod returns one of the following values:

            0   Successful completion.
           >&gt&gt>0   An error condition occurred.

 EXAMPLES
      Deny write permission to others:

           chmod o-w file

      Make a file executable by everybody:

           chmod a+x file

      Assign read and execute permission to everybody, and set the set-
      user-ID bit:

           chmod a=rx,u+s file

      Assign read and write permission to the file owner, and read
      permission to everybody else:

           chmod u=rw,go=r file

      or the obsolescent form:

           chmod 644 file

      Traverse a directory subtree making all regular files readable by user
      and group only, and all executables and directories executable
      (searchable) by everyone:

           chmod -R ug+r,o-r,a+X pathname

      If the current value of umask is 020 (umask -S displays
      u=rwx,g=rx,o=rwx; do not change write permission for group) and the
      current permissions for file mytest are 444 (a=r), displayed by ls -l
      as -r--r--r--, then the command

           chmod +w mytest

      sets the permissions to 646 (uo=rw,g=r), displayed by ls -l as
      -rw-r--rw-.

      If the current value of umask is 020 (umask -S displays
      u=rwx,g=rx,o=rwx; do not change write permission for group) and the
      current permissions for file mytest are 666 (a=rw), displayed by ls -l



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 chmod(1)                                                           chmod(1)




      as -rw-rw-rw-, then the command

           chmod -w mytest

      sets the permissions to 464 (uo=r,g=rw), displayed by ls -l as
      -r--rw-r--.

 DEPENDENCIES
      The -A option causes chmod to fail on file systems that do not support
      ACLs.

 AUTHOR
      chmod was developed by AT&T and HP.

 SEE ALSO
      chacl(1), ls(1), umask(1), chmod(2), acl(5), aclv(5).

 STANDARDS CONFORMANCE
      chmod: SVID2, SVID3, XPG2, XPG3, XPG4, POSIX.2



































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