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CHMOD(1)                              FSF                             CHMOD(1)

NAME
       chmod - change file access permissions

SYNOPSIS
       chmod [OPTION]... MODE[,MODE]... FILE...
       chmod [OPTION]... OCTAL-MODE FILE...
       chmod [OPTION]... --reference=RFILE FILE...

DESCRIPTION
       This manual page documents the GNU version of chmod.  chmod changes the
       permissions of each given file according to mode, which can be either a
       symbolic representation of changes to make, or an octal number
       representing the bit pattern for the new permissions.

       The format of a symbolic mode is
       `[ugoa...][[+-=][rwxXstugo...]...][,...]'.  Multiple symbolic
       operations can be given, separated by commas.

       A combination of the letters `ugoa' controls which users' access to the
       file will be changed: the user who owns it (u), other users in the
       file's group (g), other users not in the file's group (o), or all users
       (a).  If none of these are given, the effect is as if `a' were given,
       but bits that are set in the umask are not affected.

       The operator `+' causes the permissions selected to be added to the
       existing permissions of each file; `-' causes them to be removed; and
       `=' causes them to be the only permissions that the file has.

       The letters `rwxXstugo' select the new permissions for the affected
       users: read (r), write (w), execute (or access for directories) (x),
       execute only if the file is a directory or already has execute
       permission for some user (X), set user or group ID on execution (s),
       sticky (t), the permissions granted to the user who owns the file (u),
       the permissions granted to other users who are members of the file's
       group (g), and the permissions granted to users that are in neither of
       the two preceding categories (o).

       A numeric mode is from one to four octal digits (0-7), derived by
       adding up the bits with values 4, 2, and 1.  Any omitted digits are
       assumed to be leading zeros.  The first digit selects the set user ID
       (4) and set group ID (2) and sticky (1) attributes.  The second digit
       selects permissions for the user who owns the file: read (4), write
       (2), and execute (1); the third selects permissions for other users in
       the file's group, with the same values; and the fourth for other users
       not in the file's group, with the same values.

       chmod never changes the permissions of symbolic links; the chmod system
       call cannot change their permissions.  This is not a problem since the
       permissions of symbolic links are never used.  However, for each
       symbolic link listed on the command line, chmod changes the permissions
       of the pointed-to file.  In contrast, chmod ignores symbolic links
       encountered during recursive directory traversals.

STICKY FILES
       On older Unix systems, the sticky bit caused executable files to be
       hoarded in swap space.  This feature is not useful on modern VM
       systems, and the Linux kernel ignores the sticky bit on files.  Other
       kernels may use the sticky bit on files for system-defined purposes.
       On some systems, only the superuser can set the sticky bit on files.

STICKY DIRECTORIES
       When the sticky bit is set on a directory, files in that directory may
       be unlinked or renamed only by root or their owner.  Without the sticky
       bit, anyone able to write to the directory can delete or rename files.
       The sticky bit is commonly found on directories, such as /tmp, that are
       world-writable.

OPTIONS
       Change the mode of each FILE to MODE.

       -c, --changes
              like verbose but report only when a change is made

       -f, --silent, --quiet
              suppress most error messages

       -v, --verbose
              output a diagnostic for every file processed

       --reference=RFILE
              use RFILE's mode instead of MODE values

       -R, --recursive
              change files and directories recursively

       --help display this help and exit

       --version
              output version information and exit

       Each MODE is one or more of the letters ugoa, one of the symbols +-=
       and one or more of the letters rwxXstugo.

AUTHOR
       Written by David MacKenzie.

REPORTING BUGS
       Report bugs to <bug-coreutils@gnu.org>.

COPYRIGHT
       Copyright (C) 2002 Free Software Foundation, Inc.
       This is free software; see the source for copying conditions.  There is
       NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
       PURPOSE.

SEE ALSO
       The full documentation for chmod is maintained as a Texinfo manual.  If
       the info and chmod programs are properly installed at your site, the
       command

              info chmod

       should give you access to the complete manual.

chmod (coreutils) 4.5.3          February 2003                        CHMOD(1)

NAME | SYNOPSIS | DESCRIPTION | STICKY FILES | STICKY DIRECTORIES | OPTIONS | AUTHOR | REPORTING BUGS | COPYRIGHT | SEE ALSO

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