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chmod



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...][[+-=][rwxXs­
       tugo...]...][,...]'.  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 direc­
       tory 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
       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 © 2003 Free Software Foundation, Inc.
       This is free software; see the source for  copying  condi­
       tions.  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  Tex­
       info  manual.  If the info and chmod programs are properly
       installed at your site, the command

              info chmod

  




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