


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...][[+-=][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), save program text
       on swap device (t), the permissions that the user who owns
       the  file  currently  has for it (u), the permissions that
       other users in the file's group have for it (g),  and  the
       permissions  that other users not in the file's group have
       for it (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 save text image (1) attributes.  The second  digit
       selects  permissions  for the user who owns the file: read
       (4), write (2), and execute (1); the third selects permis-
       sions  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 (fileutils) 4.1       April 2002                          1





CHMOD(1)                       FSF                       CHMOD(1)


       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.

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-fileutils@gnu.org>.

COPYRIGHT
       Copyright (C) 2001 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

       should give you access to the complete manual.




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