chmod

 

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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...][[+-=][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 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 © 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.
 
 
 
 chmod (fileutils) 4.1       April 2001                   CHMOD(1)

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