CHMOD(1) FSF CHMOD(1)NAMEchmod - change file access permissions
SYNOPSISchmod [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)
