SysIII/usr/src/man/man1/chmod.1

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.TH CHMOD 1
.SH NAME
chmod \- change mode
.SH SYNOPSIS
.B chmod
mode file ...
.SH DESCRIPTION
The permissions of
each named file
are changed
according to
.IR mode ,
which may be absolute or symbolic.
An absolute
.I mode\^
is an octal
number constructed
from the \s-1OR\s0 of the
following modes:
.PP
.PD 0
.RS
.TP 10
4000
set user
.SM ID
on execution
.TP 10
2000
set group
.SM ID
on execution
.TP 10
1000
sticky bit, see
.IR  chmod (2)
.TP 10
0400
read by owner
.TP 10
0200
write by owner
.TP 10
0100
execute (search in directory) by owner
.TP 10
0070
read, write, execute (search) by group
.TP 10
0007
read, write, execute (search) by others
.RE
.PD
.PP
A symbolic
.I mode\^
has the form:
.IP
.RI [ who ] " op permission " [ " op permission " ]
]
.PP
The
.I who\^
part is a combination
of the letters 
.B u
(for user's permissions),
.B g
(group)
and
.B o
(other).
The letter
.B a
stands for
.BR ugo ,
the default if
.I who\^
is omitted.
.PP
.I Op\^
can be
.B +
to add
.I permission\^
to the file's mode,
.B \-
to take away
.IR permission ,
or
.B =
to assign
.I permission\^
absolutely
(all other bits will
be reset).
.PP
.I Permission\^
is any combination of the letters
.B r
(read),
.B w
(write),
.B x
(execute),
.B s
(set owner or group \s-1ID\s0)
and
.B t
(save text \- sticky);
.BR u ,
.B g
or
.B o
indicate that
.I permission\^
is to be taken
from the current
mode.
Omitting
.I permission\^
is only useful
with
.B =
to take away
all permissions.
.PP
Multiple symbolic modes separated by commas may be given.
Operations are performed
in the order specified.
The letter
.B s
is only useful
with
.B u
or
.B g
and
.B t
only works
with
.BR u .
.PP
Only the owner of a file (or the super-user) may change its mode.
.SH EXAMPLES
The first example denies write permission to others,
the second makes a file executable:
.IP
chmod o\-w file
.br
.sp
chmod +x file
.PP
.SH "SEE ALSO"
ls(1),
chmod(2).