CHMOD(1) | General Commands Manual | CHMOD(1) |
chmod
— change
file modes
chmod |
[-R [-H |
-L | -P ]]
[-dfh ] mode
file ... |
chmod |
[-R [-H |
-L | -P ]]
[-dfh ] --reference=rfile
file ... |
The chmod
utility modifies the file mode
bits of the listed files as specified by the mode
operand, or copied from a reference rfile, as
specified with the --reference
argument.
The options are as follows:
-H
-R
option is specified, symbolic links on
the command line are followed. (Symbolic links encountered in the tree
traversal are not followed.)-L
-R
option is specified, all symbolic links
are followed.-P
-R
option is specified, no symbolic links
are followed.-R
-d
-f
chmod
fails to change the mode of a
file.-h
The -H
, -L
and
-P
options are ignored unless the
-R
option is specified. In addition, these options
override each other and the command's actions are determined by the last one
specified. The default is as if the -P
option had
been specified.
Only the owner of a file or the super-user is permitted to change the mode of a file.
The chmod
utility exits 0 on
success, and >0 if an error occurs.
Modes may be absolute or symbolic. An absolute mode is an octal number constructed by or'ing the following values:
The read, write, and execute/search values for group and others are encoded as described for owner.
The symbolic mode is described by the following grammar:
mode ::= clause [, clause ...] clause ::= [who ...] [action ...] last_action action ::= op [perm ...] last_action ::= op [perm ...] who ::= a | u | g | o op ::= + | - | = perm ::= r | s | t | w | x | X | u | g | o
The who symbols ``u'', ``g'', and ``o'' specify the user, group, and other parts of the mode bits, respectively. The who symbol ``a'' is equivalent to ``ugo''.
The perm symbols represent the portions of the mode bits as follows:
The op symbols represent the operation performed, as follows:
Each clause specifies one or more operations to be performed on the mode bits, and each operation is applied to the mode bits in the order specified.
Operations upon the other permissions only (specified by the symbol ``o'' by itself), in combination with the perm symbols ``s'' or ``t'', are ignored.
644
go-w
=rw,+X
+X
755
u=rwx,go=rx
u=rwx,go=u-w
go=
g=u-w
chflags(1), install(1), chmod(2), stat(2), umask(2), fts(3), setmode(3), symlink(7), chown(8)
The chmod
utility is expected to be
IEEE Std 1003.2-1992 (“POSIX.2”)
compatible with the exception of the perm symbol
“t” which is not included in that standard.
A chmod
utility appeared in
Version 1 AT&T UNIX.
There's no perm option for the naughty bits.
August 11, 2016 | NetBSD 10.99 |