CHMOD(1) BSD Reference Manual CHMOD(1)
c
\bch
\bhm
\bmo
\bod
\bd - change file modes
S
\bSY
\bYN
\bNO
\bOP
\bPS
\bSI
\bIS
\bS
c
\bch
\bhm
\bmo
\bod
\bd [-
\b-R
\bR [-
\b-H
\bH | -
\b-L
\bL | -
\b-P
\bP]] _
\bm_
\bo_
\bd_
\be _
\bf_
\bi_
\bl_
\be _
\b._
\b._
\b.
D
\bDE
\bES
\bSC
\bCR
\bRI
\bIP
\bPT
\bTI
\bIO
\bON
\bN
The c
\bch
\bhm
\bmo
\bod
\bd utility modifies the file mode bits of the listed files as
specified by the _
\bm_
\bo_
\bd_
\be operand.
The options are as follows:
-
\b-H
\bH If the -
\b-R
\bR option is specified, symbolic links on the command line
are followed. (Symbolic links encountered in the tree traversal
-
\b-L
\bL If the -
\b-R
\bR option is specified, all symbolic links are followed.
-
\b-P
\bP If the -
\b-R
\bR option is specified, no symbolic links are followed.
-
\b-R
\bR Change the modes of the file hierarchies rooted in the files in-
stead of just the files themselves.
Symbolic links do not have modes, so unless the -
\b-H
\bH or -
\b-L
\bL option is set,
c
\bch
\bhm
\bmo
\bod
\bd on a symbolic link always succeeds and has no effect. The -
\b-H
\bH, -
\b-L
\bL
and -
\b-P
\bP options are ignored unless the -
\b-R
\bR option is specified. In addi-
tion, these options override each other and the command's actions are de-
termined by the last one specified.
Only the owner of a file or the super-user is permitted to change the
The c
\bch
\bhm
\bmo
\bod
\bd 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 _
\bo_
\br_
\b-_
\bi_
\bn_
\bg the following values:
4000 set-user-ID-on-execution
2000 set-group-ID-on-execution
1000 sticky bit, see chmod(2)
0100 execute (or search for directories) by owner
0070 read, write, execute/search by group
0007 read, write, execute/search by others
The read, write, and execute/search values for group and others are en-
coded as described for owner.
The symbolic mode is described by the following grammar:
mode ::= clause [, clause ...]
clause ::= [who ...] [action ...] last_action
last_action ::= op [perm ...]
perm ::= r | s | t | w | x | X | u | g | o
The _
\bw_
\bh_
\bo symbols ``u'', ``g'', and ``o'' specify the user, group, and oth-
er parts of the mode bits, respectively. The _
\bw_
\bh_
\bo symbol ``a'' is equiva-
The _
\bp_
\be_
\br_
\bm symbols represent the portions of the mode bits as follows:
s The set-user-ID-on-execution and set-group-ID-on-execution
x The execute/search bits.
X The execute/search bits if the file is a directory or any
of the execute/search bits are set in the original (unmodi-
fied) mode. Operations with the _
\bp_
\be_
\br_
\bm symbol ``X'' are only
meaningful in conjunction with the _
\bo_
\bp symbol ``+'', and are
ignored in all other cases.
u The user permission bits in the mode of the original file.
g The group permission bits in the mode of the original file.
o The other permission bits in the mode of the original file.
The _
\bo_
\bp symbols represent the operation performed, as follows:
+ If no value is supplied for _
\bp_
\be_
\br_
\bm, the ``+'' operation has no ef-
fect. If no value is supplied for _
\bw_
\bh_
\bo, each permission bit speci-
fied in _
\bp_
\be_
\br_
\bm, for which the corresponding bit in the file mode cre-
ation mask is clear, is set. Otherwise, the mode bits represented
by the specified _
\bw_
\bh_
\bo and _
\bp_
\be_
\br_
\bm values are set.
- If no value is supplied for _
\bp_
\be_
\br_
\bm, the ``-'' operation has no ef-
fect. If no value is supplied for _
\bw_
\bh_
\bo, each permission bit speci-
fied in _
\bp_
\be_
\br_
\bm, for which the corresponding bit in the file mode cre-
ation mask is clear, is cleared. Otherwise, the mode bits repre-
sented by the specified _
\bw_
\bh_
\bo and _
\bp_
\be_
\br_
\bm values are cleared.
= The mode bits specified by the _
\bw_
\bh_
\bo value are cleared, or, if no who
value is specified, the owner, group and other mode bits are
cleared. Then, if no value is supplied for _
\bw_
\bh_
\bo, each permission
bit specified in _
\bp_
\be_
\br_
\bm, for which the corresponding bit in the file
mode creation mask is clear, is set. Otherwise, the mode bits rep-
resented by the specified _
\bw_
\bh_
\bo and _
\bp_
\be_
\br_
\bm values are set.
Each _
\bc_
\bl_
\ba_
\bu_
\bs_
\be specifies one or more operations to be performed on the mode
bits, and each operation is applied to the mode bits in the order speci-
Operations upon the other permissions only (specified by the symbol ``o''
by itself), in combination with the _
\bp_
\be_
\br_
\bm symbols ``s'' or ``t'', are ig-
E
\bEX
\bXA
\bAM
\bMP
\bPL
\bLE
\bES
\bS
644 make a file readable by anyone and writable by the owner
go-w deny write permission to group and others.
=rw,+X set the read and write permissions to the usual defaults,
but retain any execute permissions that are currently set.
+X make a directory or file searchable/executable by everyone
if it is already searchable/executable by anyone.
u=rwx,go=u-w make a file readable/executable by everyone and writable by
go= clear all mode bits for group and others.
g=u-w set the group bits equal to the user bits, but clear the
There's no _
\bp_
\be_
\br_
\bm option for the naughty bits.
S
\bSE
\bEE
\bE A
\bAL
\bLS
\bSO
\bO
install(1), chmod(2), stat(2), umask(2), fts(3), setmode(3),
S
\bST
\bTA
\bAN
\bND
\bDA
\bAR
\bRD
\bDS
\bS
The c
\bch
\bhm
\bmo
\bod
\bd utility is expected to be POSIX 1003.2 compatible with the ex-
ception of the _
\bp_
\be_
\br_
\bm symbols ``t'' and ``X'' which are not included in
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