CHMOD(1) User Commands CHMOD(1)

NAME

chmod - change the permissions mode of a file

SYNOPSIS

chmod [-fR] absolute-mode file ...


chmod [-fR] symbolic-mode-list file ...


chmod [-fR] acl_operation file ...


chmod [-fR] [-@ named_attribute]...attribute_specification_list file ...

DESCRIPTION

The chmod utility changes or assigns the mode of a file.


chmod can also be used to modify Access Control Lists (ACLs) on files
and directories, and to modify boolean read-write system attributes
on regular files, directories, and opaque extended attribute files.

Absolute Mode

An absolute mode command line has the following format:


chmod [options] absolute-mode file ...


where absolute-mode is specified using octal numbers nnnn defined as
follows:

n
a number from 0 to 7. An absolute mode is constructed from the
OR of any of the following modes:

4000
Set user ID on execution.


20#0
Set group ID on execution if # is 7, 5, 3, or 1.

Enable mandatory locking if # is 6, 4, 2, or 0.

For directories, files are created with BSD
semantics for propagation of the group ID. With this
option, files and subdirectories created in the
directory inherit the group ID of the directory,
rather than of the current process. For directories,
the set-gid bit can only be set or cleared by using
symbolic mode.


1000
Turn on sticky bit. See chmod(2).


0400
Allow read by owner.


0200
Allow write by owner.


0100
Allow execute (search in directory) by owner.


0700
Allow read, write, and execute (search) by owner.


0040
Allow read by group.


0020
Allow write by group.


0010
Allow execute (search in directory) by group.


0070
Allow read, write, and execute (search) by group.


0004
Allow read by others.


0002
Allow write by others.


0001
Allow execute (search in directory) by others.


0007
Allow read, write, and execute (search) by others.


For directories, the setgid bit cannot be set (or cleared) in
absolute mode; it must be set (or cleared) in symbolic mode using g+s
(or g-s).

Symbolic Mode

A symbolic mode command line has the following format:


chmod [options] symbolic-mode-list file ...


where symbolic-mode-list is a comma-separated list (with no
intervening white space) of symbolic mode expressions of the form:


[who] operator [permissions]


Operations are performed in the order given. Multiple permissions
letters following a single operator cause the corresponding
operations to be performed simultaneously.

who
zero or more of the characters u, g, o, and a
specifying whose permissions are to be changed or
assigned:

u
user's permissions


g
group's permissions


o
others' permissions


a
all permissions (user, group, and other)

If who is omitted, it defaults to a, but the setting of
the file mode creation mask (see umask in sh(1) or
csh(1) for more information) is taken into account.
When who is omitted, chmod does not override the
restrictions of your user mask.


operator
either +, -, or =, signifying how permissions are to be
changed:

+
Add permissions.

If permissions are omitted, nothing is added.

If who is omitted, add the file mode bits
represented by permissions, except for the
those with corresponding bits in the file mode
creation mask.

If who is present, add the file mode bits
represented by the permissions.


-
Take away permissions.

If permissions are omitted, do nothing.

If who is omitted, clear the file mode bits
represented by permissions, except for those
with corresponding bits in the file mode
creation mask.

If who is present, clear the file mode bits
represented by permissions.


=
Assign permissions absolutely.

If who is omitted, clear all file mode bits; if
who is present, clear the file mode bits
represented by who.

If permissions are omitted, do nothing else.

If who is omitted, add the file mode bits
represented by permissions, except for the
those with corresponding bits in the file mode
creation mask.

If who is present, add the file mode bits
represented by permissions.

Unlike other symbolic operations, = has an absolute
effect in that it resets all other bits represented by
who. Omitting permissions is useful only with = to take
away all permissions.


permission
any compatible combination of the following letters:

l
mandatory locking


r
read permission


s
user or group set-ID


t
sticky bit


w
write permission


x
execute permission


X
execute permission if the file is a directory
or if there is execute permission for one of
the other user classes


u,g,o
indicate that permission is to be taken from
the current user, group or other mode
respectively.

Permissions to a file can vary depending on your user
identification number (UID) or group identification
number (GID). Permissions are described in three
sequences each having three characters:


User Group Other
rwx rwx rwx

This example (user, group, and others all have
permission to read, write, and execute a given file)
demonstrates two categories for granting permissions:
the access class and the permissions themselves.

The letter s is only meaningful with u or g, and t only
works with u.

Mandatory file and record locking (l) refers to a
file's ability to have its reading or writing
permissions locked while a program is accessing that
file.

In a directory which has the set-group-ID bit set
(reflected as either -----s--- or -----l--- in the
output of 'ls -ld'), files and subdirectories are
created with the group-ID of the parent directory--not
that of current process.

It is not possible to permit group execution and enable
a file to be locked on execution at the same time. In
addition, it is not possible to turn on the set-group-
ID bit and enable a file to be locked on execution at
the same time. The following examples, therefore, are
invalid and elicit error messages:

chmod g+x,+l file
chmod g+s,+l file


Only the owner of a file or directory (or the super-
user) can change that file's or directory's mode. Only
the super-user can set the sticky bit on a non-
directory file. If you are not super-user, chmod masks
the sticky-bit but does not return an error. In order
to turn on a file's set-group-ID bit, your own group ID
must correspond to the file's and group execution must
be set.

ACL Operation

An ACL Operation command line has the following format:

chmod [options] A[number]- file ...
chmod [options] A-acl_specification file ...
chmod [options] A[index]{+|=}acl_specification file ...


Where acl_specification is a comma-separated list (with no
intervening white space) of an ACL specification of the form:

A[index]+acl_specification
Prepends the access control entries
(ACE) specified in acl_specification to
the beginning of the file's ACL.
Depending on the file system, the ACL
can be reordered when applied to the
file. If "optional" number is specified
then new ACEs are inserted before
specified number.


A-
Removes all ACEs for current ACL on
file and replaces current ACL with new
ACL that represents only the current
mode of the file.


Aindex-
Removes ACE specified by index number.


A-acl_specification
Removes ACEs specified by
acl_specification, if they exist in
current file's ACL.


A=acl_specification
Replaces a files entire ACL with
acl_specification.


A[index]=acl_specification
Replaces ACEs starting at a specific
index number in the current ACL on the
file. If multiple ACEs are specified,
then each subsequent ACE in
acl_specification replaces the
corresponding ACE in the current ACL.


POSIX-draft ACL Specification (as supported by UFS)


POSIX-draft ACLs (as supported by UFS) are specified as colon (:)
separated fields of the following.

user::perms

File owner permissions.


user:username:perms

Permissions for a specific user.


group::perms

File group owner permissions.


group:groupname:perms

Permissions for a specific group.


other::perms

Permissions for user other than the file owner or members of file
group owner.


mask:perms

The ACL mask. The mask entry specifies the maximum permissions
allowed for user (other than that the owner) and for groups.


default:user::perms

Default file owner permissions.


default:user:username:perms

Default permissions for a specific user.


default:group::perms

Default file group owner permissions.


default:group:groupname:perms

Default permissions for a specific group.


default:other:perms

Default permissions for user other than the file owner or members
of the file group owner.


default:mask:perms

Default ACL mask.


The above specification allows for ACLs to be specified such as:

user:tom:rw-,mask:rwx,group:staff:r-x


NFSv4 ACL Specification (as supported by NFSv4 and ZFS)


NFSv4 ACLs provide richer ACL semantics. They provide both allow and
deny entries, finer grained permissions, and enhanced inheritance
control.


NFSv4 ACLs are specified as colon (:) separated fields of the
following.

owner@:<perms>[:inheritance flags]:<allow|deny>

Permissions for file owner.


group@:<perms>[:inheritance flags]:<allow|deny>

Permissions for file group owner.


everyone@:<perms>[:inheritance flags]:<allow|deny>

Permissions for everyone, including file owner and group owner.


user:<username>:<perms>[:inheritance flags]:<allow|deny>

Permissions for a specific user.


usersid:<sid string>:<perms>[:inheritance flags]:<allow|deny>

Permissions for a specific user, but user is specified by SID.


group:<groupname>:<perms>[:inheritance flags]:<allow|deny>

Permissions for a specific group.


groupsid:<sid string>:<perms>[:inheritance flags]:<allow|deny>

Permissions for a specific group, but group is specified by SID.


sid:<sid string>:<perms>[:inheritance flags]:<allow|deny>

Permissions for a specific SID, but it doesn't matter if it is a
user or a group.


Permissions can be specified in three different chmod ACL formats:
verbose, compact, or positional. The verbose format uses words to
indicate that the permissions are separated with a forward slash (/)
character. Compact format uses the permission letters and positional
format uses the permission letters or the hyphen (-) to identify no
permissions.


The permissions for verbose mode and their abbreviated form in
parentheses for compact and positional mode are described as follows:

read_data (r)
Permission to read the data of a file.


list_directory (r)
Permission to list the contents of a
directory.


write_data (w)
Permission to modify a file's data. anywhere
in the file's offset range.


add_file (w)
Permission to add a new file to a directory.


append_data (p)
The ability to modify a file's data, but only
starting at EOF.

Currently, this permission is not supported.


add_subdirectory (p)
Permission to create a subdirectory to a
directory.


read_xattr (R)
Ability to read the extended attributes of a
file.


write_xattr (W)
Ability to create extended attributes or
write to the extended attribute directory.


execute (x)
Permission to execute a file.


read_attributes (a)
The ability to read basic attributes (non-
ACLs) of a file.


write_attributes (A)
Permission to change the times associated
with a file or directory to an arbitrary
value.


delete (d)
Permission to delete a file.


delete_child (D)
Permission to delete a file within a
directory.


read_acl (c)
Permission to read the ACL of a file.


write_acl (C)
Permission to write the ACL of a file.


write_owner (o)
Permission to change the owner of a file.


synchronize (s)
Permission to access file locally at server
with synchronize reads and writes.

Currently, this permission is not supported.


Using the compact ACL format, permissions are specified by using 14
unique letters to indicate permissions.


Using the positional ACL format, permissions are specified as
positional arguments similar to the ls -V format. The hyphen (-),
which indicates that no permission is granted at that position, can
be omitted and only the required letters have to be specified.


The letters above are listed in the order they would be specified in
positional notation.


Permissions can be specified with these letters in the following way:

rwx--D--------


The hyphens can be removed to compact the string as follows:

rwxD


Several special permission sets or aliases are also supported. The
following permission sets are used the same way that verbose
permissions are specified.

full_set
All permissions.


modify_set
All permissions except write_acl and write_owner.


read_set
read_data, read_acl, read_attributes, and read_xattr.


write_set
write_data, append_data, write_attributes, and
write_xattr


The optional inheritance flags can be specified in the three formats.
The first format uses words to indicate the various inheritance flags
separated with a forward slash (/) character.

file_inherit (f)
Inherit to all newly created files.


dir_inherit (d)
Inherit to all newly created directories.


inherit_only (i)
When placed on a directory, do not apply to the
directory, only to newly created files and
directories. This flag requires that either
file_inherit and or dir_inherit is also
specified.


no_propagate (n)
Indicates that ACL entries should be inherited to
objects in a directory, but inheritance should
stop after descending one level. This flag is
dependent upon either file_inherit and or
dir_inherit also being specified.


successful_access (S)
Indicates whether an alarm or audit record should
be initiated upon successful accesses. Used with
audit/alarm ACE types.


failed_access (F)
Indicates whether an alarm or audit record should
be initiated when access fails. Used with
audit/alarm ACE types.


inherited (I)
ACE was inherited.


The inheritance flags listed can also be specified in the compact
format or as positional arguments similar to the ls -V format. A
hyphen character indicates that the inheritance flag at that position
is not specified in the positional ACL format.


The inheritance flags can be specified with these letters in any of
the following equivalent ways.

file_inherit/dir_inherit/no_propagate


fd-n---


fdn


With this inheritance model, an ACL entry can be specified such as:

user:tom:read_data/write_data/read_attributes:file_inherit:allow
user:fred:read_data:file_inherit/dir_inherit:deny
user:bob:read_data:allow

Attribute Operation

An attribute operation command line has the following format:

chmod [options] attribute_specification_list file ...


where attribute_specification_list is the character S followed by a
comma-separated list of one or more attribute_specifications. Each
attribute_specification is of the form:

[operator]attribute_specifier


An operator is one of the following:

+
Each attribute specified by the associated attribute_specifier
is adjusted to match the value specified by the
attribute_specifier.


-
Each attribute specified by the associated attribute_specifier
is adjusted to match the inverse of the value specified by the
attribute_specifier.


=
Each attribute specified by the associated attribute_specifier
is adjusted to match the value specified by the
attribute_specifier. Any boolean read-write extended system
attributes associated with the current file that are not
specified by attribute_specifier is cleared.


If an operator is not specified in an attribute_specification, chmod
behaves as if + had been specified.


An attribute_specifier takes one of the following forms:

a

Set all boolean read-write extended system attributes associated
with the current file.


c[compact_attribute_list]
c'{'compact_attribute_list'}'

Set each boolean read-write extended system attribute identified
by compact_attribute_list.


v[verbose_attribute_setting]
v['{'verbose_attribute_setting_list'}']

Set each boolean read-write extended system attribute identified
by verbose_attribute_setting.


A compact_attribute_list is a list of zero or more adjacent attribute
abbreviation characters from list of Attribute Names and
Abbreviation Characters later in this section. An arbitrary number of
hyphen (-) characters can be included in a compact_attribute_list.
These are ignored.


A verbose_attribute_setting is an attribute name from the list of
Attribute Names and Abbreviation Characters later in this section,
optionally, immediately preceded by no. If the attribute name is used
without no, the attribute is set; otherwise the attribute is cleared.


A verbose_attribute_setting_list is zero or more comma-separated
verbose_attribute_settings.


Multiple operations specified for a file are accumulated and are all
set for a file operand as a single attribute setting operation. If an
attribute is specified more than once in an
attribute_specification_list, the last specified operation is
applied.


The following is a list of Attribute Names and Abbreviation
Characters:

Attribute Name
Abbreviation Character


hidden
H


system
S


readonly
R


archive
A


nounlink
u


immutable
i


appendonly
a


nodump
d


av_quarantined
q


av_modified
m


offline
O


sparse
s

OPTIONS

The following options are supported:

-f
Force. chmod does not complain if it fails to
change the mode of a file.


-R
Recursively descend through directory
arguments, setting the mode for each file. When
symbolic links are encountered, the mode of the
target file is changed, but no recursion takes
place.


-@ named_attribute
Perform the attribute operation on the named
extended attribute file of each file operand
instead of the file operand itself. If multiple
-@ operations are supplied, the attribute
specification mode is applied to each of the
named attribute files.

A named attribute of * carries meaning to
chmod, and is considered to mean all extended
attribute files associated with a file operand.
This does not refer to the special files . and
...

A named attribute of .. carries special meaning
to chmod, and is considered to mean the file
operand itself. This allows chmod, in a single
call, to apply the attribute specification mode
to the specified named attribute file of the
file operand and the file operand itself.

OPERANDS

The following operands are supported:

absolute-mode
symbolic-mode-list

Represents the change to be made to the file mode bits of each
file named by one of the file operands. See Absolute Mode and
Symbolic Mode in the DESCRIPTION section of this manual page for
more information.


acl_operation

Represents the modification to be performed on the file's ACL.
See ACL Operation in the DESCRIPTION section for more
information.

acl_operation is one of the following:

A[number] -
A-acl_specification
A[index]{+|=}acl_specification


attribute_specification_list

Represents the modification to performed on the file's
attributes. See Attribute Operation in the DESCRIPTION section of
this manual page for more information.


file

A path name of a file whose file mode bits are to be modified.

USAGE

See largefile(7) for the description of the behavior of chmod when
encountering files greater than or equal to 2 Gbyte (2^31 bytes).

EXAMPLES

Example 1: Denying execute Permission

The following example denies execute permission to everyone:


% chmod a-x file

Example 2: Allowing read-only Permission

The following example allows only read permission to everyone:


% chmod 444 file

Example 3: Making a File readable and writable

The following example makes a file readable and writable by the group
and others:


% chmod go+rw file
% chmod 066 file

Example 4: Locking a File From Access

The following example locks a file from access:


$ chmod +l file

Example 5: Granting read, write, execute, and set group-ID Permission

on a File


The following example grants everyone read, write, and execute
permissions on the file, and turns on the set group-ID:


$ chmod a=rwx,g+s file
$ chmod 2777 file

Example 6: Prepending a New ACL Entry on a ZFS File

The following example prepends a new ACL entry on a ZFS file.


First, display the current ACL:


$ ls -v file.3
-rw-r--r-- 1 marks staff 0 Oct 9 15:49 file.3
0:owner@:execute:deny
1:owner@:read_data/write_data/append_data/write_xattr/
write_attributes/write_acl/write_owner:allow
2:group@:write_data/append_data/execute:deny
3:group@:read_data:allow
4:everyone@:write_data/append_data/write_xattr/execute/
write_attributes/write_acl/write_owner:deny
5:everyone@:read_data/read_xattr/read_attributes/read_acl/
synchronize:allow


Issue the following command:


$ chmod A+user:lp:read_data:deny file.3


Display the new ACL:


$ ls -v file.3
-rw-r--r--+ 1 marks staff 0 Oct 9 15:49 file.3
0:user:lp:read_data:deny
1:owner@:execute:deny
2:owner@:read_data/write_data/append_data/write_xattr/
write_attributes/write_acl/write_owner:allow
3:group@:write_data/append_data/execute:deny
4:group@:read_data:allow
5:everyone@:write_data/append_data/write_xattr/execute/
write_attributes/write_acl/write_owner:deny
6:everyone@:read_data/read_xattr/read_attributes/read_acl/
synchronize:allow

Example 7: Prepending a New POSIX-draft ACL Entry on a UFS File

The following example prepends a new POSIX-draft ACL entry on a UFS
file.


First, display the current ACL:


$ ls -v file.2
-rw-r--r-- 1 marks staff 0 Oct 9 15:52 file.2
0:user::rw-
1:group::r-- #effective:r--
2:mask:r--
3:other:r--


Issue the following command:


$ chmod A+user:lp:-wx file.2


Display the new ACL:


$ ls -v file.2
-rw-r--r--+ 1 marks staff 0 Oct 9 15:52 file.2
0:user::rw-
1:user:lp:-wx #effective:---
2:group::r-- #effective:r--
3:mask:r--
4:other:r--

Example 8: Inserting an ACL Entry in a Specific Position on a ZFS file

The following example inserts an ACL entry in a specific position on
a ZFS file system. It also illustrates the compact ACL format.


First, display the ACL to pick a location to insert a new ACE.


% ls -V file.1
-rw-r--r--+ 1 root root 0 Oct 6 12:16 file.1
user:lp:rw------------:-------:allow
owner@:--x-----------:-------:deny
owner@:rw-p---A-W-Co-:-------:allow
group@:-wxp----------:-------:deny
group@:r-------------:-------:allow
everyone@:-wxp---A-W-Co-:-------:deny
everyone@:r-----a-R-c--s:-------:allow


Next, insert a new entry in location 3. This causes the entries
that are currently in position 3 - 6 to be pushed down.


Issue the following command:


$ chmod A3+user:marks:r:deny file.1


Display the new ACL:


$ ls -V file.1
-rw-r--r--+ 1 root staff 0 Feb 3 14:13 file.1
user:lp:rw------------:-------:allow
owner@:--x-----------:-------:deny
owner@:rw-p---A-W-Co-:-------:allow
user:marks:r-------------:-------:deny
group@:-wxp----------:-------:deny
group@:r-------------:-------:allow
everyone@:-wxp---A-W-Co-:-------:deny
everyone@:r-----a-R-c--s:-------:allow

Example 9: Inserting a POSIX-draft ACL in a Specific Position on a UFS

File


The file system reorders ACLs when they are stored in the file
system. The following example illustrates this behavior.


$ ls -v file.1
-rw-r--r--+ 1 root root 0 Sep 29 16:10 file.1
0:user::rw-
1:user:lp:rw- #effective:r--
2:group::r-- #effective:r--
3:mask:r--
4:other:r--


Now, insert an entry at index position 3. The command works, but the
file system reorders the ACL.


$ chmod A3+user:marks:rw- file.1
$ ls -v file.1
-rw-r--r--+ 1 root root 0 Sep 29 16:10 file.1
0:user::rw-
1:user:lp:rw- #effective:r--
2:user:marks:rw- #effective:r--
3:group::r-- #effective:r--
4:mask:r--
5:other:r--


Rather than inserting the ACL entry in position 3 as requested, it
actually ends up in position 2.

Example 10: Removing an ACL Entry on a ZFS File

The following example removes the lp entry from an ACL:


$ ls -v file.3
-rw-r--r--+ 1 marks staff 0 Oct 9 15:49 file.3
0:user:lp:read_data:deny
1:owner@:execute:deny
2:owner@:read_data/write_data/append_data/write_xattr/
write_attributes/write_acl/write_owner:allow
3:group@:write_data/append_data/execute:deny
4:group@:read_data:allow
5:everyone@:write_data/append_data/write_xattr/execute/
write_attributes/write_acl/write_owner:deny
6:everyone@:read_data/read_xattr/read_attributes/read_acl/
synchronize:allow


$ chmod A-user:lp:read_data:deny file.3
$ ls -v file.3
-rw-r--r-- 1 marks staff 0 Oct 9 15:49 file.3
0:owner@:execute:deny
1:owner@:read_data/write_data/append_data/write_xattr/
write_attributes/write_acl/write_owner:allow
2:group@:write_data/append_data/execute:deny
3:group@:read_data:allow
4:everyone@:write_data/append_data/write_xattr/execute/
write_attributes/write_acl/write_owner:deny
5:everyone@:read_data/read_xattr/read_attributes/read_acl/
synchronize:allow

Example 11: Removing a POSIX-draft ACL on a UFS File

The following example removes the lp entry from an ACL:


$ ls -v file.2
-rw-r--r--+ 1 marks staff 0 Oct 9 15:52 file.2
0:user::rw-
1:user:lp:-wx #effective:---
2:group::r-- #effective:r--
3:mask:r--
4:other:r--


$ chmod A-user:lp:-wx file.2
$ ls -v file.2
-rw-r--r-- 1 marks staff 0 Oct 9 15:52 file.2
0:user::rw-
1:group::r-- #effective:r--
2:mask:r--
3:other:r--

Example 12: Removing a Specific ACL Entry by Index Number on a ZFS

File


Consider the following ACL:


$ ls -v file
0:group:staff:read_data/write_data/execute/read_acl:allow
1:user:bin:read_data:deny
2:user:bin:read_data:allow
3:owner@:write_data/append_data:deny
4:owner@:read_data/write_xattr/execute/write_attributes/write_acl
/write_owner:allow
5:group@:write_data/append_data:deny
6:group@:read_data/execute:allow
7:everyone@:write_data/append_data/write_xattr/write_attributes
/write_acl/write_owner:deny
8:everyone@:read_data/read_xattr/execute/read_attributes/read_acl
/synchronize:allow


Remove the second user entry for bin.


$ chmod A2- file
$ ls -v file
0:group:staff:read_data/write_data/execute/read_acl:allow
1:user:bin:read_data:deny
2:owner@:write_data/append_data:deny
3:owner@:read_data/write_xattr/execute/write_attributes/write_acl
/write_owner:allow
4:group@:write_data/append_data:deny
5:group@:read_data/execute:allow
6:everyone@:write_data/append_data/write_xattr/write_attributes
/write_acl/write_owner:deny
7:everyone@:read_data/read_xattr/execute/read_attributes/read_acl
/synchronize:allow

Example 13: Removing a Specific POSIX-draft ACL Entry on a UFS File

The following example removes the lp entry by index number from the
following ACL:


$ ls -v file.1
-rw-r--r--+ 1 root root 0 Sep 29 16:10 file.1
0:user::rw-
1:user:lp:rw- #effective:r--
2:group::r-- #effective:r--
3:mask:r--
4:other:r--

$ chmod A1- file.1
$ ls -v
-rw-r--r--+ 1 root root 0 Sep 29 16:10 file.1
0:user::rw-
1:group::r-- #effective:r--
2:mask:r--
3:other:r--

Example 14: Removing All ACLs From a File

The following command works with either NFSv4/ZFS or POSIX-draft
ACLs.


Consider the following ACL:


$ ls -v file.3
-rw-r--r--+ 1 marks staff 0 Oct 9 15:49 file.3
0:user:lp:read_data/write_data:allow
1:user:marks:read_acl:allow
2:owner@:execute:deny
3:owner@:read_data/write_data/append_data/write_xattr/
write_attributes/write_acl/write_owner:allow
4:group@:write_data/append_data/execute:deny
5:group@:read_data:allow
6:everyone@:write_data/append_data/write_xattr/execute/
write_attributes/write_acl/write_owner:deny
7:everyone@:read_data/read_xattr/read_attributes/read_acl/
synchronize:allow


The existing ACL is effectively removed and is replaced with an ACL
that represents the permission bits of the file.


$ chmod A- file.3
$ ls -v file.3
-rw-r--r-- 1 marks staff 0 Oct 9 15:49 file.3
0:owner@:execute:deny
1:owner@:read_data/write_data/append_data/write_xattr/
write_attributes/write_acl/write_owner:allow
2:group@:write_data/append_data/execute:deny
3:group@:read_data:allow
4:everyone@:write_data/append_data/write_xattr/execute/
write_attributes/write_acl/write_owner:deny
5:everyone@:read_data/read_xattr/read_attributes/read_acl/
synchronize:allow

Example 15: Replacing an Entire ACL Entry on a ZFS File

Use the following chmod syntax if you want to replace an ACL in its
entirety:


$ chmod A=owner@:read_data/write_data:allow,group@:read_data/
write_data:allow,user:lp:read_data:allow file.4
$ ls -v file.4
-rw-rw----+ 1 marks staff 0 Oct 9 16:12 file.4
0:owner@:read_data/write_data:allow
1:group@:read_data/write_data:allow
2:user:lp:read_data:allow

Example 16: Replacing an Entire POSIX-draft ACL on a UFS File

This operation is a little more complicated. The replacement ACL
needs the necessary entries to represent the file owner, file group
owner, other, mask and any additional entries you wish to set.


$ chmod A=user::rw-,group::rw-,other::---,mask:r--,
user:lp:r-- file.3
$ ls -v file.3
-rw-r-----+ 1 root root 0 Oct 9 16:14 file.3
0:user::rw-
1:user:lp:r-- #effective:r--
2:group::rw- #effective:r--
3:mask:r--
4:other:---

Example 17: Replacing a Specific Entry on a ZFS File

Consider the following ACL.


$ ls -v file.5
-rw-r--r--+ 1 marks staff 0 Oct 9 16:18 file.5
0:user:marks:read_data:allow
1:owner@:execute:deny
2:owner@:read_data/write_data/append_data/write_xattr/
write_attributes/write_acl/write_owner:allow
3:group@:write_data/append_data/execute:deny
4:group@:read_data:allow
5:everyone@:write_data/append_data/write_xattr/execute/
write_attributes/write_acl/write_owner:deny
6:everyone@:read_data/read_xattr/read_attributes/read_acl/
synchronize:allow


Now, change the allow access to a deny for user marks:


$ chmod A0=user:marks:read_data:deny file.5
$ ls -v file.5
-rw-r--r--+ 1 marks staff 0 Aug 23 09:11 file.5
0:user:marks:read_data:deny
1:owner@:read_data/write_data/append_data/write_xattr/write_attributes
/write_acl/write_owner:allow
2:group@:write_data/append_data/execute:deny
3:group@:read_data:allow
4:everyone@:write_data/append_data/write_xattr/execute/write_attributes
/write_acl/write_owner:deny
5:everyone@:read_data/read_xattr/read_attributes/read_acl/synchronize
:allow

Example 18: Replacing a Specific POSIX-draft ACL on a UFS File

Consider the following ACL.


$ ls -v file.4
-rw-r--r--+ 1 marks staff 0 Oct 9 16:21 file.4
0:user::rw-
1:user:lp:rwx #effective:r--
2:group::r-- #effective:r--
3:mask:r--
4:other:r--


Now, change the permission on lp from rwx to r--:


$ chmod A1=user:lp:r-- file.4

$ ls -v file
-rw-r--r--+ 1 marks staff 0 Oct 9 16:21 file.4
0:user::rw-
1:user:lp:r-- #effective:r--
2:group::r-- #effective:r--
3:mask:r--
4:other:r--

Example 19: Setting ACL Inheritance Flags on a ZFS File

You can only set inheritance flags on ZFS files. When setting ACLs on
directories, several inheritance flags can be optionally set.


Suppose you have an ACL entry for user lp that you want to be
inherited to newly created files in a directory. First, you need to
create an inheritable ACL entry on the directory:


$ chmod A+user:lp:read_data:file_inherit:allow test.dir
$ ls -dv test.dir
drwxr-xr-x+ 2 marks staff 2 Aug 23 09:08 test.dir/
0:user:lp:read_data:file_inherit:allow
1:owner@::deny
2:owner@:list_directory/read_data/add_file/write_data/add_subdirectory
/append_data/write_xattr/execute/write_attributes/write_acl
/write_owner:allow
3:group@:add_file/write_data/add_subdirectory/append_data:deny
4:group@:list_directory/read_data/execute:allow
5:everyone@:add_file/write_data/add_subdirectory/append_data/write_xattr
/write_attributes/write_acl/write_owner:deny
6:everyone@:list_directory/read_data/read_xattr/execute/read_attributes
/read_acl/synchronize:allow


The lp entry is inherited to newly created files in the directory
test.dir.


$ touch test.dir/file.test
$ ls -v test.dir/file.test
-rw-r--r--+ 1 marks staff 0 Oct 9 16:29 test.dir/file.test
0:user:lp::deny
1:user:lp:read_data:allow
2:owner@:execute:deny
3:owner@:read_data/write_data/append_data/write_xattr/
write_attributes/write_acl/write_owner:allow
4:group@:write_data/append_data/execute:deny
5:group@:read_data:allow
6:everyone@:write_data/append_data/write_xattr/execute/
write_attributes/write_acl/write_owner:deny
7:everyone@:read_data/read_xattr/read_attributes/read_acl/
synchronize:allow


The user lp entry is inherited to the newly created file. Multiple
combinations of the inheritance flags can be specified. For example,
if you wanted the lp entry to also be inherited to directories, then
the following command can be used:


$ chmod A+user:lp:read_data:file_inherit/\
dir_inherit:allow test.dir

Example 20: Replacing System Attributes of a ZFS File

The following examples replace system attributes of a ZFS file:


$ chmod S=v{archive,hidden,readonly,system,appendonly,\
nonodump,immutable,noav_modified,noav_quarantined,\
nounlink,nooffline,nosparse} file1


or


$ chmod S=c{AHRSaiu} file1


or


$ chmod S=c{AHRSa-i--u--} file1


or


$ chmod S=cAHRSaiu file1


or


$ chmod -@ '..' S=cAHRSaiu file1


Assuming appropriate privileges, this results in the following system
attributes of file1 being set: archive, hidden, readonly, system,
appendonly, immutable, and nounlink. Assuming appropriate privileges,
the following system attributes of file1 are cleared: nodump,
av_modified, av_quarantined, offline, and sparse.

Example 21: Clearing All System Attributes of a ZFS File

The following examples clears all system attributes of a ZFS file:


$ chmod S-a file1


or


$ chmod -@ '..' S-a file1


Assuming appropriate privileges, all boolean read-write system
attributes are cleared on file1.

Example 22: Setting a System Attribute of a Named Attribute File of a

ZFS File


The following example sets a system attribute of a named attribute
file of a ZFS file, but not of the file itself:


$ chmod -@ myattr S+vhidden file1


This results in the hidden system attribute being set for the named
attribute file myattr of file1, but not the file itself.

Example 23: Setting a System Attribute of All Named Attribute File of

a ZFS File


The following example sets a system attribute of all named attribute
files of a ZFS file, but not of the file itself:


$ chmod -@ '*' S+a file1

Example 24: Setting a System Attribute of All Named Attribute Files of

a ZFS File


The following example sets a system attribute of all named attribute
files of a ZFS file, as well as of the file itself:


$ chmod -@ '..' -@ '*' S+vhidden file1


This results in the hidden system attribute being set for all named
attribute files of file1, as well as the file itself.

Example 25: Recursively Descending Through a Directory Hierarchy

The following example recursively descends through a directory
hierarchy, and sets all system attributes of all named attribute
files, the ZFS file operands, as well as of the directory itself:


$ chmod -R -@ '..' -@ '*' S+a directory1


This results in the hidden system attribute being set for all named
attribute files of all regular files and directories within the
directory hierarchy of directory1, as well as of directory1 itself.

Example 26: Setting the hidden and system System Attributes of a ZFS

File


The following examples set the hidden and system system attributes of
a ZFS file:


$ chmod S+cHS file1


or


$ chmod S+vhidden,+vsystem file1


or


$ chmod S+v{hidden,system} file1


or


$ chmod S+c{-H-S--------} file1


or


$ chmod S-v{nohidden,nosystem} file1


or


$ chmod S-v{hidden,system},+v{hidden,system} file1

Example 27: Clearing All System Attributes of a ZFS File

The following example clears all system attributes of a ZFS file:


$ chmod S-a file1


or


$ chmod S=v{} file1


In the following two examples, the last attribute operation specified
takes precedence.


In this example, the replacement attribute name list ({}) clears all
system attributes for file1:


$ chmod S+cHS,=v{} file1


In this example, the clear attributes operation (-a) clears all
system attributes of file1:


$ chmod S+vhidden,+vsystem,-a file1

Example 28: Setting the Values of All Boolean read-write System

Attributes of a File


The following example sets the values of all boolean read-write
system attributes of a file to the same as the boolean read-write
system attributes of another file:


$ chmod S=v`ls -/v file1|sed -n '2s/.*{/{/p'` file2


Assuming appropriate privileges and that file1 and file2 have the
same supported system attributes, all system attributes of file1 that
are set are also set on file2. All system attributes of file1 that
are cleared are also cleared on file2.

ENVIRONMENT VARIABLES

See environ(7) for descriptions of the following environment
variables that affect the execution of chmod: LANG, LC_ALL, LC_CTYPE,
LC_MESSAGES, and NLSPATH.

EXIT STATUS

The following exit values are returned:

0
Successful completion.


>0
An error occurred.

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|CSI | Enabled |
+--------------------+-----------------+
|Interface Stability | Committed |
+--------------------+-----------------+

SEE ALSO

getfacl(1), ls(1), setfacl(1), chmod(2), fgetattr(3C), acl(7),
attributes(7), environ(7), fsattr(7), largefile(7), standards(7)

NOTES

Absolute changes do not work for the set-group-ID bit of a directory.
You must use g+s or g-s.


chmod permits you to produce useless modes so long as they are not
illegal (for instance, making a text file executable). chmod does not
check the file type to see if mandatory locking is meaningful.


If the filesystem is mounted with the nosuid option, setuid execution
is not allowed.


If you use chmod to change the file group owner permissions on a file
with ACL entries, both the file group owner permissions and the ACL
mask are changed to the new permissions. Be aware that the new ACL
mask permissions can change the effective permissions for additional
users and groups who have ACL entries on the file. Use the getfacl(1)
or ls(1) command to make sure the appropriate permissions are set for
all ACL entries.

November 24, 2014 CHMOD(1)