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)