setacl(1)setacl(1)NAMEsetacl - Changes the specified access control list (ACL) on a file or
directory
SYNOPSISsetacl [-a] [-d] [-D] [-b] [-E] [-k] [-K] [-x entries] [-X file1] [-u
entries] [-U file2] filename...
OPTIONS
Specifies that the operation applies to the access ACL. This option is
implied if none of -a, -d, or -D is supplied. Delete the access ACL on
the specified file or directory. The permission bits are not removed or
changed in this operation, and the permission bits are considered to be
the “base” entries of an ACL, so this can be considered equivalent to
resetting the access ACL to just the base entries (u::, g::, o::). The
operation applies to the default access ACL. Default ACLs can only be
set on directories, an error is returned if this operation applies to a
file instead of a directory. Default ACLs must contain at least the 3
base entries entries of the directory's access ACL (or the directory's
permission bits if it does not have an access ACL). You should specify
values for the 3 base entries if the current value in the access ACL is
not appropriate.
The -d option is not defined by POSIX. [Tru64 UNIX] The opera‐
tion applies to the default directory ACL. Default ACLs can only
be set on directories, an error is returned if this operation
applies to a file instead of a directory. Default ACLs must
contain at least the 3 base entries (the entries that correspond
to the permission bits). When you first create a default ACL, if
you do not specify these 3 entries they default to the current
value of the 3 base entries of the directory's access ACL (or
the directory's permission bits if it does not have an access
ACL). You should specify values for the 3 base entries if the
current value in the access ACL is not appropriate.
The -D option is not defined by POSIX. [Tru64 UNIX] Invoke the
character cell ACL editor. Delete the default access ACL for
the designated directory. No error is returned if the designated
directory does not have a default access ACL. An error is
returned if this operation is applied to a file instead of a
directory. If the -k option is specified and the -d option is
not specified, all the other options apply to the access ACL,
not the default access ACL. [Tru64 UNIX] Delete the default
directory ACL for the designated directory. No error is returned
if the designated directory does not have a default directory
ACL. An error is returned if this operation is applied to a
file instead of a directory. If the -K option is specified and
the -d option is not specified, all the other options apply to
the access ACL, not the default directory ACL. Removes the ACL
entries listed in file1 from the specified ACL of the designated
file or directory. Removes the specifed entries from the speci‐
fied ACL of the designated file or directory. Updates the ACL
with the specified entries. Matching entries are modified or
overwritten, new entries are added. An entry is considered
matching if the tag type and tag qualifier are the same. See the
Format of an ACL Entry section for a description of the format
of ACL entries and how they are modified. Updates the ACL with
the entries specified in file2. Matching entries are modified
or overwritten, new entries are added. An entry is considered
matching if the tag type and tag qualifier are the same. See
the Format of an ACL Entry section for a description of the for‐
mat of ACL entries and how they are modified.
The -a, -d, and -D options are not mutually exclusive; they can all be
specified, and all are set. If none are specified the -a option is
assumed. The -d and -D options only apply to directories.
The -b option is applied before any of the -u, -U, -x, or -X options
Multiple -u, -U, -x, and -X options are all applied to the ACL in the
order listed on the command line. All of options are applied to a tem‐
porary copy of the ACL before the ACL is applied to the files. It is
not an error for an intermediate version of the ACL to be ill formed,
as long as the ACL is well formed by the time it is applied.
Several options accept arguments of the following types: The ACL
entries used to perform the requested operation. Multiple ACL entries
are separated by commas. There is no required ordering of entries. A
file containing ACL entries to use to perform the requested operation.
Each entry should be on a separate line. There is no required ordering
of entries. If a line contains the comment character, #, setacl ignores
the line.
ACLs may be set on files and directories if ACLs are disabled on the
system, but ACL access checks and ACL inheritance won't take place. The
setacl command will print a warning if ACLs are disabled on the system.
Not all types of filesystems support ACLs. The setacl command will
fail if ACLs are not supported on the filesystem.
DESCRIPTION
Note
This command is based on Draft 13 of the POSIX P1003.6 standard.
The setacl command is used to add, modify, and remove access control
lists (ACL) and individual ACL entries on files and directories.
Files only have one ACL, an access ACL. Directories may have up to 3
ACLs, an access ACL, a default access ACL, and a default directory ACL.
The default ACLs are used to specify ACLs to be inherited by new files
and subdirectories created within the directory. See the acl(4) refer‐
ence page and the Security guide for more information on ACL types and
ACL inheritance.
Format of an ACL Entry
The external representation of an ACL entry consists of three colon (:)
separated fields. The first field is a tag type, the second field con‐
tains optional qualifiers whose meaning depend on the tag type, and the
third field is a list of the permissions. The following examples are
typical:
user::rwx user:jdoe:rw- user:mightymouse:r-- user:bsmith:rwx group::r--
other::---
The tag types and associated qualifiers are: If the qualifier field is
empty, the user tag type defines the permissions for the user who owns
the file or directory. This entry should be considered exactly the same
as the owning user permission bits. Setting this entry will cause the
appropriate change in the permission bits. The user tag type with a
username or uid as a tag qualifier defines the permissions for the
given user. If a numeric user name exists in the user database, the uid
associated with that user name will be used as the entry uid. For
example if there is a user name “39456” with uid 420, a user name
“fred” with uid 39456, and you create the entry “user:39456:rwx”; the
uid 420 will be associated with the ACL entry, not the uid 39456. If
the qualifier field is empty, the group tag type defines the permis‐
sions of users who are members of the group associated with the file or
directory. This entry should be considered exactly the same as the
owning group permission bits. Setting this entry will cause the appro‐
priate change in the permission bits. The group tag type with a group‐
name or gid as a tag qualifier defines the permissions for members of
the given group. If a numeric group name exists in the group database,
the gid associated with that group name will be used as the entry gid.
For example if there is a group name “521” with gid 40, a group name
“mygroup” with gid 521, and you create the entry “group:521:r--”; the
gid 40 will be associated with the ACL entry, not the gid 521. No
qualifiers are allowed for the other tag type. The other tag type
defines the permissions for users who are not covered by any other ACL
entries. This entry should be considered exactly the same as the other
permission bits. Setting this entry will cause the appropriate change
in the permission bits.
The third field specifies the discretionary access permissions. They
are:
Letter Octal PERMISSION
r 4 Read access
w 2 Write access
x 1 Execute/Search across
- 0 No access
A set of permissions in an ACL entry is internally represented in three
bits. The permissions are displayed as a character string, similar to
the way that ls -l displays permissions.
The set of permissions can be specified in three ways: As a single
octal digit. Add the numbers shown above to determine the permissions.
The value 0 (zero), for example, specifies no permissions, and the
value 7 specifies all permissions. As an absolute character string. An
absolute character string contains three characters. The first speci‐
fies read permission, the second write permission, and the third speci‐
fies execute/search permission. To grant all permissions, specify rwx
in that order. To deny one or more permissions, use the character - in
the appropriate positions. For example, the entry r-x grants read and
execute/search permissions and denies write permission. As a relative
character string. A relative character string adds or removes permis‐
sions from the existing set. To add permissions, specify a + followed
by one or more permission letters. For example, +r adds read permission
to the existing set. To remove permissions, specify a ^ followed by one
or more permission letters. For example, ^x removes execute/search
permission. Some shells consider ^ as a special character. You may
need to escape the character by preceeding it with a back slash (\) or
surrounding it with double quotes ("^").
Both octal digits and absolute character strings set the permissions to
the specified values. One of these forms should be used for new
entries.
Relative permissions modify an existing ACL entry (options -u and -U)
with an input entry that matches in tag type and tag qualifier. If
setacl adds an entry to an ACL, a + prefix is ignored and the set of
permissions is entered as an absolute string; if the prefix is ^, the
permissions field is set to no access. If an entry is to be removed
from an ACL, input permissions are ignored altogether.
Suppose an ACL entry is specified with relative permissions,
group:dec:\^wx (remove wx permissions)
to be applied to a matching entry with permissions r-x. The matching
entry will have a new set of permissions as follows:
group:dec:r-- (read only)
Format of an ACL
An ACL contains at least three base tag type entries: A user entry with
no qualifiers A group entry with no qualifiers An other entry
In an access ACL, these three entries are equivalent to the permission
bits of the file or directory.
An ACL also has one or more user or group entries with qualifiers, for
example:
user::rw group::rw- user:user1:r-x group:dec:--x other::rwx
The entry group::rw- is the file group owner and specifies the read and
write permissions.
AUTHORIZATIONS
To change or remove the ACL of a file or directory, the user must
either own the file or directory or be privileged (root).
EXIT STATUS
If setacl is invoked incorrectly or cannot decipher the specified ACL,
it returns an exit status of 1. The setacl command returns an exit
status of 0 (zero) if all files are changed.
ERRORS
The setacl command displays an error message explaining why the ACL
could not be changed.
EXAMPLES
Assume that the ACL on a file named shared contains the following mini‐
mum entries:
user::rwx group::r-x other::---
The following command updates and adds entries: $ setacl-u
group::r--,user:alpha:-w- shared
The resulting ACL entries are:
user::rwx user:alpha:-w- group::r-- other::---
The owning group entry on the command line matches the existing
group entry, so the permission set is reduced to read only. The
user entry on the command line does not match an existing entry
and is added. Assume that the ACL on a file named shared con‐
tains the following entries:
user::rwx user:user1:-w- group::-w- group:dec:-wx other::---
Apply the setacl-u command (update) to the shared file as fol‐
lows: $ setacl-u user:user1:-wx shared
The resulting ACL entries are:
user::rwx user:user1:-wx- group::-w- group:dec:-wx other::---
Assume that the directory foo contains no default ACLs, and the
following command is issued: $ setacl-d-u
user::rw-,group::r--,other::r--,user:dec:rw- foo
Any file or directory that is created within the directory foo
now inherits the following ACL as the access ACL:
user::rw- user:dec:r-- group::r-- other::r--
Any directory also inherits the same ACL as the default access
ACL. Assume that the directory foo contains no default ACLs,
and the following command is issued: $ setacl-D-u
user::rwx,group::r-x,other::---,user:dec:r-x foo
Any directory that is created within the directory foo now
inherits the following ACL as the access ACL, as well as its
default directory ACL:
user::rwx user:dec:r-x group::r-x other::---
Any file does not inherit an ACL. File permissions are set in
the same way as they are without ACLs. Assume that the direc‐
tory foo contains no default ACLs, the 3 base entries of the
access ACL on directory foo are u::rwx, group::r-x, other::r-x,
and the following commands are issued: $ setacl-D-u
user:dec:r-- foo $ setacl-d-u
user::rw-,group::r--,other::---,user:alpha:r-- foo
Any directory that is created within the directory foo now
inherits the default directory ACL of foo as its access ACL as
well as its default directory ACL:
user::rwx user:dec:r-- group::r-x other::r-x
In addition, any directory that is created within the directory
foo inherits the default access ACL of foo as its default access
ACL:
user::rw- user:alpha:r-- group::r-- other::r--
Any file created in directory foo inherits the default access
ACL of foo as its access ACL:
user::rw- user:alpha:r-- group::r-- other::r--
SEE ALSO
Commands: getacl(1)
Files: acl(4)
Security
setacl(1)
