setacl(1) General Commands Manual setacl(1)
NAME
setacl - Changes the specified access control list (ACL) on a file or directory
SYNOPSIS
setacl [-a] [-d] [-D] [-b] [-E] [-k] [-K]
[-x entries]
[-X file1] [-u entries]
[-U file2] filename ...
FLAGS
Specifies that the operation applies to the access ACL. This flag 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 consid-
ered 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 flag is not defined by POSIX. [Tru64 UNIX] The operation 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 flag 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 flag is specified and the -d flag is not specified, all the other flags 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 flag is specified and the -d flag is not specified, all the other flags 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 specified ACL of the designated file or directory. Updates the ACL with the specified entries. Matching entries are mod-
ified or overwritten, new entries are added. An entry is considered matching if the tag type and tag qualifier are the same. See the For-
mat 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 format of ACL entries and how they are
modified.
The -a, -d, and -D flags are not mutually exclusive; they can all be specified, and all are set. If none are specified the -a flag is
assumed. The -d and -D flags only apply to directories.
The -b flag is applied before any of the -u, -U, -x, or -X flags
Multiple -u, -U, -x, and -X flags are all applied to the ACL in the order listed on the command line. All of flags are applied to a tempo-
rary 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 flags 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
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) reference 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
contains 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 per-
mission 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 permissions of users who are mem-
bers 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 appropriate change in the permission bits. The group tag type with a groupname 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 per-
mission 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 access - 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 specifies 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 permissions 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 char-
acter. 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 (flags -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::rwx
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).
EXAMPLES
Assume that the ACL on a file named shared contains the following minimum 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 contains 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 follows:
$ 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 fol-
lowing 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 directory foo con-
tains 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--
EXIT VALUES
If setacl is invoked incorrectly or cannot decipher the specified ACL, it returns an exit status of 1. setacl 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.
RELATED INFORMATION
Commands: getacl(1)
Files: acl(4)
Security delim off
setacl(1)