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ACL Operations in Solaris

There just two main commands to work with ACLs:

• -a Displays the filename, owner, group, and ACL of the file.
• -d Displays the filename, owner, and group of the file.

setfacl Sets, adds, modifies, and deletes ACL entries.  Has a half-dozen options:

• -s acl_entries Sets the ACL for the file, removing all old entries and replacing them with the newly specified ACL.
•  -m acl_entries Adds one or more new ACL entries to the file or modifies one or more existing ACL entries for the file. If an entry already exists, the specified permissions replace the current permissions. If no entry exists, a new entry is created.
• -d acl_entries Deletes one or more entries from the file. You cannot delete entries for the file owner, the owning group, and other. Note that deleting an entry does not necessarily have the same result as removing all permissions from the entry.
• -f acl_file Specifies a file containing the ACL entries to be used as arguments to the setfacl command.
• -r Recalculates permissions for the ACL mask. Permissions specified in the mask are ignored and replaced by the maximum permissions needed to give access to any additional user, owning group, and additional group entries in the ACL.

Each ACL entry consists of the following fields, which are separated by colons:

<entry-type>:[<UID>] | [<GID>]:<perms>

Where

• <entry-type> Type of ACL entry on which to set file permissions. For example, <entry_type> can be user (the owner of a file) or mask (the ACL mask).
  •  m[ask] Sets the ACL mask. The mask entry indicates the maximum permissions allowed for users other than the owner and for groups. Using the mask is a quick way to change permissions on all of the users and groups. For example, the mask:r-- and mask:4 entry indicates that users and groups cannot have more than read permissions, even though they may have write/execute permissions.
  •  u[ser]Sets the permissions for a specific user.
  •  g[roup] Sets the permissions for a specific group.
• <UID> Username or identification number.
• <GID> Group name or identification number.
• <perm> Permissions set for the <entry-type>. Permissions can be set symbolically using the characters r, w, x, and - or by using octal values from 0 to 7.

You can also set regular permissions:

•  u[ser]::<perm> Sets the permissions for the owner of the file.

•  g[roup]::<perm> Sets the permissions for the owner's group.

•  o[ther]::<perm> Sets the permissions for users other than the owner or members of the owner's group.

You can determine if a file has an ACL in one of two ways:

•  By using the ls -l command

•  By using the getfacl command

When you use the ls -l command, any file that has an ACL displays a plus (+) sign to the right of the mode field.

NOTE:  If you define an ACL for a file and do not specify any additional users or groups, the plus sign is not displayed to the right of the mode field even though the file has a basic ACL. The plus sign is displayed only if additional users or groups are included in the ACL.

When you use the getfacl <filename> command with no options, the ACL information for the file is displayed.

NOTE:  You can use the getfacl command to display permissions on any UFS file or directory in the same format. The file does not need to have an ACL.

For comparison, the following example shows the output of the ls -l and getfacl commands for the file bar, which does not have an ACL.

castle% ls -l bar
-rwxrw—       1 winsor  staff     0 Oct 3 14:22 bar
castle% getfacl bar

# file: bar
# owner: winsor
# group: staff
user::rwx
group::rw-           #effective:rw-
mask:rw-
other:—
castle%

Use the setfacl command to set ACL permissions on a file. You can set the permissions for a file or a group of files from a command line or by listing the permissions in a file and using the file as an argument to the setfacl command. You can specify the permissions with the following syntax:

u[ser]::<perm>
u[ser]:uid:<perm>
g[roup]::<perm>
g[roup]:gid:<perm>
m[ask]:<perm>
o[ther]:<perm>
d[efault]:u[ser]::<perm>
d[efault]:u[ser]:uid:<perm>
d[efault]:g[roup]::<perm>
d[efault]:g[roup]:gid:<perm>
d[efault]:m[ask]:<perm>
d[efault]:o[ther]:<perm>

NOTE:  You can use either octal or symbolic values to set permissions.

On a command line, use a comma to separate each permission statement. In an ACL file, put each statement on a separate line. The statements do not need to be in any particular order.

setfacl: Setting Permissions for a File from a Command Line

To set ACL permissions from a command line, you must specify at least the basic set of user, group, other, and mask permissions. Type the following command to set ACL permissions: setfacl -s u::<perm>,g::<perm>,o:<perm>, m:<perm>, [u:<UID>:<perm>], [g:<GID>:<perm>

You can set users by using either their username or their UID number. Note that before you can use the username argument, the user account must already exist in the Passwd database or in the local /etc/passwd file. You can assign permissions to any UID by number, regardless of whether a user account exists.

In the same way, you can set group names by using either the group name or the GID number.

The following example assigns all of the permissions to the user, restricts group permissions to read-only, and denies permissions to other. The default mask sets read-write permissions, and user ray is assigned read-write permissions to the file foo.

First, take a look at the current permissions for the file:

castle% ls -l foo
-rw-rw-rw-    1 winsor       staff      0 Oct 3 14:22 foo

Then set permissions for user, group, owner, and the mask and add one user to the ACL:

castle% setfacl -s u::rwx,g::r—,o:—,mask:rw-,u:ray:rw- foo

Using octal values, as shown in the following example, gives you the same result:

castle% setfacl -s u::7,g::4,o:0,mask:6,u:ray:6 foo

Next, verify that the permissions have been set and that the file has an ACL:

castle% ls -l foo
-rwxrw—    +  1 winsor   staff      0 Oct  3 14:22 foo

As you can see, the permissions for the file are changed and the plus sign after the permission field shows that the file has an ACL. Last, use the getfacl command to verify that everything has been set correctly:

castle% getfacl foo

# file: foo
# owner: winsor
# group: staff
user::rwx
user:ray:rw-         #effective:rw-
group::rw-           #effective:rw-
mask:rw-
other:—
castle%

The getfacl command always displays ACL permissions symbolically, regardless of how you specify the values from the command line.

You can create an ACL configuration file that contains a list of the permissions you want to set and then use that filename as an argument to the setfacl -s command.

NOTE:  You can use a configuration file only with the -s option to the setfacl command.

Use the following steps to set up the ACL configuration file:

1.  Use any editor to create a file.

2.  Edit the file to include the permissions you want to set, putting each statement on a separate line. Be sure to include permissions for user, group, other, and mask as a minimum set.

3.  Save the file by using any filename you choose.

4.  Type setfacl -f <acl_filename> <filename1> [<filename2>] [<filename3>] and press Return.

5.  Type getfacl <filename1> [<filename2>] [<filename3>] and press Return to verify that the permissions are set correctly.

NOTE:  If you make typographical errors in the configuration file, the command might return a prompt without displaying any error messages. If you make syntax errors, the setfacl command might display an error message. Be sure to use the getfacl command to check that the permissions are set properly.

In the following example, the owner has rwx permissions, group has rw-, other has —, and the mask is rw-. Three users with different permissions are also granted access to the file. The acl_file (named anything) contains the following access list:

u::rwx
g::rw-
o:—
m:rw-
u:ray:rwx
u:des:rw-
u:rob:r—

Once you have set up the ACL for the file named anything, you can use the setfacl -f option to assign those same permissions to one more file. In the following example, the file named anything is used as the argument to the -f option to change ACLs for the files foo and bar so that they match the file anything:

castle% setfacl -f anything foo bar
castle% getfacl foo bar

# file: foo
# owner: winsor
# group: staff
user::rwx
user:ray:rwx         #effective:rwx
user:des:rw-         #effective:rw-
user:rob:r—         #effective:r—
group::rw-           #effective:rw-
mask:rw-
other:—

# file: bar
# owner: winsor
# group: staff
user::rwx
user:ray:rwx         #effective:rwx
user:des:rw-         #effective:rw-
user:rob:r—         #effective:r—
group::rw-           #effective:rw-
mask:rw-
other:—
castle%

Adding and Modifying ACL Permissions

You can add and modify ACL permissions for a file that already has an ACL or for any existing UFS file or directory by using the setfacl -m command. Arguments to the setfacl -m command use the same syntax and structure as arguments to the setfacl -s command.

Because each file already has a default owner, group, other, and mask setting, you can use the setfacl -m command on any UFS file without first using the setfacl -s command to specify an owner, group, other, or mask setting. If the file already has the permissions you want to use, you can simply use the setfacl -m command to modify (and create) the ACL for any file or directory.

When you use the -m option, if an entry already exists for a specified UID or GID, the permissions you specify replace the current permissions. If an entry does not exist, it is created.

Type the following syntax to add and modify permissions for a file or files and press Return:

setfacl -m <acl_entry_list><filename1> [<filename2>] [<filename3>]

In the following example, permissions for user ray are modified from rwx to rw- for the file foo.

castle% setfacl -m u:ray:rw- foo
castle% getfacl foo

# file: foo
# owner: winsor
# group: staff
user::rw-
user:ray:rw-         #effective:rw-
group::rw-           #effective:rw-
mask:rw-
other:rw-
castle%

Deleting an ACL Entry

Use the setfacl -d command to delete an ACL entry. To delete the entry, you can specify the entry type and the UID or GID. You do not need to include the permissions as part of the argument to the -d option.

Type the following syntax to delete an ACL entry and then press Return:

setfacl -d<entry_type>:<UID> | <GID> <filename1> [<filename2>] [<filename3>]

In the following example, user ray is deleted from the ACL of the file foo.

castle% setfacl -d u:ray foo
castle% getfacl
usage: getfacl [-ad] file ...
castle% getfacl foo

# file: foo
# owner: winsor
# group: staff
user::rw-
group::rw-           #effective:rw-
mask:rw-
other:rw-
castle%

Copying ACL File Permissions

You can copy ACL file permissions from one file to another without specifying them on the command line by piping the output of getfacl <filename> to another file by typing the following syntax and pressing Return:

getfacl <filename1> | setfacl -f - <filename2>

In the following example, the ACL for file foo is used as the template for the ACL for file bar.

First, verify that the files have different ACL permissions:

castle% getfacl foo bar

# file: foo
# owner: winsor
# group: staff
user::rw-
user:ray:rwx         #effective:rw-
group::rw-          #effective:rw-
mask:rw-
other:rw-

# file: bar
# owner: winsor
# group: staff
user::rw-
group::rw-           #effective:rw-
mask:rw-
other:rw-

Then list the ACL using the getfacl command and pipe the output to the setfacl -f command. The dash (-) tells the setfacl command to use the output from the file specified for the getfacl command as input to the second file.

castle% getfacl foo | setfacl -f - bar

Finally, use the getfacl command to verify that both files now have the same ACL permissions:

castle% getfacl foo bar

# file: foo
# owner: winsor
# group: staff
user::rw-
user:ray:rwx         #effective:rw-
group::rw-          #effective:rw-
mask:rw-
other:rw-

# file: bar
# owner: winsor
# group: staff
user::rw-
user:ray:rwx         #effective:rw-
group::rw-          #effective:rw-
mask:rw-
other:rw-
castle%

Last modified: February 28, 2008