setfacl

Updated: May 06, 2022

Set the access control list (ACL) for files or directories

Syntax:

setfacl [-bn] [-m entry[,entry...]] [-M acl_file]
        [-x entry[,entry...]] [-X acl_file] [path ...]

Runs on:

QNX Neutrino

Options:

Note: The options are processed in the order they appear on the command line.
-b
Remove all the extended ACLs from the specified files and directories.
-M acl_file
Merge the entries (see below) given in acl_file into the ACLs of the specified files and directories. If you specify a hyphen (-) for acl_file, setfacl reads the entries, one per line, from standard input until you press CtrlD.
-m entry[,entry...]
Merge the given entries into the ACLs of the specified files and directories.
-n
Don't recalculate the permissions associated with the ACL mask entry.
-X acl_file
Remove the entries given in acl_file from the ACLs of the specified files and directories. If you specify a hyphen (-) for acl_file, setfacl reads the entries, one per line, from standard input until you press CtrlD.
-x entry[,entry...]
Remove the given entries from the ACL of the specified files and directories.
path ...
The file or directory that you want to set the ACL for. If you specify a hyphen (-) or don't specify any paths, setfacl reads them, one per line, from standard input until you press CtrlD.

Description:

The setfacl utility modifies the access control list for files or directories. ACLs extend the traditional permissions as set with chmod, giving you finer control over who has access to what. The classes of permissions are:

For an overview of ACLs, see Access Control Lists (ACLs) in the QNX Neutrino User's Guide.

If you're using the -M or -m option, each entry is in one of the following forms:

Entry type Form
Owner user::permissions
Named user (identified by name or by ID) user:user_name:permissions
Owning group group::permissions
Named group (identified by name or ID) group:group_name:permissions
The upper bound on permissions for the group class. mask::permissions
Others other::permissions

If you wish, you can specify just the first letter of user, group, mask, and other. The permissions are a combination of r (read), w (write), x (execute), and - (no permission). You can put these characters in any order and omit any “no permission” hyphens. If the entry already exists in the ACL, the existing permissions are replaced by the new ones.

If you're using the -X or -x option, the permissions are ignored, and all permissions are removed for the specified mask, named user, or named group. You can't remove the entries for the owner, owning group, or others.

Note:
  • (QNX Neutrino 7.0 or later) ACLs persist across reboots if the acl option for the Power-Safe filesystem (fs-qnx6.so) is set to enable (the default).
  • Changes to an ACL can affect the file permissions (i.e., permissions as could be set by chmod). The changes to the file permissions persist across reboots, no matter the setting of the acl option.

Examples:

Add read-only permission for a specific user:

# setfacl -m user:frank:r my_file
# getfacl my_file
# file: my_file
# owner: mabel
# group: docs
user::rw-
user:frank:r--
group::rw-
mask::rw-
other::r--

Remove the permissions specified in my_acl from a file:

# cat my_acl
user:frank:
# setfacl -X my_acl my_file

Exit status:

0
Success.
> 0
An error occurred.