SETFACL(1)

NAME
setfacl - set ACL information

SYNOPSIS
setfacl [-bdhkn] [-a position entries] [-m entries] [-M file] [-x entries | position] [-X file] [file ...]

DESCRIPTION
The setfacl utility sets discretionary access control information on the specified file(s). If no files are specified, or the list consists of the only ‘-’, the file names are taken from the standard input.

The following options are available:

-a position entries
    Modify the ACL on the specified files by inserting new ACL entries specified in entries, starting at position position, counting from zero. This option is only applicable to NFSv4 ACLs.

-b  Remove all ACL entries except for the three required entries (POSIX.1e ACLs) or six "canonical" entries (NFSv4 ACLs). If the POSIX.1e ACL contains a “mask” entry, the permissions of the “group” entry in the resulting ACL will be set to the permission associated with both the “group” and “mask” entries of the current ACL.

-d  The operations apply to the default ACL entries instead of access ACL entries. Currently only directories may have default ACL's. This option is not applicable to NFSv4 ACLs.

-h  If the target of the operation is a symbolic link, perform the operation on the symbolic link itself, rather than following the link.

-k  Delete any default ACL entries on the specified files. It is not considered an error if the specified files do not have any default ACL entries. An error will be reported if any of the specified files cannot have a default entry (i.e. non-directories). This option is not applicable to NFSv4 ACLs.

-m entries
    Modify the ACL on the specified file. New entries will be added, and existing entries will be modified according to the entries argument. For NFSv4 ACLs, it is recommended to use the -a and -x options instead.

-M file
    Modify the ACL entries on the specified files by adding new ACL entries and modifying existing ACL entries with the ACL entries specified in the file file. If file is -, the input is taken from stdin.

-n  Do not recalculate the permissions associated with the ACL mask entry. This option is not applicable to NFSv4 ACLs.

-x entries | position
    If entries is specified, remove the ACL entries specified there from the access or default ACL of the specified files. Otherwise, remove entry at index position, counting from zero.

-X file
    Remove the ACL entries specified in the file file from the access or default ACL of the specified files.

The above options are evaluated in the order specified on the command-line.

POSIX.1e ACL ENTRIES
A POSIX.1E ACL entry contains three colon-separated fields: an ACL tag, an ACL qualifier, and discretionary access permissions:

ACL tag
    The ACL tag specifies the ACL entry type and consists of one of the following: “user” or ‘u’ specifying the access granted to the owner of the file or a specified user; “group” or ‘g’ specifying the access granted to the file owning group or a specified group; “other” or ‘o’ specifying the access granted to any process that does not match any user or group ACL entry; “mask” or ‘m’ specifying the maximum access granted to any ACL entry except the “user” ACL entry for the file owner and the “other” ACL entry.

ACL qualifier
    The ACL qualifier field describes the user or group associated with the ACL entry. It may consist of one of the following: uid or user name, gid or group name, or empty. For “user” ACL entries, an empty field specifies access granted to the file owner. For “group” ACL entries, an empty field specifies access granted to the file owning group. “mask” and “other” ACL entries do not use this field.

access permissions
    The access permissions field contains up to one of each of the following: ‘r’, ‘w’, and ‘x’ to set read, write, and execute permissions, respectively. Each of these may be excluded or replaced with a ‘-’ character to indicate no access.

A “mask” ACL entry is required on a file with any ACL entries other than the default “user”, “group”, and “other” ACL entries. If the -n option is not specified and no “mask” ACL entry was specified, the setfacl utility will apply a “mask” ACL entry consisting of the union of the permissions associated with all “group” ACL entries in the resulting ACL.

Traditional POSIX interfaces acting on file system object modes have modified semantics in the presence of POSIX.1e extended ACLs. When a mask entry is present on the access ACL of an object, the mask entry is substituted for the group bits; this occurs in programs such as stat(1) or ls(1). When the mode is modified on an object that has a mask entry, the changes applied to the group bits will actually be applied to the mask entry. These semantics provide for greater application compatibility: applications modifying the mode instead of the ACL will see conservative behavior, limiting the effective rights granted by all of the additional user and group entries; this occurs in programs such as chmod(1).

ACL entries applied from a file using the -M or -X options shall be of the following form: one ACL entry per line, as previously specified; whitespace is ignored; any text after a ‘#’ is ignored (comments).

When POSIX.1e ACL entries are evaluated, the access check algorithm checks the ACL entries in the following order: file owner, “user” ACL entries, file owning group, “group” ACL entries, and “other” ACL entry.

Multiple ACL entries specified on the command line are separated by commas.

It is possible for files and directories to inherit ACL entries from their parent directory. This is accomplished through the use of the default ACL. It should be noted that before you can specify a default ACL, the mandatory ACL entries for user, group, other and mask must be set. For more details see the examples below. Default ACLs can be created by using -d.

NFSv4 ACL ENTRIES
An NFSv4 ACL entry contains four or five colon-separated fields: an ACL tag, an ACL qualifier (only for “user” and “group” tags), discretionary access permissions, ACL inheritance flags, and ACL type:

ACL tag
    The ACL tag specifies the ACL entry type and consists of one of the following: “user” or ‘u’ specifying the access granted to the specified user; “group” or ‘g’ specifying the access granted to the specified group; “owner@” specifying the access granted to the owner of the file; “group@” specifying the access granted to the file owning group; “everyone@” specifying everyone. Note that “everyone@” is not the same as traditional Unix “other” - it means, literally, everyone, including file owner and owning group.

ACL qualifier
    The ACL qualifier field describes the user or group associated with the ACL entry. It may consist of one of the following: uid or user name, or gid or group name. In entries whose tag type is one of “owner@”, “group@”, or “everyone@”, this field is omitted altogether, including the trailing comma.

access permissions
    Access permissions may be specified in either short or long form. Short and long forms may not be mixed. Permissions in long form are separated by the ‘/’ character; in short form, they are concatenated together. Valid permissions are:

    Short
        Long

    r   read_data

    w   write_data

    x   execute

    p   append_data

    D   delete_child

    d   delete

    a   read_attributes

    A   write_attributes

    R   read_xattr

    W   write_xattr

    c   read_acl

    C   write_acl

    o   write_owner

    s   synchronize

    In addition, the following permission sets may be used:

    Set Permissions

    full_set
        all permissions, as shown above

    modify_set
        all permissions except write_acl and write_owner

    read_set
        read_data, read_attributes, read_xattr and read_acl

    write_set
        write_data, append_data, write_attributes and write_xattr

ACL inheritance flags
    Inheritance flags may be specified in either short or long form. Short and long forms may not be mixed. Access flags in long form are separated by the ‘/’ character; in short form, they are concatenated together. Valid inheritance flags are:

    Short
        Long

    f   file_inherit

    d   dir_inherit

    i   inherit_only

    n   no_propagate

    I   inherited

    Other than the "inherited" flag, inheritance flags may be only set on directories.

ACL type
    The ACL type field is either “allow” or “deny”.

ACL entries applied from a file using the -M or -X options shall be of the following form: one ACL entry per line, as previously specified; whitespace is ignored; any text after a ‘#’ is ignored (comments).

NFSv4 ACL entries are evaluated in their visible order.

Multiple ACL entries specified on the command line are separated by commas.

Note that the file owner is always granted the read_acl, write_acl, read_attributes, and write_attributes permissions, even if the ACL would deny it.

EXIT STATUS

EXAMPLES
    setfacl -d -m u::rwx,g::rx,o::rx,mask::rwx dir
    setfacl -d -m g:admins:rwx dir

The first command sets the mandatory elements of the POSIX.1e default ACL. The second command specifies that users in group admins can have read, write, and execute permissions for directory named "dir". It should be noted that any files or directories created underneath "dir" will inherit these default ACLs upon creation.

    setfacl -m u::rwx,g:mail:rw file

Sets read, write, and execute permissions for the file owner's POSIX.1e ACL entry and read and write permissions for group mail on file.

    setfacl -m owner@:rwxp::allow,g:mail:rwp::allow file

Semantically equal to the example above, but for NFSv4 ACL.

    setfacl -M file1 file2

Sets/updates the ACL entries contained in file1 on file2.

    setfacl -x g:mail:rw file

Remove the group mail POSIX.1e ACL entry containing read/write permissions from file.

    setfacl -x0 file

Remove the first entry from the NFSv4 ACL from file.

    setfacl -bn file

Remove all “access” ACL entries except for the three required from file.

    getfacl file1 | setfacl -b -n -M - file2

Copy ACL entries from file1 to file2.

SEE ALSO
getfacl(1), acl(3), getextattr(8), setextattr(8), acl(9), extattr(9)

STANDARDS
The setfacl utility is expected to be IEEE Std 1003.2c compliant.

HISTORY
Extended Attribute and Access Control List support was developed as part of the TrustedBSD Project and introduced in FreeBSD 5.0. NFSv4 ACL support was introduced in FreeBSD 8.1.

AUTHORS
-nosplit The setfacl utility was written by Chris D. Faulhaber <jedgar@fxp.org>. NFSv4 ACL support was implemented by Edward Tomasz Napierala <trasz@FreeBSD.org>.