Ubuntu Manpage: setfacl - set file access control lists

NAME

       setfacl - set file access control lists

SYNOPSIS

       setfacl [-bkndRLPvh] [{-m|-x} acl_spec] [{-M|-X} acl_file] file ...

       setfacl --restore={file|-}

DESCRIPTION

This utility sets Access Control Lists (ACLs) of files and directories. On the command
line, a sequence of commands is followed by a sequence of files (which in turn can be
followed by another sequence of commands, ...).

The -m and -x options expect an ACL on the command line. Multiple ACL entries are
separated by comma characters (`,'). The -M and -X options read an ACL from a file or from
standard input. The ACL entry format is described in Section ACL ENTRIES.

The --set and --set-file options set the ACL of a file or a directory. The previous ACL is
replaced. ACL entries for this operation must include permissions.

The -m (--modify) and -M (--modify-file) options modify the ACL of a file or directory.
ACL entries for this operation must include permissions.

The -x (--remove) and -X (--remove-file) options remove ACL entries. It is not an error to
remove an entry which does not exist. Only ACL entries without the perms field are
accepted as parameters, unless POSIXLY_CORRECT is defined.

When reading from files using the -M and -X options, setfacl accepts the output getfacl
produces. There is at most one ACL entry per line. After a Pound sign (`#'), everything
up to the end of the line is treated as a comment.

If setfacl is used on a file system which does not support ACLs, setfacl operates on the
file mode permission bits. If the ACL does not fit completely in the permission bits,
setfacl modifies the file mode permission bits to reflect the ACL as closely as possible,
writes an error message to standard error, and returns with an exit status greater than 0.

PERMISSIONS
The file owner and processes capable of CAP_FOWNER are granted the right to modify ACLs of
a file. This is analogous to the permissions required for accessing the file mode. (On
current Linux systems, root is the only user with the CAP_FOWNER capability.)

OPTIONS

-b, --remove-all
Remove all extended ACL entries. The base ACL entries of the owner, group and others
are retained.

-k, --remove-default
Remove the Default ACL. If no Default ACL exists, no warnings are issued.

-n, --no-mask
Do not recalculate the effective rights mask. The default behavior of setfacl is to
recalculate the ACL mask entry, unless a mask entry was explicitly given. The mask
entry is set to the union of all permissions of the owning group, and all named user
and group entries. (These are exactly the entries affected by the mask entry).

--mask
Do recalculate the effective rights mask, even if an ACL mask entry was explicitly
given. (See the -n option.)

-d, --default
All operations apply to the Default ACL. Regular ACL entries in the input set are
promoted to Default ACL entries. Default ACL entries in the input set are discarded.
(A warning is issued if that happens).

--restore={file|-}
Restore a permission backup created by `getfacl -R' or similar. All permissions of a
complete directory subtree are restored using this mechanism. If the input contains
owner comments or group comments, setfacl attempts to restore the owner and owning
group. If the input contains flags comments (which define the setuid, setgid, and
sticky bits), setfacl sets those three bits accordingly; otherwise, it clears them.
This option cannot be mixed with other options except `--test'. If the file specified
is '-', then it will be read from standard input.

--test
Test mode. Instead of changing the ACLs of any files, the resulting ACLs are listed.

-R, --recursive
Apply operations to all files and directories recursively. This option cannot be mixed
with `--restore'.

-L, --logical
Logical walk, follow symbolic links to directories. The default behavior is to follow
symbolic link arguments, and skip symbolic links encountered in subdirectories. Only
effective in combination with -R. This option cannot be mixed with `--restore'.

-P, --physical
Physical walk, do not follow symbolic links to directories. This also skips symbolic
link arguments. Only effective in combination with -R. This option cannot be mixed
with `--restore'.

-v, --version
Print the version of setfacl and exit.

-h, --help
Print help explaining the command line options.

-- End of command line options. All remaining parameters are interpreted as file names,
even if they start with a dash.

- If the file name parameter is a single dash, setfacl reads a list of files from
standard input.

ACL ENTRIES
The setfacl utility recognizes the following ACL entry formats (blanks inserted for
clarity):

[d[efault]:] [u[ser]:]uid [:perms]
Permissions of a named user. Permissions of the file owner if uid is empty.

[d[efault]:] g[roup]:gid [:perms]
Permissions of a named group. Permissions of the owning group if gid is empty.

[d[efault]:] m[ask][:] [:perms]
Effective rights mask

[d[efault]:] o[ther][:] [:perms]
Permissions of others.

Whitespace between delimiter characters and non-delimiter characters is ignored.

Proper ACL entries including permissions are used in modify and set operations. (options
-m, -M, --set and --set-file). Entries without the perms field are used for deletion of
entries (options -x and -X).

For uid and gid you can specify either a name or a number. Character literals may be
specified with a backslash followed by the 3-digit octal digits corresponding to the ASCII
code for the character (e.g., \101 for 'A'). If the name contains a literal backslash
followed by 3 digits, the backslash must be escaped (i.e., \\).

The perms field is a combination of characters that indicate the read (r), write (w),
execute (x) permissions. Dash characters in the perms field (-) are ignored. The
character X stands for the execute permission if the file is a directory or already has
execute permission for some user. Alternatively, the perms field can define the
permissions numerically, as a bit-wise combination of read (4), write (2), and execute
(1). Zero perms fields or perms fields that only consist of dashes indicate no
permissions.

AUTOMATICALLY CREATED ENTRIES
Initially, files and directories contain only the three base ACL entries for the owner,
the group, and others. There are some rules that need to be satisfied in order for an ACL
to be valid:

* The three base entries cannot be removed. There must be exactly one entry of each of
these base entry types.

* Whenever an ACL contains named user entries or named group objects, it must also
contain an effective rights mask.

* Whenever an ACL contains any Default ACL entries, the three Default ACL base entries
(default owner, default group, and default others) must also exist.

* Whenever a Default ACL contains named user entries or named group objects, it must
also contain a default effective rights mask.

To help the user ensure these rules, setfacl creates entries from existing entries under
the following conditions:

* If an ACL contains named user or named group entries, and no mask entry exists, a mask
entry containing the same permissions as the group entry is created. Unless the -n
option is given, the permissions of the mask entry are further adjusted to include the
union of all permissions affected by the mask entry. (See the -n option description).

* If a Default ACL entry is created, and the Default ACL contains no owner, owning
group, or others entry, a copy of the ACL owner, owning group, or others entry is
added to the Default ACL.

* If a Default ACL contains named user entries or named group entries, and no mask entry
exists, a mask entry containing the same permissions as the default Default ACL's
group entry is added. Unless the -n option is given, the permissions of the mask entry
are further adjusted to include the union of all permissions affected by the mask
entry. (See the -n option description).

EXAMPLES

       Granting an additional user read access
              setfacl -m u:lisa:r file

       Revoking write access from all groups and all named  users  (using  the  effective  rights
       mask)
              setfacl -m m::rx file

       Removing a named group entry from a file's ACL
              setfacl -x g:staff file

       Copying the ACL of one file to another
              getfacl file1 | setfacl --set-file=- file2

       Copying the access ACL into the Default ACL
              getfacl --access dir | setfacl -d -M- dir

CONFORMANCE TO POSIX 1003.1e DRAFT STANDARD 17

       If  the  environment  variable POSIXLY_CORRECT is defined, the default behavior of setfacl
       changes as follows: All non-standard options are disabled.   The  ``default:''  prefix  is
       disabled.  The -x and -X options also accept permission fields (and ignore them).

AUTHOR

       Andreas Gruenbacher, <andreas.gruenbacher@gmail.com>.

       Please send your bug reports, suggested features and comments to the above address.