setfacl Man page

SETFACL(1) Access Control Lists SETFACL(1)

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 com‐
mands, …).

The options -m, and -x expect an ACL on the command line. Multiple ACL
entries are separated by comma characters (`,’). The options -M, and -X
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 permis‐
sions.

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, set‐
facl operates on the file mode permission bits. If the ACL does not fit
completely in the permission bits, setfacl modifies the file mode per‐
mission 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 hap‐
pens).

–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’.

–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 inter‐
preted 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.

The perms field is a combination of characters that indicate the per‐
missions: read (r), write (w), execute (x), execute only if the file is
a directory or already has execute permission for some user (X).
Alternatively, the perms field can be an octal digit (0-7).

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 permis‐
sions 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, own‐
ing 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 inclu de 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, .

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

SEE ALSO

getfacl(1), chmod(1), umask(1), acl(5)

May 2000 ACL File Utilities SETFACL(1)