SETFACL(1) manual page
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setfacl - set file access control lists
setfacl [-bkndRLPvh]
[{-m|-x} acl_spec] [{-M|-X} acl_file] file ...
setfacl --restore=file
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
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
permissions.
The -x (--remove) and -X (--remove-file) options remove ACL enries.
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.
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.)
- -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, and setfacl is run by root, the owner and owning group
of all files are restored as well. 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’.
- --version
- Print the version of setfacl and exit.
- --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.
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 permissions: 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).
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 inclu de the union of all permissions affected by the mask entry. (See
the -n option description).
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
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).
Andreas
Gruenbacher, <a.gruenbacher@bestbits.at>.
Please send your bug reports, suggested
features and comments to the above address.
getfacl(1)
, chmod(1)
,
umask(1)
, acl(5)
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