setfacl
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 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, 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,
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. The default behavior is to
follow symbolic link arguments, and to skip symbolic links encoun-
tered in subdirectories. This option cannot be mixed with
‘--restore’.
-P, --physical
Physical walk, skip all symbolic links. This also skips symbolic
link arguments. 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 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, <a.gruenbacher@bestbits.at>.
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)
configuring access control lists(ACLs)
基本内容：
描述ACLs
在命令行下使用ACLs
在图像界面下使用ACLs
创建默认的ACLs
当为一个文件或目录的ACL被创建了之后，他就提供了更广泛的针对文件或目录的访问许可.这些许可是在基于UNIX许可情况下的一种延伸.标准的UNIX文件对于文件所有者,文件组,其他组具有读写执行三种权限.
ACLs提供了针对每个文件或每个目录的更广泛的访问控制.
ACL的语法格式是：
entry-type：[UID OR GID]:perm.其中perm代表一些执行权限如读，写，执行，或由0-7的数字来代表
ACL entry type有下面几种：
1,u[ser]::perm
2,g[roup]::perm
3,o[ther]::perm
4,u[ser]::UID:perm or u[ser]:username:perm
5,g[roup]:GID:perm or g[roup]:groupname:perm
6,m[ask]::perm
介绍和ACL相关的一些命令：
getfacl filename(s):展示文件上的ACL
setfacl -m acl_entries filename:在文件上创建或更改ACL
setfacl -s acl_entries filename:用新的ACL代替旧的ACL
setfacl -d acl_entries filename:删除文件上一个或多个ACL
setfacl -f acl_file filename
setfacl -r filename:重新计算ACL mask.
能通过两种方式即命令行下或图像界面(使用命令/usr/dt/bin/dtfile启动图像界面)，来做下面一些事情：
判断文件是否有一个ACL，列出、更改、删除、替换一个ACL，重新计算ACL的mask，从一个文件拷贝一个ACL链接
1,判断文件是否有一个ACL，常用的方法是进入到相应的目录，用ls -l命令展开,如果在权限后带一个加号,说明有ACL.不过用ls命令得不到实际的ACL，推荐用getfacl命令.
2,列出一个ACL,常用的命令格式是：getfacl [-a | -d] filename1 [filename2...]
-a列出了文件名，文件所有者，文件所属组，ACL条目
-d列出了文件名，文件所有者，文件所属组，及默认的ACL条目
要注意一点这里的ACL mask跟umask不相同，umask值是默认的文件或目录拥有的权限.而ACL mask对每个文件或目录能不相同.
3,更改一个ACL，这也是常用的方法.常用的格式是：setfacl -m acl_entry,filename
比如:# setfacl -m u:userb:7 file2
4,删除一个ACL,常用的命令格式是:setfacl -d acl_entry filename
比如:# setfacl -d u:usera file2
5,替换一个ACL,常用的命令格式是:setfacl -s u::perm,g::perm,o:perm,m:perm,[u:UID:perm],[g:GID:perm] filename
比如:# setfacl -s u::rwx,g::rw-,o:r--,m;rw-,u:usera:rwx file1
6,更改ACL mask.
常用的命令格式是:setfacl -r -m acl_entry filename.其中-r选项是指接受最大的effictive值.-m是更改当前的ACL
比如:# setfacl -r -m u:usera:7 file1
7,复制一个文件的ACL到另一个文件.常用的命令格式是:getfacl filename1 |setfacl -f - filename2
8,创建默认的ACL.要注意的是设置默认的ACL只针对目录操作，而且在为一个新增的用户或组之前必须设置默认的user,group,other,ACL mask值.
比如:#setfacl -m d:u::rwx,d:g::r-x,d:o:r-x,d:m:r-x dir1，其中d代表default.
设置了这个之后，才能够添加新的用户，比如:# setfacl -m default:user:usera:rwx dir1
