"ls -lah" 输出中权限末尾的点是什么意思？

Question

我找到了一些 Linux 文件，当我输入 ls -lah 时，它会输出以下权限格式：

... 
drwxr-xr-x.  2 root    root  
...
-rw-rw-r--.  1 root    root 
...

我想知道，权限格式末尾的点（-rw-rw-r--.）是什么意思？

Answer 1

来自 GNU.org 在 what information is listed 下：

GNU ls uses a ‘.’ character to indicate a file with a SELinux security context, but no other alternate access method.

这基本上意味着该文件有一个 Access Control List (ACL) with SELinux. You can set or delete ACL association for a file by using the setfacl 命令

Answer 2

根据 Filesystem permissions wiki page，点表示存在 SELinux 上下文。

Answer 3

来自 info coreutils 'ls invocation' Linux

GNU `ls' uses a `.' character to indicate a file with an SELinux
     security context, but no other alternate access method.

A file with any other combination of alternate access methods is
     marked with a `+' character.

Answer 4

所以不是 ACL，来自@Tom van der Lee 参考资料

+ (plus) suffix indicates an access control list that can control additional permissions.
. (dot) suffix indicates an SELinux context is present. Details may be listed with the command ls -Z.
@ suffix indicates extended file attributes are present.

我机器上的一个例子：

$ ls -l 35mm DNS-cache 
-rw-r--r--. 1 graeme graeme     60 Feb 27  2010 35mm
-rw-r--r--  1 graeme everyone 5193 Jun  1 14:45 DNS-cache
$ 
$ getfacl -s 35mm DNS-cache 
$ ls -Z  35mm DNS-cache 
unconfined_u:object_r:user_home_t:s0 35mm
                                   ? DNS-cache

所以 getfacl -s 没有产生任何输出，因为没有 ACL。但是有一个安全上下文（见 ls -Z）

"ls -lah" 输出中权限末尾的点是什么意思？

What does the dot at the end of the permissions in the output of "ls -lah" mean?

ls

file-attributes

xattr