setfacl/getfacl 命令没有在我的服务器上运行，它说：
The program 'setfacl' is currently not installed. You can install it by typing:
sudo apt-get install acl
当我尝试安装它时，它说：
sudo apt-get install acl
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package acl is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
E: Package 'acl' has no installation candidate
我将以下源行添加到 apt 配置源列表中：
然后我可以正常安装acl。