在FreeBSD 的jail里安装Ubuntu后，一直没有尝试安装mysql服务器，网上也没有找到相应的文档（这证明要么太难，天底下就没有解决方案；要么太容易，以至于显而易见，所以不需要文档）。
今天终于被迫，要解决这个问题！
首先，在Ubuntu jail里安装mysql server
直接使用apt安装即可：
apt install mysql-server
安装好之后，跟普通Ubuntu系统里不一样，没有自动启动mysql服务（也许这里记错了）
普通Ubuntu系统里，启动mysql服务非常简单，直接执行：
systemctl start mysql
System has not been booted with systemd as init system (PID 1). Can't operate.
Failed to connect to bus: Host is down
报错，使用 systemctl status mysql命令也是报错：
systemctl status mysql
System has not been booted with systemd as init system (PID 1). Can't operate.
Failed to connect to bus: Host is down
系统没有使用 systemd 作为初始化系统（init system）
最终使用如下命令启动服务：
service mysql start
再看看服务器状态：
service mysql status
* /usr/bin/mysqladmin Ver 8.0.39-0ubuntu0.22.04.1 for Linux on x86_64 ((Ubuntu))
Copyright (c) 2000, 2024, Oracle and/or its affiliates.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Server version 8.0.39-0ubuntu0.22.04.1
Protocol version 10
Connection Localhost via UNIX socket
UNIX socket /var/run/mysqld/mysqld.sock
Uptime: 12 min 11 sec
Threads: 2 Questions: 10 Slow queries: 0 Opens: 438 Flush tables: 3 Open tables: 27 Queries per second avg: 0.013
终于在Ubuntu jail里启动mysql服务拉！