Ubuntu Apache2重启提示could not reliably determine the

Ubuntu 环境，当apache2重启提示：

* Starting web server apache2   
apache2: Could not reliably determine the server's fully qualified domain name,
... waiting apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1 for ServerName

解决的问题是：

sudo vim /etc/apache2/sites-available/default

打开default文件后，在default文件顶端加入：

ServerName 127.0.0.1

重启apache2 就不会提示上述错误了。