运行
sudo /etc/init.d/apach2 restart
后，提示警告信息：
apache2:Could not reliably determine the server's fully qualified domain name,using 127.0.1.1 for ServerName
...waiting apache2:Could not reliably determine the server's qualified domain nama ,using 127.0.1.1 for ServerName
解决办法：
sudo vi /etc/apache2/sites-available/default
在顶部加上ServerName 127.0.0.1
重启即可