junjie@ubuntu:/usr/bin$ sudo apache2ctl -k stop
[sudo] password for junjie:
apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1 for ServerName
解决办法:
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。