apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1 for

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。