欢迎关注：天际使徒的个人博客

• 问题描述：出现Failed to fetch http://…..
• 问题原因：一般是由于直接使用国外的源无法连接的原因导致的
• 解决方案：直接替换成国内的源即可

                （1）执行备份命令：sudo cp /etc/apt/sources.list /etc/apt/sources.list.old

                （2）打开文件：sudo vim /etc/apt/sources.list

                （3）换源：复制源覆盖文件原来的内容（根据自己的网去尝试，选择最快的一个）

1. 各种ubuntu版本（查看版本命令：cat /etc/issue）的清华源：清华源文件
2. 阿里云源（试用14.04/16.04/18.04）

deb http://mirrors.aliyun.com/ubuntu/ trusty main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ trusty-security main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ trusty-updates main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ trusty-proposed main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ trusty-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ trusty main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-security main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-updates main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-proposed main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-backports main restricted universe multiverse