轉載自：https://blog.csdn.net/qq_35451572/article/details/79516563
Ubuntu系統自帶的源都是國外的網址，國內用戶在使用的時候網速比較慢。一個軟件的下載是十分痛苦的，這里講解一下如何將國外源更換為國內源，讓你的網速Biu.Biu.Biu
1.備份原來的源
sudo cp /etc/apt/sources.list /etc/apt/sources_init.list
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將以前的源備份一下，以防以后可以用的。
2.更換源
sudo gedit /etc/apt/sources.list
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使用gedit打開文檔，將下邊的阿里源復制進去，然后點擊保存關閉。
阿里源
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
3.更新
更新源
sudo apt-get update
復損壞的軟件包，嘗試卸載出錯的包，重新安裝正確版本的。
sudo apt-get -f install
更新軟件
sudo apt-get upgrade