配置鏡像源的主要作用是優化軟件下載速度、提升系統更新穩定性，并確保軟件包獲取的可靠性
我這里配置阿里云鏡像源
鏡像的具體內容參考此文:
文章鏈接

以防萬一,先備份一下

sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak

然后開始修改

sudo nano /etc/apt/sources.list

將里面原有的加#全部注釋掉

并復制黏貼參考博文里的鏡像內容,我的ubuntu是18.04，對應的鏡像是

deb https://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
deb-src https://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiversedeb https://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
deb-src https://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiversedeb https://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
deb-src https://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse# deb https://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
# deb-src https://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiversedeb https://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse
deb-src https://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse

然后退出保存

測試一下有無生效

#更新軟件列表：
sudo apt update
#檢查軟件源：
apt policy curl

配置成功