Modify apt-get source to domestic mirror source

# backupcp /etc/apt/sources.list /etc/apt/sources.list.baksudo vim /etc/apt/sources.list

# Ali Mirrordeb http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiversedeb http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiversedeb http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiversedeb http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiversedeb http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiversedeb-src http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiversedeb-src http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiversedeb-src http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiversedeb-src http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiversedeb-src http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse# University of Science and Technology of Chinadeb http://mirrors.ustc.edu.cn/ubuntu/precise-updates main restricteddeb-src http://mirrors.ustc.edu.cn/ubuntu/precise-updates main restricteddeb http://mirrors.ustc.edu.cn/ubuntu/ precise universedeb-src http://mirrors.ustc.edu.cn/ubuntu/ precise universedeb http://mirrors.ustc.edu.cn/ubuntu/precise-updates universedeb-src http://mirrors.ustc.edu.cn/ubuntu/precise-updates universedeb http://mirrors.ustc.edu.cn/ubuntu/precise multiversedeb-src http://mirrors.ustc.edu.cn/ubuntu/precise multiversedeb http://mirrors.ustc.edu.cn/ubuntu/precise-updates multiversedeb-src http://mirrors.ustc.edu.cn/ubuntu/precise-updates multiversedeb http://mirrors.ustc.edu.cn/ubuntu/ precise-backports main restricted universe multiversedeb-src http://mirrors.ustc.edu.cn/ubuntu/ precise-backports main restricted universe multiverse# Sohu Sourcedeb http://mirrors.sohu.com/ubuntu/ precise-updates main restricteddeb-src http://mirrors.sohu.com/ubuntu/ precise-updates main restricteddeb http://mirrors.sohu.com/ubuntu/ precise universedeb-src http://mirrors.sohu.com/ubuntu/ precise universedeb http://mirrors.sohu.com/ubuntu/ precise-updates universedeb-src http://mirrors.sohu.com/ubuntu/ precise-updates universedeb http://mirrors.sohu.com/ubuntu/precise multiversedeb-src http://mirrors.sohu.com/ubuntu/precise multiversedeb http://mirrors.sohu.com/ubuntu/precise-updates multiversedeb-src http://mirrors.sohu.com/ubuntu/precise-updates multiversedeb http://mirrors.sohu.com/ubuntu/ precise-backports main restricted universe multiversedeb-src http://mirrors.sohu.com/ubuntu/ precise-backports main restricted universe multiverse# Netease sourcedeb http://mirrors.163.com/ubuntu/ precise-updates main restricteddeb-src http://mirrors.163.com/ubuntu/precise-updates main restricteddeb http://mirrors.163.com/ubuntu/ precise universedeb-src http://mirrors.163.com/ubuntu/ precise universedeb http://mirrors.163.com/ubuntu/precise-updates universedeb-src http://mirrors.163.com/ubuntu/precise-updates universedeb http://mirrors.163.com/ubuntu/precise multiversedeb-src http://mirrors.163.com/ubuntu/precise multiversedeb http://mirrors.163.com/ubuntu/precise-updates multiversedeb-src http://mirrors.163.com/ubuntu/precise-updates multiversedeb http://mirrors.163.com/ubuntu/ precise-backports main restricted universe multiversedeb-src http://mirrors.163.com/ubuntu/ precise-backports main restricted universe multiverse

apt-get updateapt updatesudo apt-get updatesudo apt-get upgrade