Ubuntu系统下apt下载中的问题：unable to locate package；更新Ubuntu系统的软件源

出现“unable  to locate package”的是由于软件源出了问题

解决代码：

使用下面代码对软件园进行更新修复

sudo apt-get update
sudo apt-get upgrade

如果以上命令进行缓慢，可使用Ctrl+c结束命令，进行更换源之后在进行上面的命令

更换源

由于使用国外的下载源，因此在进行update 和upgrade 的过程会进行的十分缓慢，所以可以先更换一下下载源

1：在更新下载源之前可以对其进行备份

sudo cp sources.list sources.list.bak

2：编辑sources.list修改下载源

sudo vim /etc/apt/sources.list

3：删除原内容，粘贴上以下下载源（任选其一）

阿里云：

deb-src http://archive.ubuntu.com/ubuntu xenial main restricted #Added by software-properties
deb http://mirrors.aliyun.com/ubuntu/ xenial main restricted
deb-src http://mirrors.aliyun.com/ubuntu/ xenial main restricted multiverse universe #Added by software-properties
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted multiverse universe #Added by software-properties
deb http://mirrors.aliyun.com/ubuntu/ xenial universe
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates universe
deb http://mirrors.aliyun.com/ubuntu/ xenial multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse #Added by software-properties
deb http://archive.canonical.com/ubuntu xenial partner
deb-src http://archive.canonical.com/ubuntu xenial partner
deb http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted multiverse universe #Added by software-properties
deb http://mirrors.aliyun.com/ubuntu/ xenial-security universe
deb http://mirrors.aliyun.com/ubuntu/ xenial-security multiverse

东北大学：

deb-src http://mirror.neu.edu.cn/ubuntu/ xenial main restricted #Added by software-properties

deb http://mirror.neu.edu.cn/ubuntu/ xenial main restricted

deb-src http://mirror.neu.edu.cn/ubuntu/ xenial restricted multiverse universe #Added by software-properties

deb http://mirror.neu.edu.cn/ubuntu/ xenial-updates main restricted

deb-src http://mirror.neu.edu.cn/ubuntu/ xenial-updates main restricted multiverse universe #Added by software-properties

deb http://mirror.neu.edu.cn/ubuntu/ xenial universe

deb http://mirror.neu.edu.cn/ubuntu/ xenial-updates universe

deb http://mirror.neu.edu.cn/ubuntu/ xenial multiverse

deb http://mirror.neu.edu.cn/ubuntu/ xenial-updates multiverse

deb http://mirror.neu.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse

deb-src http://mirror.neu.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse #Added by software-properties

deb http://archive.canonical.com/ubuntu xenial partner deb-src http://archive.canonical.com/ubuntu xenial partner

deb http://mirror.neu.edu.cn/ubuntu/ xenial-security main restricted

deb-src http://mirror.neu.edu.cn/ubuntu/ xenial-security main restricted multiverse universe #Added by software-properties

deb http://mirror.neu.edu.cn/ubuntu/ xenial-security universe

deb http://mirror.neu.edu.cn/ubuntu/ xenial-security multiverse

清华大学：

deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial main restricted

deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates main restricted

deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial universe

deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates universe

deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial multiverse

deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates multiverse

deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse

deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security main restricted

deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security universe deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security multiverse

再使用以下代码使更新的下载源生效

sudo apt-get update