“无法找到包python-pip”当尝试从新鲜的18.04安装时安装

我在网上关注python的教程,它让我这样做:

akclark@enceladus:~$ pip install virtualenv 

但是我得到了以下内容:

 Command 'pip' not found, but can be installed with: sudo apt install python-pip 

够容易吧? 所以我试试..

 akclark@enceladus:~$ sudo apt install python-pip 

但我得到一个错误……

 Reading package lists... Done Building dependency tree Reading state information... Done E: Unable to locate package python-pip 

我究竟做错了什么?

编辑:每个评论我已经尝试过sudo apt update

EDIT2:我尝试了apt-cache madison python-pip并得到了

 N: Unable to locate package python-pip 

EDIT3: grep '^deb ' /etc/apt/sources.list etc/apt/sources.list显示

 deb http://archive.ubuntu.com/ubuntu bionic main deb http://archive.ubuntu.com/ubuntu bionic-security main deb http://archive.ubuntu.com/ubuntu bionic-updates main 

您必须启用包含python-pip包的universe类别。

使用编辑器打开/etc/apt/sources.list ,例如nano

 sudo nano /etc/apt/sources.list 

然后在每行的末尾添加universe ,如下所示:

 deb http://archive.ubuntu.com/ubuntu bionic main universe deb http://archive.ubuntu.com/ubuntu bionic-security main universe deb http://archive.ubuntu.com/ubuntu bionic-updates main universe 

Ctrl + O保存文件。

然后运行:

 sudo apt update 

最后:

 sudo apt install python-pip