1.Ubuntu python环境2.x升级3.x+

1.ctrl+shift+t打开控制台终端ternimal

2.输入命令安装python3.5

sudo apt-get install python3.5

输入你的密码后会下载，刚才下载的Python程序被安装在usr/localb/python3.5 中

3.修改默认python环境

第一步：先备份原来的链接（在对系统执行删除之前进行备份是个好的习惯）。在ternimal下输入命令：
　　 sudo cp /usr/bin/python /usr/bin/python_bak 
第二步：删除原来默认指向python2.7版本的链接。在ternimal下输入命令：
　　 sudo rm /usr/bin/python 
第三步：重新指定新的链接给python3.5版本。输入命令：
　　 sudo ln -s /usr/bin/python3.5 /usr/bin/python 
至此，python版本更新已经完成。

1 sudo rm /usr/bin/python
2 sudo ln -s /usr/bin/python2.7 /usr/bin/python

4.安装pip管理工具
# 1. 更新系统包
sudo apt-get update
sudo apt-get upgrade

# 2. 安装Pip
sudo apt-get install python-pip

# 3. 检查 pip 是否安装成功
pip -V
pip 常用命令
查看pip帮助：pip -help
安装新的python包：pip install packageName
卸载python包：pip uninstall packageName
寻找python包：pip search packageName

5.Ubuntu下pip3的安装、升级、卸载

安装

sudo apt-get install python3-pip

升级

sudo pip3 install --upgrade pip

卸载

sudo apt-get remove python3-pip

问题参考解决方法：

1.可能需要修改系统软件源(先备份，清除后重加)

/etc/apt/sources.list

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

2.更新软件源

sudo apt-get update

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

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