原文：https://pip.pypa.io/en/stable/installing/
今天搜到了一个更简单的方法，记录如下：
步骤1，下载一个安装脚本：
[root@bogon ~]# wget https://bootstrap.pypa.io/get-pip.py
--2018-07-11 02:09:30-- https://bootstrap.pypa.io/get-pip.py
Resolving bootstrap.pypa.io (bootstrap.pypa.io)... 151.101.76.175, 2a04:4e42:12::175
Connecting to bootstrap.pypa.io (bootstrap.pypa.io)|151.101.76.175|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 1642329 (1.6M) [text/x-python]
Saving to: ‘get-pip.py’
100%[==============================================================================>] 1,642,329 122KB/s in 14s
2018-07-11 02:09:46 (113 KB/s) - ‘get-pip.py’ saved [1642329/1642329]
步骤2，执行安装过程
[root@bogon ~]# python get-pip.py
Collecting pip
Downloading https://files.pythonhosted.org/packages/0f/74/ecd13431bcc456ed390b44c8a6e917c1820365cbebcb6a8974d1cd045ab4/pip-10.0.1-py2.py3-none-any.whl (1.3MB)
100% |████████████████████████████████| 1.3MB 91kB/s
Collecting setuptools
Downloading https://files.pythonhosted.org/packages/ff/f4/385715ccc461885f3cedf57a41ae3c12b5fec3f35cce4c8706b1a112a133/setuptools-40.0.0-py2.py3-none-any.whl (567kB)
100% |████████████████████████████████| 573kB 62kB/s
Collecting wheel
Downloading https://files.pythonhosted.org/packages/81/30/e935244ca6165187ae8be876b6316ae201b71485538ffac1d718843025a9/wheel-0.31.1-py2.py3-none-any.whl (41kB)
100% |████████████████████████████████| 51kB 89kB/s
Installing collected packages: pip, setuptools, wheel
Successfully installed pip-10.0.1 setuptools-40.0.0 wheel-0.31.1至此安装成功。
上面安装过程中，同时安装了setuptools和wheel，可以通过下面两个参数跳过安装：
--no-setuptools
--no-wheel