centos 7.3 升级 python 到 2.7.13 以及pip yum

更新python千万不要把老版本的删除！新老版本是能够共存的，不少基本的命令、 
软件包都要依赖预装的老版本python的，好比yum。

1. 查看 python 版本
[jack@ ~]$ python -V 
Python 2.7.5

2.编译前准备
python 在编译以前配置的时候会探测环境的库是否存在，有的库不在，对应的功能会放弃

为了安装setuptools，要须要安装zlib：

yum install zlib zlib-dev 
为在python编译时加入ssl模块，yum安装openssl和openssl-devel:

yum install openssl

yum install openssl-devel

209 sudo yum install openssl 
210 sudo yum install openssl-devel 
211 sudo yum install ncurses-libs 
212 sudo yum install readline-devel 
213 sudo yum install sqlite-devel 
214 sudo yum install bzip2-devel 
215 sudo yum install gdbm-devel 
216 sudo yum install libdbi-devel

2.编译python 2.7.13
cd /home/jack/work/
wget https://www.python.org/ftp/python/2.7.13/Python-2.7.13.tgz
tar xvf Python-2.7.13.tgz
cd Python-2.7.13
./configure --prefix=/usr/local/python27
sudo make
sudo make install
3 . 本来的链接

4. 修改链接
sudo mv /usr/bin/python2 /usr/bin/python2_old
sudo mv /usr/bin/python2.7 /usr/bin/python2.7.5
sudo mv /usr/bin/python /usr/bin/python_old

sudo ln -s /usr/local/python27/bin/python2.7 /usr/bin/python2
sudo ln -s /usr/bin/python2 /usr/bin/python

其中用到了 python2 的目的是 ，之后有可能会用到python3 
/usr/bin/python2 和 /usr/bin/python2.7 应该须要删掉 
由于有的python 脚本里面会注明使用 /usr/bin/python2

5. 解决 yum的问题
yum 须要用到原来的 python2.7.5

sudo vi /usr/bin/yum

sudo vi /usr/libexec/urlgrabber-ext-down

6 测试一下 yum 是否可以正常使用
yum info gcc

查找和显示 
yum info package1 显示安装包信息package1 
yum list 显示全部已经安装和能够安装的程序包 
yum list package1 显示指定程序包安装状况package1 
yum groupinfo group1 显示程序组group1信息yum search string 根据关键字string查找安装包

7 安装python2.7.13 对应的pip
wget https://bootstrap.pypa.io/get-pip.py

sudo python get-pip.py

The script wheel is installed in ‘/usr/local/python27/bin’ which is not on PATH. 
Consider adding this directory to PATH or, if you prefer to suppress this warning, use –no-warn-script-location.

8 替换原来的pip
原来的pip 

sudo mv /usr/bin/pip /usr/bin/pip_old 
sudo mv /usr/bin/pip2 /usr/bin/pip2_old 
sudo mv /usr/bin/pip2.7 /usr/bin/pip2.7_old

sudo cp /usr/local/python27/bin/pip* /usr/bin/

9 测试一下 pip

10 设置环境变量
sudo vi /etc/profile 
在最后面加上

export PYTHON_HOME=/usr/local/python27
export PATH=$PYTHON_HOME/bin:$PATH

source /etc/profile # 当前终端生效，reboot后才会彻底生效 
echo $PATH

遇到问题：
Python build finished, but the necessary bits to build these modules were not found: 
_bsddb _curses _curses_panel 
_sqlite3 _ssl _tkinter 
bsddb185 bz2 dbm 
dl gdbm imageop 
readline sunaudiodev 
To find the necessary bits, look in setup.py in detect_modules() for the module’s name.

running build_scripts

 
209 sudo yum install openssl 
210 sudo yum install openssl-devel 
211 sudo yum install ncurses-libs 
212 sudo yum install readline-devel 
213 sudo yum install sqlite-devel 
214 sudo yum install bzip2-devel 
215 sudo yum install gdbm-devel 
216 sudo yum install libdbi-devel

遇到问题
Traceback (most recent call last): 
File “get-pip.py”, line 20649, in 
main() 
File “get-pip.py”, line 197, in main 
bootstrap(tmpdir=tmpdir) 
File “get-pip.py”, line 82, in bootstrap 
import pip._internal 
zipimport.ZipImportError: can’t decompress data; zlib not available

yum install zlib zlib-devel -y  yum -y install zlib*