Python笔记：Python版本升级

最小化安装后更换yum源：
http://mirrors.163.com/.help/CentOS7-Base-163.repo
http://mirrors.163.com/.help/CentOS6-Base-163.repo

1.下载repo文件
yum install wget 
wget http://mirrors.163.com/.help/CentOS6-Base-163.repo

2.备份并替换系统的repo文件
cd /etc/yum.repos.d/
mv CentOS-Base.repo CentOS-Base.repo.bak
mv CentOS6-Base-163.repo CentOS-Base.repo

3.执行yum源更新
yum clean all
yum makecache
yum -y update

4.安装开发工具：
yum groupinstall -y 'development tools'
5.安装python依赖包：
yum install -y zlib-devel bzip2-devel openssl-devel xz-libs ncurses-devel

6.下载python新版本：
到https://www.python.org/ftp/python/ 网站找到新版本的下载链接
wget https://www.python.org/ftp/python/2.7.9/Python-2.7.9.tgz
ca python2.7.9
./configure --prefix=/usr/local
make all && make altinstall
make clean 

make distclean 

编译安装的不需要安装python-devel

7.编译安装完毕。输入下面命令查看版本
#/usr/local/bin/python2.7 –V
建立软连接指向到当前系统默认python命令的bin目录（安装完默认会把/usr/locl/bin添加到PATH环境中）
#ln -s /usr/local/bin/python2.7 /usr/local/bin/python

#/usr/local/bin/python –V
此时查询显示的版本是：2.7.9。可是此时yum不能正常使用，需要修改yum的配置文件。
#vi /usr/bin/yum
把文件头部的#!/usr/bin/python改成#!/usr/bin/python2.6 //改为之前的老版本号保存退出。

8.安装easy_install扩展
#wget https://pypi.python.org/packages/source/s/setuptools/setuptools-18.0.1.tar.gz
wget https://bitbucket.org/pypa/setuptools/raw/bootstrap/ez_setup.py
sudo /usr/local/bin/python2.7 ez_setup.py
sudo /usr/local/bin/easy_install-2.7 pip


9.安装新版本Git(版本过低会报401错误):
git依赖以下包：
$ yum install curl-devel expat-devel gettext-devel openssl-devel zlib-devel perl-ExtUtils-MakeMaker package
$ wget https://codeload.github.com/git/git/zip/master
$ cd git-master
$ make prefix=/usr/local all
$ sudo make prefix=/usr/local install

9.当安装Git报错时：usr/bin/perl Makefile.PL PREFIX='/usr/local/git' INSTALL_BASE='' --localedir='/usr/local/git/share/locale'
Can't locate ExtUtils/MakeMaker.pm in @INC (@INC contains: /usr/local/lib64/perl5 /usr/local/share/perl5 /usr/lib64/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib64/perl5 /usr/share/perl5 .) at Makefile.PL line 3.
BEGIN failed--compilation aborted at Makefile.PL line 3.
make[1]: *** [perl.mak] Error 2
make: *** [perl/perl.mak] Error 2 

yum install perl-ExtUtils-MakeMaker package

10.升级完Python再安装其他包，可能会出现以下错误  
import pycurl
ImportError: pycurl: libcurl link-time ssl backend (nss) is different from compile-time ssl backend (openssl)
解决的方法就是:
pip uninstall pycurl
export PYCURL_SSL_LIBRARY=nss
easy_install pycurl
需要注意的是之前用pip安装的，然后卸载掉以后，一定要用easy_install安装才可以导入成功


11.参考；
https://github.com/h2oai/h2o-2/wiki/Installing-python-2.7-on-centos-6.3.-Follow-this-sequence-exactly-for-centos-machine-only