在CentOS 6.x上，默认自带的Python是2.6.x版本，这个版本的Python有点老了，比如“collections.OrderedDict”就是2.7才有的，而且著名的Python Web框架Django的新版（如：1.7）就不支持Python2.6，最低要求是2.7了。而一些公司或者共有云上的服务器就是使用CentOS6.x，所以也就有了升级Python到2.7的需求。
升级Python之前，需要先安装一些工具和软件库，否则后面安装Python或pip时可能出错。Python2.7通过源码安装，python可行执行程序默认是安装在/usr/local/bin/，一般来在$PATH中，/usr/local/bin是优先使用的（如果不是，需要自己设置一下PATH环境变量）。在安装完python后，还需要安装easy_install和pip这两个最常用工具。
整个安装过程，我总结过如下一个Shell脚本（以安装Python2.7.8为例，以root权限运行），供参考：https://github.com/smilejay/shell/blob/master/sh2014/install_py27_on_centos.sh
#!/bin/bash# a script to install python 2.7 on CentOS 6.x system.# CentOS 6.x has python 2.6 by default, while some software (e.g. django1.7)# need python 2.7.# install some necessary tools & libsecho "install some necessary tools & libs"yum groupinstall "Development tools"yum install openssl-devel zlib-devel ncurses-devel bzip2-devel readline-develyum install libtool-ltdl-devel sqlite-devel tk-devel tcl-develsleep 5# download and install pythonversion='2.7.8'python_url="https://www.python.org/ftp/python/$version/Python-${version}.tgz"# check current python versionecho "before installation, your python version is: $(python -V &2>1)"python -V 2>&1 | grep "$version"if [ $? -eq 0 ]; then echo "current version is the same as this installation." echo "Quit as no need to install." exit 0fiecho "download/build/install your python"cd /tmpwget $python_urltar -zxf Python-${version}.tgzcd Python-${version}./configuremake -j 4make installsleep 5echo "check your installed python"python -V 2>&1 | grep "$version"if [ $? -ne 0 ]; then echo "python -V is not your installed version" /usr/local/bin/python -V 2>&1 | grep "$version" if [ $? -ne 0 ]; then echo "installation failed. use '/usr/local/bin/python -V' to have a check" fi exit 1fisleep 5# install setuptoolsecho "install setuptools"wget https://bitbucket.org/pypa/setuptools/raw/bootstrap/ez_setup.pypython ez_setup.py# check easy_install versioneasy_install --versionsleep 5# install pip for the new pythonecho "install pip for the new python"easy_install pip# check pip versionpip -Vecho "Finished. Well done!"echo "If 'python -V' still shows the old version, you may need to re-login."echo "And/or set /usr/local/bin in the front of your PATH environment variable."echo "-------------------------"
一篇参考文档：
https://github.com/h2oai/h2o/wiki/Installing-python-2.7-on-centos-6.3.-Follow-this-sequence-exactly-for-centos-machine-only
Original article: CentOS 6.x升级Python到2.7
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