在CentOS 6.x上，默認自帶的Python是2.6.x版本，這個版本的Python有點老了，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務器就是使用CentOS6.x，所以也就有了升級Python到2.7的需求。

升級Python之前，需要先安裝一些工具和軟件庫，否則后面安裝Python或pip時可能出錯。
Python2.7通過源碼安裝，python可行執行程序默認是安裝在/usr/local/bin/，一般來在$PATH中，/usr/local/bin是優先使用的（如果不是，需要自己設置一下PATH環境變量）。
在安裝完python后，還需要安裝easy_install和pip這兩個最常用工具。

整個安裝過程，我總結過如下一個Shell腳本（以安裝Python2.7.8為例，以root權限運行），供參考：

https://github.com/smilejay/shell/blob/master/sh2014/install_py27_on_centos.sh

代碼如下:
#!/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 & libs
echo "install some necessary tools & libs"
yum groupinstall "Development tools"
yum install openssl-devel zlib-devel ncurses-devel bzip2-devel readline-devel
yum install libtool-ltdl-devel sqlite-devel tk-devel tcl-devel
sleep 5
 
# download and install python
version='2.7.8'
python_url="https://www.python.org/ftp/python/$version/Python-${version}.tgz"
 
# check current python version
echo "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 0
fi
 
echo "download/build/install your python"
cd /tmp
wget $python_url
tar -zxf Python-${version}.tgz
cd Python-${version}
./configure
make -j 4
make install
sleep 5
 
echo "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 1
fi
sleep 5
 
# install setuptools
echo "install setuptools"
wget https://bitbucket.org/pypa/setuptools/raw/bootstrap/ez_setup.py
python ez_setup.py
# check easy_install version
easy_install --version
sleep 5
 
# install pip for the new python
echo "install pip for the new python"