CentOS 6.x系统升级Python到2.7版本的Shell脚本分享

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：

#!/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"
easy_install pip
# check pip version
pip -v
 
echo "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 "-------------------------"