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：

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 & 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 "-------------------------"