Python版本升级
CentOS 6.3自带的Python版本为2.6，首先需要升级到2.7版本。由于旧版本的Python已被深度依赖，所以不能卸载原有的Python，只能全新安装。
1.下载Python-2.7.4.tgz
wget http://python.org/ftp/python/2.7.4/Python-2.7.4.tgz
2. 解压安装，命令如下:
1 tar -xvf Python-2.7.4.tgz
2 cd Python-2.7.4
3 ./configure --prefix=/usr/local/python2.7
4 make
5 make install
3. 创建链接来使系统默认python变为python2.7
mv /usr/bin/python /usr/bin/python.old
ln-s /usr/local/python2.7/bin/python2.7 /usr/bin/python
4. 查看Python版本
python –V
5. 修改yum配置（否则yum无法正常运行）
vim /usr/bin/yum
将第一行的#!/usr/bin/python修改为系统原有的python版本地址#!/usr/bin/python2.6
至此CentOS6.3系统Python已成功升级至2.7.4版本
安装pip
Pip是一个安装和管理python包的工具。
安装方法如下：
1. 下载pip，地址 https://bootstrap.pypa.io/get-pip.py
2. 执行安装命令
yum install setuptool zlib* -y
pythonget-pip.py
3. 创建连接（否则会报错提示“命令不存在”）
ln -s /usr/local/python2.7/bin/pip /usr/bin/pip
测试:
[[email protected] ~]# pip install redis
Collecting redis/usr/local/python2.7/lib/python2.7/site-packages/pip/_vendor/requests/packages/urllib3/util/ssl_.py:90: InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately and may cause certain SSL connections to fail. For more information, see https://urllib3.readthedocs.org/en/latest/security.html#insecureplatformwarning.
InsecurePlatformWarning
Downloading redis-2.10.5-py2.py3-none-any.whl (60kB)100% |################################| 61kB 759kB/s
Installing collected packages: redis
Successfully installed redis-2.10.5
至此pip安装完成!
如果安装pip时报如下错误：ImportError: cannot import name HTTPSHandle
执行 yum install sqlite-devel
如果报下面错误
说明pip命令不可用，有可能是链接没有做
[[email protected] ~]# ll /usr/bin/pip-rwxr-xr-x 1 root root 281 Jul 1 2015 /usr/bin/pip
[[email protected]~]# ln -s /usr/local/python2.7/bin/pip /usr/bin/pip
ln: creating symbolic link `/usr/bin/pip': File exists
[[email protected] ~]#
[[email protected]~]# \ln -s /usr/local/python2.7/bin/pip /usr/bin/pip
ln: creating symbolic link `/usr/bin/pip': File exists
[[email protected] ~]# mv /usr/bin/pip /tmp/##如果提示文件存在，移走原有的文件，重新做软连接
[[email protected]~]# ln -s /usr/local/python2.7/bin/pip /usr/bin/pip
[[email protected]~]# ll /usr/bin/pip
lrwxrwxrwx1 root root 28 Dec 26 17:28 /usr/bin/pip -> /usr/local/python2.7/bin/pip
