第一步：查看Centos版本及python版本
Centos版本
[root@qsh ~]# cat /etc/centos-release
CentOS Linux release 7.6.1810 (Core)python版本
[root@qsh ~]# python -V
Python 2.7.5
[root@qsh usr]# ll -l /usr/bin/python*
lrwxrwxrwx 1 root root 7 3月 29 22:44 /usr/bin/python -> python2
lrwxrwxrwx 1 root root 9 3月 29 22:44 /usr/bin/python2 -> python2.7
-rwxr-xr-x 1 root root 7136 11月 6 00:29 /usr/bin/python2.7第二步：从官网下载python对应版本的包并解压
[root@qsh packages]# wget https://www.python.org/ftp/python/2.7.15/Python-2.7.15.tgz
[root@qsh packages]# tar zxvf Python-2.7.15.tgz第三步：配置、编译、安装
安装gcc(在编译时会依赖)
yum install gcc* openssl openssl-devel ncurses-devel.x86_64 bzip2-devel sqlite-devel python-devel zlib配置、编译、安装
cd Python-2.7.15
./configure --prefix=/usr/local # [配置]指定可执行文件、库文件、配置文件、资源文件的安装路径。若没有权限加sudo
make # 编译
make altinstall # 不要使用make install，否则会覆盖系统自带python第四步：安装后环境检查
python安装后的版本
[root@qsh ~]# python -V # 发现版本还是原版本Python 2.7.5安装前后的python对比
[root@qsh ~]# ll -l /usr/bin/python* # 系统自带的
lrwxrwxrwx 1 root root 7 2019/03/03 14:24:13 /usr/bin/python -> python2
lrwxrwxrwx 1 root root 9 2019/03/03 14:24:13 /usr/bin/python2 -> python2.7
-rwxr-xr-x 1 root root 7216 2018/10/31 07:46:45 /usr/bin/python2.7
-rwxr-xr-x 1 root root 1835 2018/10/31 07:46:26 /usr/bin/python2.7-config
lrwxrwxrwx 1 root root 16 2019/03/26 17:13:24 /usr/bin/python2-config -> python2.7-config
lrwxrwxrwx 1 root root 14 2019/03/26 17:13:24 /usr/bin/python-config -> python2-config
[root@qsh ~]# ll -l /usr/local/bin/python* # 手工安装的
-rwxr-xr-x 1 root root 8296384 2019/03/26 17:16:56 /usr/local/bin/python2.7
-rwxr-xr-x 1 root root 1687 2019/03/26 17:17:05 /usr/local/bin/python2.7-config备份旧版本，连接新版本
[root@qsh ~]# mv /usr/bin/python /usr/bin/python2.7.5
[root@qsh ~]# ll -l /usr/bin/python*
lrwxrwxrwx 1 root root 9 2019/03/03 14:24:13 /usr/bin/python2 -> python2.7
-rwxr-xr-x 1 root root 7216 2018/10/31 07:46:45 /usr/bin/python2.7
lrwxrwxrwx 1 root root 7 2019/03/03 14:24:13 /usr/bin/python2.7.5 -> python2 # 改为2.7.5
-rwxr-xr-x 1 root root 1835 2018/10/31 07:46:26 /usr/bin/python2.7-config
lrwxrwxrwx 1 root root 16 2019/03/26 17:13:24 /usr/bin/python2-config -> python2.7-config
lrwxrwxrwx 1 root root 14 2019/03/26 17:13:24 /usr/bin/python-config -> python2-config
[root@qsh ~]# ln -s /usr/local/bin/python2.7 /usr/bin/python # 增加连接
[root@qsh ~]# ll -l /usr/bin/python*
lrwxrwxrwx 1 root root 24 2019/03/26 17:20:18 /usr/bin/python -> /usr/local/bin/python2.7 # 新增的，并指向新安装的python
lrwxrwxrwx 1 root root 9 2019/03/03 14:24:13 /usr/bin/python2 -> python2.7
-rwxr-xr-x 1 root root 7216 2018/10/31 07:46:45 /usr/bin/python2.7
lrwxrwxrwx 1 root root 7 2019/03/03 14:24:13 /usr/bin/python2.7.5 -> python2
-rwxr-xr-x 1 root root 1835 2018/10/31 07:46:26 /usr/bin/python2.7-config
lrwxrwxrwx 1 root root 16 2019/03/26 17:13:24 /usr/bin/python2-config -> python2.7-config
lrwxrwxrwx 1 root root 14 2019/03/26 17:13:24 /usr/bin/python-config -> python2-config再次检查python版本
[root@qsh ~]# python -V
Python 2.7.15若想访问老版本python(如2.7.5版本)
[root@qsh ~]# python2.7.5 -V
Python 2.7.5第五步：yum的设置(系统预装的yum引用的老版本python)
[root@qsh ~]# yum -y install epel-release
There was a problem importing one of the Python modules
required to run yum. The error leading to this problem was:
No module named yum #这时候报错了
Please install a package which provides this module, or
verify that the module is installed correctly.
It's possible that the above module doesn't match the
current version of Python, which is:
2.7.13 (default, Apr 2 2017, 04:48:29)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-11)]
If you cannot solve this problem yourself, please go to
the yum faq at:
http://yum.baseurl.org/wiki/Faq
#解决方法
[root@qsh ~]# vi /usr/bin/yum
首行的#!/usr/bin/python 改为 #!/usr/bin/python2.7
改完之后继续安装，又报错...
ImportError: No module named urlgrabber.grabber
[root@qsh ~]# vi /usr/libexec/urlgrabber-ext-down
首行的#!/usr/bin/python 改为 #!/usr/bin/python2.7第六步：升级 python 后，安装 pip 工具
1. 下载安装
wget https://bootstrap.pypa.io/get-pip.py
python get-pip.py2. 设置软连接
ln -s /usr/local/python27/bin/pip2.7 /usr/bin/pip
#安装 ipython
pip install ipython==1.2.1
ln -s /usr/local/python27/bin/ipython /usr/bin/ipython
