CentOS7 升级python同时解决yum损坏问题

CentOS7中的python版本为python2.7.5，升级到最新版的python时需要注意两个问题

• 新版的python安装好后要修改python的系统默认指向问题
• 升级到最新版python后yum报错的问题

下面对新版的安装步骤进行说明。

　一、下载并安装最新版python

　　1.下载并解压

# wget https://www.python.org/ftp/python/3.5.2/Python-3.5.2.tgz
# tar -zxf Python-3.5.2.tgz

　　2.安装Python

# cd Python-3.5.2/# ./configure # make# make install

查看是否安装成功

# /usr/local/bin/python3.5Python 3.5.2 (default, Jul 24 2016, 14:46:50) [GCC 4.8.5 20150623 (Red Hat 4.8.5-4)] on linuxType "help", "copyright", "credits" or "license" for more information.>>> 

　　3.修改python的系统默认指向，修改软链接

　　正常情况下，新版本的python安装后系统等其他应用指向的python环境依然是老版本的python，

　　如果删除老版本后再装新版本会面临很多难以定位的麻烦，所以通常的做法是：

　　老版本依然保留，新版本并行存在。操作方法如下

（1）修改系统默认的python修改为2.7.5版本

# mv /usr/bin/python /usr/bin/python2.7.5

（2）创建软连接使python指向新版本

# ln -s /usr/local/bin/python3.5 /usr/bin/python

（3）检测是否更新成功

[[email protected] ~]# python
Python 3.5.2 (default, Jul 24 2016, 14:46:50)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-4)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> 

　二、yum报错问题解决

　　1.终端下输入yum后报错信息如下

[[email protected] ~]# yum
  File "/usr/bin/yum", line 30
    except KeyboardInterrupt, e:
                            ^
SyntaxError: invalid syntax

　　2.vim /usr/bin/yum

　　 修改python头部python为python2.7.5

#!/usr/bin/python2.7.5
import sys
try:
    import yum
except ImportError:
    print >> sys.stderr, """\
There was a problem importing one of the Python modules
required to run yum. The error leading to this problem was:

　　3.再次查看yum是否可用

[[email protected] ~]# yum
Loaded plugins: fastestmirror, langpacks
You need to give some command
Usage: yum [options] COMMAND

List of Commands:

check          Check for problems in the rpmdb
check-update   Check for available package updates
clean          Remove cached data
deplist        List a package‘s dependencies

... ...