python 升级后 yum 无法使用 File "/usr/bin/yum", line 30 except KeyboardInterrupt, e: `/usr/libexec/urlgrabber-ext-down`

原因为升级python后新建了软连接指向了新版本，除非同时升级yum不然无法使用。需要手动更改报错文件指向新版本后即可解决。

[root@localhost pdserving]# yum install -y tree
  File "/usr/bin/yum", line 30
    except KeyboardInterrupt, e:
                            ^

# 查看路径
[root@localhost pdserving]# whereis python
python: /usr/bin/python /usr/bin/python2.7 /usr/lib/python2.7 /usr/lib64/python2.7 /etc/python /usr/include/python2.7 /usr/local/python3.8 /usr/local/python3.7 /usr/share/man/man1/python.1.gz
[root@localhost pdserving]# /usr/bin/python -V
Python 3.7.4
[root@localhost pdserving]# /usr/bin/python2.7 -V
Python 2.7.5

修改：/usr/bin/yum

# 将 第一行的路径改正确就可以了。
[root@localhost pdserving]# vi /usr/bin/yum

#!/usr/bin/python2.7
import sys
try:
    import yum
except ImportError:
    print >> sys.stderr, """\

修改：/usr/libexec/urlgrabber-ext-down

[root@localhost pdserving]# yum -y install tree
已加载插件：fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirrors.ustc.edu.cn
 * extras: mirrors.ustc.edu.cn
 * updates: mirrors.ustc.edu.cn
  File "/usr/libexec/urlgrabber-ext-down", line 28
    except OSError, e:
                  ^
SyntaxError: invalid syntax
  File "/usr/libexec/urlgrabber-ext-down", line 28
    except OSError, e:
                  ^
SyntaxError: invalid syntax

[root@localhost pdserving]# vi /usr/libexec/urlgrabber-ext-down 

#! /usr/bin/python2.7
#  A very simple external downloader
#  Copyright 2011-2012 Zdenek Pavlas