升级Python导致yum报错

一天，需要在Linux服务器上面安装一个rpm包，结果运行yum命令的时候无论如何都会报错，如下：

[root@test bin]# yum
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
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:
2.7.10 (default, Sep  7 2015, 10:39:35)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-3)]
If you cannot solve this problem yourself, please go to
the yum faq at:
  http://yum.baseurl.org/wiki/Faq

报错信息中提到：

It's possible that the above module doesn't match the
current version of Python, which is:
2.7.10 (default, Sep  7 2015, 10:39:35)

所以怀疑和刚刚升级的Python有关系，但是也不能为了yum将刚刚升级的Python协助了啊，

我们进一步查看：

[root@test bin]# strace yum
execve("/usr/bin/yum", ["yum"], [/* 30 vars */]) = 0
brk(0)                                  = 0x1849000
........
stat("/usr/bin", {st_mode=S_IFDIR|0555, st_size=40960, ...}) = 0
stat("/usr/bin/yum", {st_mode=S_IFREG|0755, st_size=801, ...}) = 0
open("/usr/bin/yum.so", O_RDONLY)      = -1 ENOENT (No such file or directory)
open("/usr/bin/yummodule.so", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/bin/yum.py", O_RDONLY)      = -1 ENOENT (No such file or directory)
open("/usr/bin/yum.pyc", O_RDONLY)      = -1 ENOENT (No such file or directory)
stat("/usr/local/lib/python2.7/yum", 0x7fff5cca59c0) = -1 ENOENT (No such file or directory)
open("/usr/local/lib/python2.7/yum.so", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/local/lib/python2.7/yummodule.so", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/local/lib/python2.7/yum.py", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/local/lib/python2.7/yum.pyc", O_RDONLY) = -1 ENOENT (No such file or directory)
stat("/usr/local/lib/python2.7/plat-linux2/yum", 0x7fff5cca59c0) = -1 ENOENT (No such file or directory)
.....
write(2, "There was a problem importing on"..., 527There was a problem importing one of the Python modules
required to run yum. The error leading to this problem was:
  No module named yum
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:
2.7.10 (default, Sep  7 2015, 10:39:35)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-3)]
If you cannot solve this problem yourself, please go to
the yum faq at:
  http://yum.baseurl.org/wiki/Faq
 
) = 527
write(2, "\n", 1
)                      = 1
rt_sigaction(SIGINT, {SIG_DFL, [], SA_RESTORER, 0x343800f500}, {0x4e4a30, [], SA_RESTORER, 0x343800f500}, 8) = 0
brk(0x1907000)                          = 0x1907000
exit_group(1)                          = ?
[root@test bin]#

我们通过strace命令，发现日志中的下半部分，都是Python导致的错误，

然后想起原来系统中的Python是 2.66版本的，后来我将其升级成了2.7.10了

会不会就是这个问题导致的呢？  然后我从其他的服务器（同版本）中下载下来一个2.66的Python，放到/usr/bin目录下，并且重命名为 python2.6

然后执行命令查找yum的位置，并且vi打开yum文件，将第一行的Python改为 python2.6

将其他yum开头的几个脚本也都做修改

[root@test bin]# which yum
/usr/bin/yum
[root@test bin]# vi yum
[root@test bin]# head -n 1 yum*
==> yum <==
#!/usr/bin/python2.6
==> yum-builddep <==
#!/usr/bin/python2.6 -tt
==> yum-config-manager <==
#!/usr/bin/python2.6 -tt
==> yum-debug-dump <==
#!/usr/bin/python2.6 -tt
==> yum-debug-restore <==
#!/usr/bin/python2.6 -tt
==> yumdownloader <==
#!/usr/bin/python2.6
==> yum-groups-manager <==
#!/usr/bin/python2.6 -tt

再次运行yum命令,问题解决!

更多YUM相关教程见以下内容：