yum/rpm error: Failed to initialize NSS library centos7

今天在一台测试机上使用yum命令安装包时，出现error: Failed to initialize NSS library错误，rpm命令也同样如此，但是系统还可以正常使用。

完整报错内容如下：

error: Failed to initialize NSS library
There was a problem importing one of the Python modules
required to run yum. The error leading to this problem was:

   cannot import name ts

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:
2.7.5 (default, Aug  4 2022, 00:39:18)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-16)]

If you cannot solve this problem yourself, please go to
the yum faq at:
  http://yum.baseurl.org/wiki/Faq

error: Failed to initialize NSS library

There was a problem importing one of the Python modules

required to run yum. The error leading to this problem was:

cannot import name ts

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:

2.7.5 (default, Aug 4 2022, 00:39:18)

[GCC 4.8.5 20150623 (Red Hat 4.8.5-16)]

If you cannot solve this problem yourself, please go to

the yum faq at:

http://yum.baseurl.org/wiki/Faq

发生这种情况的原因可能是仅升级了个别的nss-softokn-freebl包组，没有同时升级nss或nspr等，也有可能是rpm指定卸载了某个包组导致异常。

网上的方法无非是rpm2cpio提取库，但是如果你不知道是由于什么操作导致的，解决起来也会比较麻烦，所以rpm2cpio要提取多个软件包组，并不能指定一个。

包组可通过https://centos.pkgs.org/查找并下载到本地，进行提取

rpm2cpio nss-util-3.44.0-4.el7_7.x86_64.rpm | cpio -idmv
yes | cp -R ./usr/lib64/* /usr/lib64/

1 2	rpm2cpio nss-util-3.44.0-4.el7_7.x86_64.rpm \| cpio -idmv yes \| cp -R ./usr/lib64/* /usr/lib64/

此时再次执行rpm/yum命令，如果依旧报错，则继续提取相关库

rpm2cpio nss-softokn-freebl-3.44.0-8.el7_7.x86_64.rpm | cpio -idmv
yes | cp -R ./usr/lib64/* /usr/lib64/
rpm2cpio nspr-4.21.0-1.el7.x86_64.rpm | cpio -idmv
yes | cp -R ./usr/lib64/* /usr/lib64/