yum/rpm error: Failed to initialize NSS library centos7-工具盒子

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

|-------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 | 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/

|---------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | 1 2 3 4 | 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/ |

确保库已经成功覆盖至/usr/lib64/

如果到此，问题还是依旧，我建议你执行strace rpm，查看调用了哪些/lib64/下的库，然后进行提取覆盖

如果当然系统没有strace命令，可以通过rpm2cpio提取的方法，将bin文件提取出来，扔到系统bin目录下
思路就是如此，可以参考以上思路进行排查。

如果在cp覆盖的时候提示cannot access /lib64/libsoftokn3.so: No data available内容，建议通过rsync重新拷贝/lib64目录至/lib64.bak，将异常的文件过滤掉，然后将/lib64.bak与/lib64名称互换。