维护更新CentOS 8 Linux系统运行命令报错如下：
[root@iZwz92jeancylpcm6qlws1Z yum.repos.d]# yum upgrade
Repository extras is listed more than once in the configuration
Repository epel is listed more than once in the configuration
Last metadata expiration check: 0:00:14 ago on Thu 28 Oct 2021 02:02:47 PM CST.
Error:
Problem: cannot install both libpcap-14:1.9.1-5.el8.x86_64 and libpcap-14:1.9.1-4.el8.x86_64
- package libpcap-devel-14:1.9.1-4.el8.x86_64 requires libpcap = 14:1.9.1-4.el8, but none of the providers can be installed
- cannot install the best update candidate for package libpcap-14:1.9.1-4.el8.x86_64
- problem with installed package libpcap-devel-14:1.9.1-4.el8.x86_64
(try to add '--allowerasing' to command line to replace conflicting packages or '--skip-broken' to skip uninstallable packages or '--nobest' to use not only best candidate packages)
出现上述–skip-broken的原因并不在于缓存问题，而是libpcap软件包没有卸载完导致，我们可以通过查询相关的rpm包删除干净，再进行系统的更新。
[root@iZwz92jeancylpcm6qlws1Z yum.repos.d]# rpm -qa | grep libpcap |xargs rpm -e --nodeps现在可以使用yum upgrade命令更新系统啦
