yum install gcc
结果报错：
[root@localhost ~]# yum install gcc
Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile
* epel: ftp.iij.ad.jp
Resolving Dependencies
--> Running transaction check
---> Package gcc.x86_64 0:4.8.5-36.el7_6.2 will be installed
--> Processing Dependency: libgomp = 4.8.5-36.el7_6.2 for package: gcc-4.8.5-36.el7_6.2.x86_64
--> Processing Dependency: cpp = 4.8.5-36.el7_6.2 for package: gcc-4.8.5-36.el7_6.2.x86_64
--> Processing Dependency: glibc-devel >= 2.2.90-12 for package: gcc-4.8.5-36.el7_6.2.x86_64
--> Running transaction check
---> Package cpp.x86_64 0:4.8.5-36.el7_6.2 will be installed
---> Package glibc-devel.x86_64 0:2.17-260.el7_6.6 will be installed
--> Processing Dependency: glibc-headers = 2.17-260.el7_6.6 for package: glibc-devel-2.17-260.el7_6.6.x86_64
--> Processing Dependency: glibc = 2.17-260.el7_6.6 for package: glibc-devel-2.17-260.el7_6.6.x86_64
--> Processing Dependency: glibc-headers for package: glibc-devel-2.17-260.el7_6.6.x86_64
---> Package libgomp.i686 0:4.8.5-36.el7_6.2 will be installed
--> Running transaction check
---> Package glibc.i686 0:2.17-260.el7_6.6 will be installed
--> Processing Dependency: glibc-common = 2.17-260.el7_6.6 for package: glibc-2.17-260.el7_6.6.i686
--> Processing Dependency: libfreebl3.so(NSSRAWHASH_3.12.3) for package: glibc-2.17-260.el7_6.6.i686
--> Processing Dependency: libfreebl3.so for package: glibc-2.17-260.el7_6.6.i686
---> Package glibc-headers.x86_64 0:2.17-260.el7_6.6 will be installed
--> Processing Dependency: kernel-headers >= 2.2.1 for package: glibc-headers-2.17-260.el7_6.6.x86_64
--> Processing Dependency: kernel-headers for package: glibc-headers-2.17-260.el7_6.6.x86_64
--> Running transaction check
---> Package glibc.i686 0:2.17-260.el7_6.6 will be installed
--> Processing Dependency: glibc-common = 2.17-260.el7_6.6 for package: glibc-2.17-260.el7_6.6.i686
---> Package kernel-headers.x86_64 0:3.10.0-957.27.2.el7 will be installed
---> Package nss-softokn-freebl.i686 0:3.36.0-5.el7_5 will be installed
--> Finished Dependency Resolution
Error: Package: glibc-2.17-260.el7_6.6.i686 (updates)
Requires: glibc-common = 2.17-260.el7_6.6
Installed: glibc-common-2.17-307.el7.1.x86_64 (@anaconda)
glibc-common = 2.17-307.el7.1
Available: glibc-common-2.17-260.el7.x86_64 (base)
glibc-common = 2.17-260.el7
Available: glibc-common-2.17-260.el7_6.3.x86_64 (updates)
glibc-common = 2.17-260.el7_6.3
Available: glibc-common-2.17-260.el7_6.4.x86_64 (updates)
glibc-common = 2.17-260.el7_6.4
Available: glibc-common-2.17-260.el7_6.5.x86_64 (updates)
glibc-common = 2.17-260.el7_6.5
Available: glibc-common-2.17-260.el7_6.6.x86_64 (updates)
glibc-common = 2.17-260.el7_6.6
You could try using --skip-broken to work around the problem
You could try running: rpm -Va --nofiles --nodigest
解决方案：
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
sed -i 's/$releasever/7/g' /etc/yum.repos.d/CentOS-Base.repo
yum repolist
重新安装，即可成功：
yum install gcc