1、

[root@centos7pc1 ~]# gcc --version
bash: gcc: command not found...

2、

[root@centos7pc1 ~]# yum install gcc gcc-c++ kernel-devel -y
Loaded plugins: fastestmirror, langpacks
Existing lock /var/run/yum.pid: another copy is running as pid 3032.
Another app is currently holding the yum lock; waiting for
 
 it to exit...
  The other application is: PackageKit
    Memory : 151 M RSS (1.0 GB VSZ)
…………
…………
  Verifying  : kernel-devel-3.10.0-1160.11.1.el7.x86_64                                                                          4/5
  Verifying  : cpp-4.8.5-44.el7.x86_64                                                                                           5
 
/5

Installed:
  gcc.x86_64 0:4.8.5-44.el7            gcc-c++.x86_64 0:4.8.5-44.el7            kernel-devel.x86_64 0:3.10.0-1160.11.1.el7

Dependency Installed:
  cpp.x86_64 0:4.8.5-44.el7                                   libstdc++-devel.x86_64 0:4.8.5-44.el7

Complete!

3、

[root@centos7pc1 ~]# gcc --version
gcc (GCC) 
 
4.8.5 20150623 (Red Hat 4.8.5-44)
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.