yum安装nginx时报错：No package nginx available. Error: Nothing to do

[root@localhost ~]# yum install nginx -y
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile

• base: mirrors.cqu.edu.cn
• extras: mirrors.njupt.edu.cn
• updates: mirrors.njupt.edu.cn
  No package nginx available.
  Error: Nothing to do

vim /etc/yum.repos.d/nginx.repo

在文件中写入以下内容：

[nginx]
name=nginx repo
baseurl=http://nginx.org/packages/centos/basearch/
gpgcheck=0
enabled=1

然后执行yum install nginx -y
[root@localhost ~]# yum install nginx -y
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile

• base: mirrors.cqu.edu.cn
• extras: mirrors.njupt.edu.cn
• updates: mirrors.njupt.edu.cn
  nginx | 2.9 kB 00:00:00
  nginx/7/x86_64/primary_db | 55 kB 00:00:01
  Resolving Dependencies
  --> Running transaction check
  ---> Package nginx.x86_64 1:1.18.0-1.el7.ngx will be installed
  --> Finished Dependency Resolution

Dependencies Resolved