SHELL

install nginx amazon linux 2

$ sudo amazon-linux-extras list | grep nginx
 38  nginx1=latest            disabled      [ =stable ]

$ sudo amazon-linux-extras enable nginx1
 38  nginx1=latest            enabled      [ =stable ]
        
Now you can install:
$ sudo yum clean metadata
$ sudo yum -y install nginx
    
$ nginx -v
nginx version: nginx/1.16.1

install nginx in amazon linux 2

$ sudo amazon-linux-extras list | grep nginx
 38  nginx1=latest            disabled      [ =stable ]

$ sudo amazon-linux-extras enable nginx1
 38  nginx1=latest            enabled      [ =stable ]
        
Now you can install:
$ sudo yum clean metadata
$ sudo yum -y install nginx
    
$ nginx -v
nginx version: nginx/1.16.1