Use the AWSCLI to parse the Public IP from a describe-instances call to connect via SSH.

amznssh.sh

#!/bin/bash

# Default user uses different names, depending on OS.
# Amazon Linux = "ec2-user"
# Ubuntu = "ubuntu"
remote_user="ec2-user"

pem="/home/.ssh/YOUR_PRIVATE_KEY"
port=22

# Get this using describe_instances, or via the AWS Console.
instance="i-YOUR_AWS_INSTANCE_ID"

ssh $(aws ec2 describe-instances --instance-id $instance --query Reservations[].Instances[].NetworkInterfaces[].Association[].PublicIp[] | cut -c 6- | rev | cut -c 2- | rev)  -l $remote_user -i $pem -p $port