This little script helps you SSH to your EC2 instance via an instance-id. You will still need to have your pem files in the .ssh folder.

ec2ssh.sh

ec2ssh() 
{
	if [[ ! -z "$1" ]]; then 
		# echo "cfn"
		INSTANCE_ID_INPUT=$1
	else 
		echo -n "Enter Instance ID: "
		read INSTANCE_ID_INPUT
	fi
  
	# Grab Public IP of Instance
	PUBLIC_IP="$(aws ec2 describe-instances --instance-id "$INSTANCE_ID_INPUT" | grep PublicIpAddress | awk -F\" '{print $4}')"
	
	if [[ ! -z "$PUBLIC_IP" ]]; then
		# If $PUBLIC_IP is not empty
		echo -e "PublicIPAddress:\t"$PUBLIC_IP
		KEY_NAME="$(aws ec2 describe-instances --instance-id "$INSTANCE_ID_INPUT" | grep KeyName | awk -F\" '{print $4}')"
		echo -e "Using SSH Key:\t\t"$KEY_NAME
		echo -e "Attempting to connect to "$INSTANCE_ID_INPUT" at "$PUBLIC_IP".\n"
		ssh -i ~/.ssh/$KEY_NAME.pem ec2-user@$PUBLIC_IP
		
	else 
		echo "This instance "$INSTANCE_ID_INPUT" does not have a Public IP."
	fi

	
}