Translates an AWS instance ID to the private DNS name

id2dns.sh

function id2dns() {
    if [ -z "$1" ]; then
        echo "Usage: id2ip instanceID [instanceID...]"
    else
        aws ec2 describe-instances --instance-ids $* --output text --query 'Reservations[].Instances[].PrivateDnsName'
    fi
}

Requires:

• the AWS CLI
• the jq command
• valid AWS credentials set in the shell

Update 2020-08-14: jq not needed any more, using the --output text and --query is just as fine, and doesn't need an additional software :-)