How to describe instances from all regions using AWS CLI

for region in `aws ec2 describe-regions --output text | cut -f3`
do
     echo -e "\nListing Instances in region:'$region'..."
     aws ec2 describe-instances --region $region
done

As of Today (30-01-2017), You will get list of instances from below 14 regions are available in AWS

ap-south-1

eu-west-2

eu-west-1

ap-northeast-2

ap-northeast-1

sa-east-1

ca-central-1

ap-southeast-1

ap-southeast-2

eu-central-1

us-east-1

us-east-2

us-west-1

us-west-2