EC2 Snapshots whose AMI has been deleted

missing-amis.sh

echo "AMI's from snapshots which no longer exist"; 
echo "----------------------------------"; 

for i in `aws describe-snapshots | grep -o "ami-\([0-9]\|[a-z]\)\+" | sort -u`; do 
    if [[ -n `aws dim $i | grep requestId` ]]; then 
        echo "$i"; else echo ""; 
    fi; 
done;