cat region_loop.sh 
#!/bin/bash
REGIONS=('us-east-1' 'us-east-2' 'us-west-1' 'us-west-2' 'eu-west-1' 'eu-west-2')
for REGION in "${REGIONS[@]}"; do
  echo "${REGION}"
done
$ ./region_loop.sh us-east-1 us-east-2 us-west-1 us-west-2 eu-west-1 eu-west-2