Automated DNS Lookup Shell Script

Create a linux shell script to automate multiple dns a record lookups. for d in $url; do dig $dnsserver +short A $d; done (or something similar, whatever works) The script will have a section to add DNS servers for the lookups. Another section to add all the domains that will be checked. The script will then output at the end of a file with a section for each relevant domain. # DOMAIN NAME1 A records from all the lookups minus any duplicates ... ... ... # DOMAIN NAME2 etc.. A records from all the lookups minus any duplicates ... ... ... Each DNS A record above will be input into a string. Another usage needed is to run in a folder with some files and have an update option which will build a new list of A records for each domain then check all files in a folder specified and update each domain name entry with updated A records with an option to remove or keep entries which do not show in a new lookup. There will be other entires already added into the file but the script will only modify recognized domain entries under the #comment tags until the next comment tag. There will be other unrelated comments in the file so maybe some marker is needed for relevant sections to the script. Also I don't want it adding to files that don't have any recognized domain entries this will be a separate option to append. It takes a bit to explain but I think it is quite simple and should not take long to finish. Thanks!