I had 70 different domain names that I need to add in a ssl cnf file for creating a certificate request.
The 70 different domain names was in a text file, one per line:
In order to create the alternative names list, I used this bash oneliner:
teller=1; for i in `cat /tmp/disse2`; do echo "DNS.$teller = $i"; teller=$((teller+1)); done
which then would give me:
DNS.1 = domainname1.something.com
DNS.2 = domainname2.somehing.com
DNS.70 = and-so-forth-until 70
This could be useful, if you have for instance hundreds or thousands of lines where you have to add a incremental value per line.