Splitting extra columns in a text file into separate lines (keeping first column) - bash

Question

I'm going to try to describe my problem and my end goal as best as I can, here it goes:
I have a script that fetches AWS ELB information (elb name + ports that's associated with a specific certifican arn).
So, in the end I have a text file (I call it elb_ports) and it looks something like this:
ccds-lb 636
cf-router 443 4443
dev-cf-router 443 4443
eng-jenkins-monit 443
gitlab-lb 443
gitlab-mattermost-elb 443
jenkins-np-elb 443
saml 443
uaa 443
I have another script that comes after that which I want it to go through that elb_ports file and replace the certificates with a new one, but according to Amazon's documentation: It says in order to replace the certificates, I need two things from that elb_ports file. The load balancer name and the load balancer port.
So basically their command looks like this
aws elb set-load-balancer-listener-ssl-certificate \
--load-balancer-name my-load-balancer \
--load-balancer-port 443 \
--ssl-certificate-id arn:aws:iam::123456789012:server-certificate/my-new-certificate
I want to be able to loop through the file and execute the command above to each elb and port, but my problem is with the elbs that has multiple ports associated with the cert like: cf-router 443 4443 for example.
So my idea was to split that into two lines, so like this:
cf-router 443
cf-router 4443
But I'm not sure how to add cf-router (for example) to the ports that come after the first one (there could be more than two ports using the same cert).
I hope I was able to explain my problem and end goal clearly, if this isn't a good method, I'm open to suggestions also.
EDIT: Perhaps something like this is beneficial, but not sure how to tailor it to my needs.. Like put each line in an array and the space as a delimiter and then loop through each line putting arr(1) (load balancer name) and then the load balancer port, but not sure how to count and go through >arr(2) in bash.

Answer 1

To split out your extra columns into separate lines:
while read -r lb_name lb_ports_str; do ## split line into lb name and port list string
read -r -a lb_ports <<<"$lb_ports_str" ## split out port list string into an array
for port in "${lb_ports[#]}"; do ## iterate through that array
printf '%s %s\n' "$lb_name" "$port" ## handle each port separately
done
done <elb_ports ## reading lines from elb_ports
Of course, that printf could be any other line referring to $lb_name and $port -- meaning you could potentially run your code that's installing new certificates here.