How can I pass a variable from a php script to a terminal command?

Question

I have a terminal command that I've been running manually while I get my site up and running. It looks like this...

for ((i=1000; i<=2000; i++)); do  
curl -s --data '{"jsonrpc":"2.0", "method":"api.get_thing", "params":['$i'], "id":1}' https://api.site.com > /save_to_this_path/$i.txt; done

It works fine because I'm currently getting caught up to number 2000.

But once I get to 2000, I want to run a cron job every few minutes to get any new data.

I have a php script, /var/script.php

That script pulls this data from my database:

$myHighestRecord = 2000;
$apiHighestRecord = 2500;

In this example, the API is 500 records ahead of me, and I need to process those records. So I want my cron job to do something like...

curl /var/script.php

for ((i= $myHighestRecord; i<= $apiHighestRecord; i++)); do  
curl -s --data '{"jsonrpc":"2.0", "method":"api.get_thing", "params":['$i'], "id":1}' https://api.site.com > /save_to_this_path/$i.txt; done

I'm pretty sure this is possible but can't seem to figure out exactly how to do it. Any recommendations? Thanks.