It's been years since I wrote perl. Any kind soul care to comment some of this code? It looks like the logic starts at the bottom, but I must admit defeat in truly understanding how it works!
grep for items with a 'creditcard' field
map each item to a string with its 'name' and 'creditcard' fields
for each string (and "name,creditcard\n"), print it
into 20150425.csv
* <> reads from file(s) specified as command-line arguments (data.json in this case)
* Option -0777 tells Perl to slurp the whole file
* Option -MJSON loads the JSON module