AWS CLI returns an empty array on filter. I want to be able to count the number of elements in that array:
{ "Reservations": [] }
vs
{ "Reservations": [ { "OwnerId": "124531353552" ...... } ] }
So if there are no results I should get back 0 (the first example).
tl;dr:
On mac, install jq first via brew.
brew install jq. Run your query as you did before by adding the pipe jq command.
Eg:
aws batch list-jobs --job-queue MY-QUEUE-NAME --job-status RUNNABLE | jq '.jobSummaryList | length'
Explanation
aws batch list-jobs --job-queue MY-QUEUE-NAME --job-status RUNNABLE when running this command the response is in the format of
{"jobSummaryList": []}
So adding the | jq '.jobSummaryList | length' gives me the count of object inside that list. And for you it will be 'Reservations'