How to do variable substitution in json

Question

The below table insert command takes a json as an input. I am trying to do variable substitution but it didnt work. What is the right way to do it.

note: echo on numberoflines works.

aws dynamodb put-item     --table-name staging-metrics     --item '{ "count": {"S": $numberoflines} }'

tried alternatives like "$(numberoflines)" but that stores $(numberoflines) literally in table.

Answer 1

I'm not sure about this... but isn't --item "{ \"count\": {\"S\": $numberoflines} }"