TIL: jq can walk arbitrarily nested JSON with `..`

Recursive descent in jq (`..`) finds a key no matter how deep it is buried — perfect for spelunking a cloud API response you did not write.

I spent too long writing explicit paths to pull one field out of a deeply nested AWS describe-* response. jq already had the answer.

The .. operator does a recursive descent over the whole document. Combine it with select to grab every occurrence of a key regardless of nesting depth:

1# every value under any "arn" key, at any depth2aws ec2 describe-instances | jq '.. | .arn? // empty'

It composes with select for conditional matches too — say you only want ARNs belonging to a specific service, buried at any depth:

1aws ec2 describe-instances | jq '.. | .arn? // empty | select(contains("ec2"))'

Two minutes saved becomes twenty when you stop hand-writing paths into responses you did not design.