jq works on set of filters. Each filtering step produce a result which can be den further filtered

json='{"person": {"name": "Ivo", "phone": "123"}}'
echo $json | jq .person.name

is the same as

echo $json | jq ".person | .name"

because the first | will produce {name: ‘Ivo’} which will be then filtered.

Extract multiple fields

This is done by enumerating the fields with ,

Just do

echo $json | jq ".person | (.name,.phone)"

But if you want to concatente them add echo $json | jq “.person | {name_with_phone:(.name + “-” + .phone)}” { “name_with_phone”: “Ivo-123” }

..and finally extract only the name_with_phone

echo $json | jq ".person | {name_with_phone:(.name + \"-\" + .phone)} | .name_with_phone" 

..and to get only the value add -r echo $json | jq -r “.person | {name_with_phone:(.name + “-” + .phone)} | .name_with_phone” Ivo-123

Here is an example where I grab all the location ids from all parents

cat * | jq '.deviceLocationUpdate.location | .locationId,.parent.locationId,.parent.parent.locationId,.parent.parent.parent.locationId,.parent.parent.parent.parent.locationId' | sort | uniq