Using jq to modify files

Insert/Append

echo '{"hello": "world"}' | jq --arg foo bar '. + {foo: $foo}'
OR
echo '{"hello": "world"}' | jq '. + {foo: "bar"}'

{
  "hello": "world",
  "foo": "bar"
}

And “directly” in a file:

jq '.path += { "claims": "bar" } ' file.json > file1.json && mv file1.json file.json

jq can not edit in place.

Replace

echo '{"hello": "world"}' | jq '. + {hello: "bar"}'

Delete

echo '{"hello": "world", "foo": "bar"}' | jq '. | del(.foo)'