Force mongodb to output strict JSON

The MongoDB shell speaks Javascript, so the answer is simple: use JSON.stringify(). If your command is db.serverStatus(), then you can simply do this:

JSON.stringify(db.serverStatus())

This won't output the proper "strict mode" representation of each of the fields ({ "floatApprox": <number> } instead of { "$numberLong": "<number>" }), but if what you care about is getting standards-compliant JSON out, this'll do the trick.

I have not found a way to do this in the mongo shell, but as a workaround, mongoexport can run queries and its output uses strict mode and can be piped into other commands that expect JSON input (such as json_pp or jq). For example, suppose you have the following mongo shell command to run a query, and you want to create a pipeline using that data:

db.myItemsCollection.find({creationDate: {$gte: ISODate("2016-09-29")}}).pretty()

Convert that mongo shell command into this shell command, piping for the sake of example to `json_pp:

mongoexport --jsonArray -d myDbName -c myItemsCollection -q '{"creationDate": {"$gte": {"$date": "2016-09-29T00:00Z"}}}' | json_pp

You will need to convert the query into strict mode format, and pass the database name and collection name as arguments, as well as quote properly for your shell, as shown here.