Tracing the origin of noTimeout cursors
I ended up using this command:

mongo --quiet --eval "var c=new Mongo();var o=[];db.adminCommand('listDatabases').databases.forEach(function(d){o=o.concat(c.getDB(d.name).currentOp(true).inprog.filter(function(d){return d.op=='query';}).map(function(d){return d.query;}));});o" &gt; cursor.json


The expanded form of the actual js in there is

var conn = new Mongo();
var cursorInfo = [];
db.adminCommand('listDatabases').databases.forEach(function(d) {
    var database = conn.getDB(d.name)
    cursorInfo = cursorInfo.concat(database.currentOp(true).inprog.filter(function(d) {
                return d.op == 'query';
            }).map(function(d) {
                return d.query;
            }));
});
cursorInfo


The command will get the information from db.currentOp(true).inprog about current querying cursors for every db and save it into the file cursor.json.