mongos> shellHelper
function (command, rest, shouldPrint) {
    command = command.trim();
    var args = rest.trim().replace(/\s*;$/, "").split("\s+");
    if (!shellHelper[command])
        throw Error("no command [" + command + "]");
    var res = shellHelper[command].apply(null, args);
    if (shouldPrint) {
        shellPrintHelper(res);
    }
    return res;
}                                                                                                                                                                                                     

mongos> "a b".split("\s+")                                                                                                                                                                              [ "a b" ]      // not split by space                                                                                                                                                                                         

mongos> "a\s+b".split("\s+")                                                                                                                                                                            [ "a", "b" ]  // split by the "\s+" string                                                                                                                                                                                           
  
mongos> "a b".split(/\s+/)                                                                                                                                                                              [ "a", "b" ]  // split by space           
mongos> "a     b".split(/\s+/)                                                                                                                                                                          [ "a", "b" ]  // split by multiple spaces