Q:

Parsing json with awk/sed in bash to get key value pair

I have read many existing questions at SO but none of them answers what I am looking for. I know it is difficult to parse json in bash using sed/awk but I only need a few key-value pairs per record out of a whole list of key-value pairs per record. I want to do this because it will be faster as the main JSON is pretty big with millions of records. 
The JSON format is like following:
{
    "documents":
    [
        {
            "title":"a",   //needed
            "description":"b",  //needed
            "id":"c",  //needed
            ....(some more:not useful)....
            "conversation":
            [
                {
                    "message":"",
                    "id":"d",   //not needed
                    .....(some more)....
                    "createDate":"e",   //not needed
                },
                ...(some more messages)....
            ],
            "createDate":"f",  //needed
            ....(many more labels).....
        }
    ],
    ....(some more global attributes)....
}

Now for this I require attributes which are marked as needed but their common key make it a problem to get by simple sed/awk. Could anyone suggest if we can do it with sed/awk. if possible any help to achieve the same would be appreciated.
P.S.: I know about jsawk but I do not want to introduce any dependency, so if possible please suggest usage of sed/awk.
EDIT: Multiple extries of the format given below(as in document we have a list)
"title":"a",
"description":"b"
"id":"c"
"createDate":"f"

EDIT: The JSON is without any spaces. It has been formated for readability.

A:

I would advise that you use 'jq', or a real JSON parser. You can't "parse" JSON with arbitrary regular expressions. You could hack something with awk, but that will break easily if your input has a form you didn't anticipate.
So, the answer is, introduce a cheap dependency (jq, or similar tool), and script around that.  Unless you're running this script in a router or an embedded computer, chances are you can easily install jq.

