My jq cheat sheet

jq is pure awesomeness. If every you want to “grep” through JSON data on the command line, this is the tool for you. Unfortunately, I don’t use it everyday, so when I do go to use it I forget the details for doing some basic operations.

Sample Data

[
    {
        "name": "Homer Simpson",
        "occupation": "Nuclear Safety Inspector"
    },
    {
        "name": "Marge Simpson",
        "occupation": "Mayor"
    },
    {
        "name": "Milhouse Van Houten",
        "occupation": "Student"
    },
    {
        "name": "Homeboy Van Somebody",
        "occupation": "Lawyer"
    }
]

Filtering

Often you will have json and you’ll want to filter out all objects that do not meet some criteria.

Selecting objects with a specific value

❯ jq '.[] | select (.name == "Homer Simpson")' sample.json 
{
  "name": "Homer Simpson",
  "occupation": "Nuclear Safety Inspector"
}

Outputting a new JSON object based on the input data

❯ jq '.[] | select (.name == "Homer Simpson") | {character_name: .name, job: .occupation}' sample.json 
{
  "character_name": "Homer Simpson",
  "job": "Nuclear Safety Inspector"
}

Using a regex

❯ jq '.[] | select (.name | test("Home"))' sample.json 
{
  "name": "Homer Simpson",
  "occupation": "Nuclear Safety Inspector"
}
{
  "name": "Homeboy Van Somebody",
  "occupation": "Lawyer"
}