Use the jq tool to process JSON data in Shell command lines.

Use the jq tool to process JSON data in Shell command lines.

Because I recently want to process some JSON data formats, after some searches early in the morning, I finally found jq, a great tool. Jq allows you to operate JSON directly on the command line, including sharding, filtering, conversion, and so on.

Install jq on mac and use brew install jq. If homebrew is installed on ubuntu, you can use sudo apt-get install jq to install jq.

Let's use several examples to illustrate jq's functions:
I. Output formatting and beautiful printing results
If we use a text editor to open JSON, it may sometimes look messy, but the JSON format can be adjusted immediately through the jq. (DOT) filter.
1. How it looks after it is opened in a text editor

2. Use the result displayed by jq to check json in the terminal!

$ jq . package.json {  "scripts": {    "test": "grunt test"  },  "engines": {    "node": ">=0.10.0"  },  "devDependencies": {    "karma-ng-html2js-preprocessor": "^0.1.0",    "karma": "^0.12.19",    "grunt-karma": "^0.8.3",    "karma-ng-scenario": "^0.1.0",    "time-grunt": "~0.2.1",    "load-grunt-tasks": "~0.4.0",    "jshint-stylish": "~0.1.3",    "grunt-usemin": "~2.0.0",    "grunt-svgmin": "~0.2.0",    "grunt-rev": "~0.1.0",    "grunt-ngmin": "~0.0.2",    "grunt-newer": "~0.6.1",    "grunt-contrib-connect": "~0.5.0",    "grunt-contrib-concat": "~0.3.0",    "grunt-contrib-compass": "~0.7.2",    "grunt-contrib-clean": "~0.5.0",    "grunt-concurrent": "~0.5.0",    "grunt-bower-install": "~1.0.0",    "grunt-autoprefixer": "~0.4.0",    "grunt": "~0.4.1",    "grunt-contrib-copy": "~0.4.1",    "grunt-contrib-cssmin": "~0.7.0",    "grunt-contrib-htmlmin": "~0.1.3",    "grunt-contrib-imagemin": "~0.3.0",    "grunt-contrib-jshint": "~0.7.1",    "grunt-contrib-uglify": "~0.2.0",    "grunt-contrib-watch": "~0.5.2",    "grunt-google-cdn": "~0.2.0"  },  "dependencies": {},  "version": "0.0.0",  "name": "myyo"}

Ii. Quick query of JSON data

Jq can be used as a keyword to quickly query JSON. For example:

$ jq .version package.json "0.0.0"

Jq key query also supports chained calling, such:

$ jq .scripts.test package.json "grunt test"

3. jq MPs queue operations

Anyone familiar with command lines may know that | (pipeline) is a very powerful weapon. Fortunately, jq also provides support for pipelines.

$ jq '.devDependencies|{ karma }' package.json {  "karma": "^0.12.19"}

Here, we use pipelines to filter and construct the karma object.

Iv. Summary
If you need to process JSON in the command line, I strongly recommend jq. Jq not only meets common general requirements, but also provides powerful functions such as computation, built-in functions, condition comparison, variable declaration, and custom functions. For more information, see the official jq manual.
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