What is Grunt for?
Grunt is basically a build / task manager written on top of NodeJS. I would call it the NodeJS stack equivalent of ANT for Java. Here are some common scenarios you would want to use grunt under:
- You have a project with javascript files requiring minification, and generally generating a front end build seperately (in case you're using say JAVA for your backend). (grunt-contrib-uglify)
- When you save code on your machine during development, you want the browser to reload your page automatically (might seem like a small thing, but believe me this has saved me lots of time). (Live reload)
- When a developer saves code on his machine, he wants a comprehensive list of JS errors / general best practice violations to be shown. (grunt-contrib-jshint)
- You have a project with SASS/ LESS files which need to be compiled to CSS files on the developers machine during development, For example whenever he saves a SASS file, you want it to be compiled to a CSS file automatically, for inclusion in your page. (grunt-contrib-sass)
- You have a team of front end developers who're working on the UI, and a team of backend developers working on the backend, you want the front end devs to use the backend REST API's without having to compile & deploy code everytime on their own machines. In case you were wondering, this isn't possible with a typical web server setup because XHR isn't allowed to be cross-domain by browser. Grunt can setup a proxy for you redirecting XHR requests on your own system within the grunt connect server to another system! (grunt-contrib-proxy, grunt-contrib-connect)
I do not think your shell script can do ALL of these. To summarize, yes, setting up a Gruntfile.js is tedious for someone who has had little exposure to javascript / is new to nodeJS, I went through the same pains as a learner, but Grunt is an amazing piece of software. DO invest the time to setup a proper Gruntfile.js for your front end project, and you'll thank god for making your life a lot easier :)
The Advantage vs shell script:
If you write shell script for every one of these tasks, it is tedious to maintain and then customize for every one of your needs. Gruntfile.js is actually pretty easy. there is a config that you init it with, specifying what tasks you want to perform, the sources and targets for each.
The integration with project seed generators on Yeoman, Gulp is another major factor to consider. Yeoman and Gulp come with Gruntfile.js' with intelligent defaults. For someone who is the sole UI contributor on his team, this is priceless to me!
For someone who is working on frontend technologies, if you have more than one person working with you, its rather easy for them to get to know Grunt, which is already well documented with a lot of answers on SO, than to get to know your shell scripts. This might be a factor in large teams.
The numerous plugins for Grunt extend base functionality. Unless your shell script is VERY popular, and VERY modular, I dont see plugins being built for it. This also extends to inclusion of new front end technologies in your project. Say, if you want to use typescript in your project tomorrow, your shell script will need to incorporate this and account for it with your own effort. With Grunt, its just as simple as "npm install " and adding a config.
Even though I agree with most advantages pointed in Accepted Answer, I still have to consider the disadvantages that are highlighted by Keith Cirkel in Why we should stop using Grunt & Gulp
Thus, some advantages are rebut by Grunt overheads and at least you should consider all this in your final decision of using Grunt, or not.