1. Install Node.js & NPM
If you already have node.js and npm installed on your system skip this step. Elase you need to install node.js on your system first. Use following set of commands to add node.js ppa in your Ubuntu system and install it.
sudo apt-get install python-software-properties curl -sL https://deb.nodesource.com/setup_8.x | sudo -E bash - sudo apt-get install nodejs
Make sure you have successfully installed node.js and npm on your system
node --version npm --version
2. Install Grunt using NPM
Now use the following command to install grunt and grunt cli using npm command line utility.
sudo npm install -g grunt
After successful installation makes sure grunt has been installed successful and check the version.
grunt --version grunt-cli v1.2.0