MageDebugBar has only been tested with Magento 1.9, some earlier versions may work however Magento 2 does not, yet.
The composer install will create a symlink {magento root}/lib/vendor for composer based class loading (via vendor/autoload.php)
If you already have a file /lib/vendor in your Magento root then this installation will not be safe.
Note: you will need a github account as much of the code is retrieved from github and it may complain that you are requesting too much information and require your github username and password.
https://getcomposer.org/download/
Create the directory near to your Magento root. I use a directory structure like:
vhost/www - Magento root
vhost/composer - Composer files
Create a composer.json file in the composer directory
{
"prefer-stable": true,
"require": {
"bobd91/magedebugbar": "@dev"
},
"repositories": [
{
"type": "composer",
"url": "http://packages.firegento.com"
},
{
"type": "vcs",
"url": "https://github.com/bobd91/magedebugbar"
},
{
"type": "vcs",
"url": "https://github.com/bobd91/php-debugbar"
}
],
"extra":{
"magento-root-dir": "../www/"
}
}
Make sure that the "magento-root-dir" points to your Magento installation.
Then run
composer install