Drupal is one of the most famous Open Source CMS (Content management system) in the market. Powerful, easy to deploy and with lots of great modules to help you deploy any type of web platform.
So, where does Drush come in?
drush is a command line shell and scripting interface for Drupal, a veritable Swiss Army knife designed to make life easier for those of us who spend some of our working hours hacking away at the command prompt.
To put it simple, its a tool to help you maintain your Drupal installation, allowing you to easily update the core and manager your Modules.
The following info will show how you can install the latest Drush on a Ubuntu/Debian system.
Requisites:
To use Drush you need to install php5 command-line interpreter.
sudo apt-get install php5-cli
After that, Drush is ready to be installed.
Installing:
sudo wget http://ftp.drupal.org/files/projects/drush-7.x-4.4.tar.gz
sudo tar xvfz drush-7.x-4.4.tar.gz -C /opt
sudo ln -s /opt/drush/drush /usr/local/bin/
Running:
Just type drush in the Terminal and you can see all available options
sudo drush
Example : Installing Drupal Commerce
So, you have Drupal running, how does one install Drupal Commerce and dependencies?
On the Drupal installation folder (e.g. /var/www/drupal/) run the following commands:
sudo drush dl commerce
sudo drush dl addressfield ctools entity rules views
This will download and install the modules on your drupal installation. Now, to enable the modules:
sudo drush ennable addressfield ctools entity rules views
Next, you would only need to follow the Drupal Commerce instructions : http://drupal.org/node/1007434.
Basically, a time-saver!