If you are a new Drupal developer you must know about Drush utility. It makes your life easy when you install new modules and themes.You can install Drush in three simple steps.
STEP 1:-
Install PHP cli package.
root@dev:#apt-get install php5-cli
STEP 2:-
go to /opt directory
root@dev:#cd /opt
Download drush form the link below
root@dev:/opt#wget http://ftp.drupal.org/files/projects/drush-All-versions-4.0-rc1.tar.gz
If this link doesn't work google for new link.
unzip Drush
root@dev:/opt# tar xvfz drush-All-versions-4.0-rc1.tar.gz
STEP 3:-
root@dev:/opt# ln -s /opt/drush/drush /usr/local/bin/
Test drush
root@dev:/var/www# drush dl drupal
This command download a fresh stable version of Drupal to your Apache document root(/var/www/) and extract it.
Other Helpful links :-
official Drush Page.
http://drupal.org/project/drush
Drush cheat sheet.
http://drupal.org/node/477684