Please note: There have been updates to Drush since this video was recorded. You can learn more about installing newer versions of Drush in the blog post Upgrading Drush to work with Drupal 8. The newest version of Drush requires Composer for the installation process. If you need help getting Composer figured out, you can watch the Wonderful World of Composer video tutorial.
In this video we walk through the steps to install Drush on *nix system (i.e. Linux, Unix, or Mac OS X). Drush is not a normal Drupal project and the installation and set up is quite different than for a module. We cover requirements and downloading, then make sure Drush is executable and in our system $PATH variable so we can use Drush from any directory.
One of our members, David, offered the following tip:
I had an issue with OSX Lion and the new drush 5.0... When using the drush command the following error occurred:
/usr/bin/env: bad interpreter: Operation not permitted
This is due to Lion Quarantining the files as they are from the internet. Remove the quarantine attribute with:
xattr -d com.apple.quarantine drush
The Drush command should work now! I hope I saved someone the 2 hours of anguish this caused me.