If we need to display a block in user pages, and not in /user/login or /user/register etc pages, we need to field in some custom php code under the Page specific visibility settings, we select the radio "Show if the following PHP code returns TRUE (PHP-mode, experts only)" and we fill in the following code:

In this example, we will install drush under the directory /usr/local/share/. The path is not really important as long as you adjust the following commands accordingly.

If the directories do not exists, we create them:

sudo mkdir /usr/local/share/
sudo mkdir /usr/local/bin/

And now it time to download and extract drush. Make sure that you have the latest version available and replace the url in the command accordingly.

We also create a symlink so that we can use it everywhere without typing the parent path all the time...