How to update Xcode to install "UNIX Development Support"?

Question

I installed Xcode a long time ago.

Apparently I didn't check back then the "UNIX Development Support" checkbox.

Now I want to have them but when I click on the installation this is what appears:

The UNIX Development Support check box is disabled

Q: How can I install the UNIX Development Support? Is there a way to run some script that creates all the needed links from /Developer/ to /usr/bin ?

EDIT: Note: This is for old Xcode 3. Screens and tool names differ for Xcode 4 ("Unix Command Line Tools")

Answer 1

With Xcode 4.3 (from Apple App Store) you can enable Unix Command Line Tools via the Xcode Menu: Preferences -> Download -> Components