FAQ: reinstalling all packages
There is a similar entry in Pacman_Tips#Reinstalling_all_packages. The one stated in the Pacman article breaks if you've got packages installed which aren't from the repositories, e.g. AUR. The command in Pacman-Tips doesn't reinstall those. Using a Pacman & an AUR wrapper like yaourt, you can run the command from the Pacman article without a problem.
I'm new to Arch and am not going to run around editing pages in the wiki, so if anyone wants to wrap this info up in a more concise manner, I think it would be a good addition to the wiki. Maybe also a hint that the command doesn't necessarily redownload the packages as well but uses the local Pacman cache. Archlinuxomane (talk) 06:42, 21 July 2013 (UTC)