Abigail alludes to the two edged sword of Unix, there are no required or standardized application installers across all flavors. While this may seem weird and complicated to many users coming from a windows back-end -- it frees us from having systems tied to a registry like nightmare. For instance if I install a ton of programs on my /export partition and localize the dependent files in that partition I can completely wipe the disk (except for that partition) and start over anew with a clean install, mount the /export partition and have all my apps back without worrying about reinstalling them to appease the registry settings. With this freedom comes the cost that administrating these machines requires a larger knowledge base than windows boxes.