This guide details how to prepare Centos 5.3 for an Oracle install. I'm running CentOS inside a VM using KVM. Since I'm setting up a test Oracle install because I'm studying for an OCA, my database needs are pretty simple. An Oracle install requires a non-trivial amount of OS prep work, so I'm writing about the experience here.
I wrote a wrapper for Oracle's sqlplus CLI that uses the Readline library. I was influenced by the excellent Sqsh interface for Sybase (and MS SQL). OSqsh (which I'm pronouncing "Oh-skwish") doesn't really do anything extra so far, except that it makes the command history available using arrow keys thanks to the GNU Readline library. That alone is pretty much the whole point of OSqsh.