Installing other os (Ubuntu in this article) on ps3 is a super easy thing to do, just download the iso and follow the instruction on this site http://psubuntu.com/, switching back to the original os is also as simple as boot-game-os, But there may be a time where you might have an error, and if the error goes something like /usr/sbin/ps3-flash-util: not found, you might want to consider the following steps to fix it:
* type sh
* /usr/sbin/boot-game-os
Thats all, on my ps3, there were an error that the system was reading boot-game-os from /sbin while its reading the ps3-flash-util from /usr/sbin and it so happen that boot-game-os from /usr/sbin is reading the ps3-flash-util from the same folder.
Hope this helps
