to "rice" a system you are often changing a lot of "dot files", hidden configuration files on your system which begin with a period in the name. having a bunch of dots (like rice) is descriptive but also can be a reference to a racist term used about tuning asian vehicles.
when linux users use it they're usually just referring to a bunch of altered configuration files which are generally dot files. thus, a rice. but im not sure the term would exist if the racist term hadn't already.
im not sure the term would exist if the racist term hadn’t already.
It definitely wouldn't. That's not really a term that occurs "organically" in computer language. "Rice" has nothing to do with computers, so it would have had to come from somewhere else.