Rc stands for the phrase "run commands". It is used for any file that contains startup information for a command. It is believed to have originated somewhere in 1965 from a runcom facility from the MIT CTSS system. From Brian Kernighan and Dennis Ritchie, as told to Vicki Brown: "There was a facility that would execute a bunch of commands stored in a file; it was called runcom for "run commands", and the file began to be called "a runcom". rc in Unix is a fossil from that usage." [1] While not historically precise, rc may also be pronounced as "run control", because an rc file controls how a program runs. For instance, the editor vim looks for and reads the contents of the .vimrc file to determine its initial configuration. The most sensible pronunciation depends on the function of the file: to start something up, or to control how something starts up. This is also the origin of the name of the Plan 9 from Bell Labs shell by Tom Duff, the rc shell. It is called 'rc' because the main job of a shell is to 'run commands'.
