[2] He released a paper in 1965 describing a design for the Multics shell which includes a brief description of RUNCOM[3] followed by a second paper he released five days later describing a design for RUNCOM that added commands for control flow, conditional branching and looping.
rc in Unix is a fossil from that usage.Tom Van Vleck, a Multics engineer, has also reminisced about the extension rc: "The idea of having the command processing shell be an ordinary slave program came from the Multics design, and a predecessor program on CTSS by Louis Pouzin called RUNCOM, the source of the '.rc' suffix on some Unix configuration files.
For instance, the editor Vim looks for and reads the contents of the .vimrc file to determine its initial configuration.
When a user invoke RUNCOM, the arguments (parameters) to it must first start with the first name of the file containing the script.
CMD will be substituted into LISTF which will list the files in the directory (like the Unix ls command).
Once the substitutions have been completed, RUNCOM sends the commands to the SCHAIN library subroutine which is available to other programs as well.