The term 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 Compatible Time-Sharing System (CTSS) system.

From Brian Kernighan

Brian Kernighan

Brian Wilson Kernighan is a Canadian computer scientist who worked at Bell Labs alongside Unix creators Ken Thompson and Dennis Ritchie and contributed to the development of Unix. He is also coauthor of the AWK and AMPL programming languages. The 'K' of K&R C and the 'K' in AWK both stand for...

 and Dennis Ritchie

Dennis Ritchie

Dennis MacAlistair Ritchie , was an American computer scientist who "helped shape the digital era." He created the C programming language and, with long-time colleague Ken Thompson, the UNIX operating system...

:
"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

Unix

Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...

 is a fossil from that usage."

Tom Van Vleck

Tom van Vleck

-Life and work:He worked on CTSS at MIT, and co-authored its first email program.In 1965, he joined Project Mac, which is the origin of the MIT Computer Science and Artificial Intelligence Laboratory., Chiou, Stefanie; et. al...

, a Multics

Multics

Multics was an influential early time-sharing operating system. The project was started in 1964 in Cambridge, Massachusetts...

 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

Louis Pouzin

Louis Pouzin invented the datagram and designed an early packet communications network, CYCLADES...

 called RUNCOM, the source of the ".rc" suffix on some Unix configuration files."

This is also the origin of the name of the Plan 9 from Bell Labs

Plan 9 from Bell Labs

Plan 9 from Bell Labs is a distributed operating system. It was developed primarily for research purposes as the successor to Unix by the Computing Sciences Research Center at Bell Labs between the mid-1980s and 2002...

 shell by Tom Duff

Tom Duff

Thomas Douglas Selkirk Duff is a computer programmer. He was born in Toronto, Ontario, Canada and grew up in Toronto and Leaside. In 1974 he graduated from the University of Waterloo with a B.Math and, two years later, got an M.Sc...

, the rc shell. It is called 'rc' because the main job of a shell is to 'run commands'.

While not historically precise, rc may also be expanded as "run control", because an rc file controls how a program runs. For instance, the editor Vim

Vim (text editor)

Vim is a text editor written by Bram Moolenaar and first released publicly in 1991. Based on the vi editor common to Unix-like systems, Vim is designed for use both from a command line interface and as a standalone application in a graphical user interface...

 looks for and reads the contents of the .vimrc file to determine its initial configuration. In The Art Of Unix Programming, Eric S. Raymond

Eric S. Raymond

Eric Steven Raymond , often referred to as ESR, is an American computer programmer, author and open source software advocate. After the 1997 publication of The Cathedral and the Bazaar, Raymond was for a number of years frequently quoted as an unofficial spokesman for the open source movement...

consistently refers to rc files as "run-control" files.

External links

• In Unix, what do obscurely named commands stand for?