Funny, I came across this very same question/similar answer yesterday in "Build Awesome Command-Line Applications in Ruby 2" by David Copeland (Pragmatic Progra

Funny, I came across this very same question/similar answer yesterday in "Build Awesome Command-Line Applications in Ruby 2" by David Copeland (Pragmatic Programming, 2013): [0] "The .rc Suffix (Origin Story) Most UNIX commands use the suffix rc for the name of configuration files. According to Wikipedia, this extension isn’t an acronym for “resource configuration” or “runtime configuration” but comes from a command called RUNCOM. RUNCOM was created by Louis Pouzin for the Compatible Time-Sharing System (CTSS), which was one of the first time-sharing operating systems. RUNCOM was used to execute a series of commands in succession—a precursor to what we now call a shell script. He is even credited with coining the term shell, as he describes in a post on the Internet from 2000 on the origins of the shell: 'After having written dozens of commands for CTSS, I reached the stage where I felt that commands should be usable as building blocks for writing more commands, just like subroutine libraries. Hence, I wrote “RUNCOM”, a sort of shell driving the execution of command scripts, with argument substitution. The tool became instantly most popular [sic], as it became possible to go home in the evening while leaving behind long runcoms executing overnight. Without being invited on the subject, I wrote a paper explaining how the Multics command language could be designed with [the] objective [of using commands somehow like a programming language]. And I coined the word “shell” to name it.' Although RUNCOM (and CTSS) has long-been retired from regular use, its legacy lives on both as the name for user-specific configuration files and as the basis for the UNIX start-up scripts, typically located in /etc/rc.d." [0] https://pragprog.com/book/dccar2/build-awesome-command-line-applications-in-ruby-2 https://pragprog.com/book/dccar2/build-awesome-command-line-...