Why the cryptic rc suffix in your computer files is actually a historical ghost

Countries & Cities · Published 15 October 2026 · Updated 25 October 2026 Swipe more like this →

In short: The Unix shell is a command-line interface that powers the heart of many operating systems. While modern users often prefer graphical windows, the shell remains a vital tool for scripting and system control. Its strange naming conventions, like the rc suffix, reveal a direct lineage stretching back to 1965.

The story of the Unix shell begins with the Thompson shell, created by Ken Thompson at Bell Labs and released with early versions of Unix between 1971 and 1975. This foundational tool introduced essential concepts like piping and filename globbing. It was heavily influenced by the Multics shell, designed by Glenda Schroeder in 1965, which itself drew inspiration from a program called RUNCOM. This ancestry is preserved today in the rc suffix found in configuration files like .bashrc, a direct nod to the original RUNCOM program.

As Unix evolved, the Programmer's Workbench shell, developed by John Mashey around 1975–1977, expanded the shell's utility for large computing environments by introducing shell variables and more complex control structures. However, the most influential developments arrived with the Bourne shell, written by Stephen Bourne in 1979, and the C shell, created by Bill Joy at the University of California, Berkeley. The Bourne shell, with its characteristic dollar sign prompt, became the standard for scripting, while the C shell introduced interactive features like history mechanisms and job control, modeled after the C programming language.

Today, the landscape of shells is vast, ranging from the widely used Bourne-Again shell (bash) to the modern Z shell (zsh), which became the default for macOS in 2019 with the 10.15 Catalina release. Other variations exist outside these traditional lineages, including the object-oriented PowerShell and the Friendly interactive shell (fish), released in 2005. Whether used for simple tasks or complex automation, these shells continue to provide the command-line interface that allows users to interact directly with the operating system's core functionality.

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