RC Shell

Description #

RC is a minimalist, functional shell from the Plan 9 operating system, known for its simplicity, elegance, and consistent syntax. It was designed to overcome the inconsistencies and complexities found in traditional Unix shells.

History #

RC was developed in the late 1980s by Tom Duff at Bell Labs as part of the Plan 9 from Bell Labs project — a research operating system intended as a successor to Unix. RC stands for “run commands” and follows a clean, orthogonal design heavily influenced by functional programming principles. Though less widely used, it is appreciated by enthusiasts for its clarity and predictability.

Hello World Code #

echo 'Hello, World!'

How to Run #

Option 1: Online

• No dedicated RC shell emulator online, but some Unix VM environments support it.
• Try Plan 9 Online (9pfs) (indirect access to RC shell)

Option 2: Local

Install RC Shell (via 9base or Plan 9 packages):

sudo apt install 9base

Save the code in hello.rc and run:

rc hello.rc

Key Concepts #

1. Minimalist syntax
2. Functional, orthogonal design
3. No special characters like $ for variables
4. Uses = for assignment (no export)
5. Clean command substitution with backtick()
6. Easy-to-read and predictable syntax
7. No control structures like case, uses if and loops
8. Consistent quoting rules
9. Part of the Plan 9 OS philosophy
10. Still used in niche systems programming circles

Try It Online #

• 9p.io – Plan 9 from Bell Labs (indirect access)

Fun Facts #

• RC was designed by Tom Duff, also known for Duff’s Device in C.
• Unlike most shells, variables don’t need a $ prefix.
• RC scripts often look more like functional code than traditional shell scripts.

Resources #

• RC Man Page
• RC Shell in 9base
• Plan 9 Wiki
• RC GitHub Mirror