cshell

Screen.Recording.2026-07-05.at.2.46.34.PM.mov

A POSIX-style shell written from scratch in Go, built around one idea: most of the time, the argument you are about to type is already printed on your screen. cshell captures everything commands print and lets you grab any of it into the current command line with a keystroke.

The grab feature

Press Ctrl+G while typing a command: a fuzzy picker opens over every token from previous command output. Type to filter, arrows to choose, Enter to insert it at the cursor. No more mouse-selecting a filename out of ls output or retyping a container id.

This works because every command runs on a shell-owned pseudo-terminal (the tmux model): commands see a real tty — colors, isatty, window size, working /dev/tty for pagers and editors — while the shell mirrors all output to your screen and into a scrollback buffer that feeds the picker.

Everything else

• Hand-written lexer (POSIX quoting, escapes, fd redirects, # comments) and Pratt-style parser producing an AST
• Pipelines over real OS pipes, && / || / ;, redirects (>, >>, <, 2>, 2>&1), exit-status tracking
• Line editor built on raw mode: emacs keybindings, horizontal scrolling, PS2 continuation for unclosed quotes
• Persistent history with ↑/↓ and Ctrl+R reverse incremental search
• Tab completion: builtins and PATH commands for the first word, file paths elsewhere, ~ aware
• ~/.cshrc startup file, shell variables, export, and PS1/PS2 prompts with bash-style escapes (\u \h \w \W \$ \e ...) including colors
• Tilde expansion in arguments and redirect targets, quote-aware

Install

One-liner (Debian / Ubuntu & macOS)

curl -fsSL https://iam-abdul.github.io/cshell/install.sh | sudo sh

On Debian/Ubuntu this sets up the signed apt repository and installs cshell, so future updates come through sudo apt upgrade. On macOS it installs the prebuilt binary for your architecture into /usr/local/bin (re-run the command to update).

Debian / Ubuntu — manual apt setup

If you would rather add the repository yourself instead of piping a script:

curl -fsSL https://iam-abdul.github.io/cshell/key.gpg \
  | sudo gpg --dearmor -o /usr/share/keyrings/cshell.gpg
echo 'deb [signed-by=/usr/share/keyrings/cshell.gpg] https://iam-abdul.github.io/cshell stable main' \
  | sudo tee /etc/apt/sources.list.d/cshell.list
sudo apt update && sudo apt install cshell

Prebuilt binary (Linux / macOS)

Grab the archive for your OS/arch from the latest release, extract it, and put cshell on your PATH.

Run it

go run ./app

Piped input (echo 'ls | wc -l' | cshell) uses a plain non-interactive loop, so it scripts fine too.

Tests

go test ./app/

Unit tests cover the lexer, parser, executor, line-editor state machine, history, completion, scrollback, and picker. Integration tests drive the real compiled binary under a pseudo-terminal, typing keystrokes and asserting on what the terminal shows — including opening and quitting man, tab completion, Ctrl+R search, and the grab picker.

Not there yet

$VAR expansion, globbing, job control (&, fg), heredocs, subshells.