Egg Shell (Python)

A small, POSIX-inspired shell built for the CodeCrafters "Build Your Own Shell" challenge. It supports a set of core shell behaviors, builtins, and utilities implemented in Python.

What this shell can do

• Builtins: echo, pwd, cd, type, complete, jobs, history, declare, exit
• External commands by searching PATH
• Quoting and escapes for single quotes, double quotes, and backslashes
• Pipes with | between commands
• Redirections: >, >>, 1>, 1>>, 2>, 2>>
• Background jobs via & with jobs listing
• Tab completion for commands and file paths
• Basic variable expansion via declare and $VAR or ${VAR}
• History support (including -r, -w, -a) and optional HISTFILE

Project layout

• app/main.py: core shell implementation
• egg-shell.sh: local runner script (uses uv)

Run locally

This project uses uv to run the shell. If you do not have it installed, see https://docs.astral.sh/uv/ for installation instructions.

./egg-shell.sh

Optional: run directly with Python

If you prefer to run without uv, make sure you have Python 3.14+ available and run:

python -m app.main

Development notes

• The shell loads commands from PATH on startup.
• If HISTFILE is set, history is read and appended on exit.
• Completion specs can be registered using complete -C <path> <command>.