Custom Unix Shell 🐚

A lightweight, Unix-like command-line shell built in C as part of the CodeCrafters Unix Shell challenge. This shell provides a seamless and user-friendly command-line experience, featuring built-in commands, robust input parsing, file redirection, history management, and autocompletion. 🚀

Features 🌟

• Built-in Commands 💻

  Supports common shell commands, including:

  • cd (Change directories)
  • echo (Display messages)
  • exit (Quit the shell)
  • and more!

• External Command Execution 🏃‍♂️

  Executes standard Unix commands by forking and managing child processes.

• Input Parsing 🔍

  Smart handling of:

  • Quoted strings ("text")
  • Escape sequences (e.g., \n, \t)
  • Arbitrary whitespace
  • Edge cases in user input (no command left behind!)

• File Redirection 📂

  Supports output (>), and append (>>) redirection.

• Piping Support 🔗

  Enables command chaining using the pipe operator (|). Output from one command can be seamlessly passed as input to the next.

• Command History ⏳

  Tracks your executed commands and allows you to easily recall and reuse them. No more typing the same thing twice!

• Autocompletion ⌨️

  Tab-based autocompletion for commands, file paths, and more for an enhanced user experience.

About 👨‍💻

This project was built as part of the CodeCrafters Unix Shell challenge. The goal? To implement a shell from scratch in C and dive deep into system-level programming. While certain parts could be optimized using existing libraries, I decided to implement them myself for the maximum learning experience. 💡

Installation ⚙️

1. Clone the repository:

   git clone https://github.com/Kaston-C/shell.git
   cd shell

2. Install dependencies (make sure you have gcc or another C compiler installed):

   • On Debian-based systems (Ubuntu, etc.):

     sudo apt-get install libreadline-dev

   • On macOS (using Homebrew):

     brew install readline

3. Run the shell (compiles and runs the shell):

   ./start.sh

Usage 🎮

Once the shell is running, you can:

• Execute built-in or external commands
• Use redirection like ls > files.txt to capture output
• Recall previous commands with up/down arrows
• Use Tab for autocompletion of file/command names (no more typos!)

Example 📝

$ echo "Hello, Shell!"
Hello, Shell!

$ ls -la > out.txt

$ cat out.txt | grep ".c" | wc

Dependencies 📦

• C Standard Library (stdlib.h, stdio.h, string.h, unistd.h, fcntl.h, sys/wait.h, etc.)

• Readline Library (readline/readline.h and readline/history.h)

  • Installation steps above

• POSIX-compliant system (Linux, macOS)

License 📄

MIT License