🔧 Shell From Scratch in go

A POSIX-compliant shell implementation written in Go from scratch.

✨ Features

• Command execution with argument parsing
• Pipeline support (cmd1 | cmd2 | cmd3)
• I/O redirection (>, >>, 2>, 2>>)
• Built-in commands: cd, pwd, echo, exit, type, history
• Command history with file persistence
• Tab completion with prefix matching
• Rich line editing (powered by readline)
• Quote handling (single/double)
• Home directory expansion (~)

🚀 Installation & Running

Prerequisites

# Install Go 1.24 or higher
go mod download

Quick Start

# Run the shell using the provided script
./your_program.sh

# Interactive shell will start (type 'exit' to quit)
$ echo "Hello World!"
$ ls -la
$ pwd

🛠 Technical Concepts

• Command Processing

  • Lexical analysis and token parsing
  • Advanced quote and escape handling
  • Multi-stage pipeline execution with buffering
  • Process spawning and lifecycle management

• Shell Features

  • File descriptor management for I/O redirection
  • History with readline integration
  • Tab completion using prefix matching

• Go Specifics

  • Goroutines for concurrent command execution
  • Sync primitives (WaitGroup, Mutex)
  • Standard library syscall integration

Project Structure

app/
├── main.go         # Core shell implementation
├── read_env.go     # Environment and PATH handling
├── history.go      # History management
└── autocomplete.go # Completion engine

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Built as part of the "Build Your Own Shell" challenge on CodeCrafters.