ASH - A Simple Shell

A lightweight, feature-rich Linux shell written in Rust. ASH is designed to be portable across any Linux distribution providing essential shell functionality and modern command execution features.

Overview

ASH is a functional Unix shell implementation written entirely in Rust. It successfully handles native command execution, advanced parsing with support for pipes and operators, command history management, and simple configuration through shell scripts.

Features

Core Shell Capabilities

• Command Execution: Execute any external command with full argument passing
• Pipeline Support: Chain commands with pipes (|) for data stream processing
• Conditional Execution:
  • AND operator (&&) - Execute next command only if previous succeeds
  • OR operator (||) - Execute next command only if previous fails
• Background Processes: Run commands asynchronously with & operator
• Command History: Automatic history tracking with configurable size limits
• Interactive Prompt: Clean username@hostname:pwd$ format with home directory abbreviation

Built-in Commands

Command	Description
cd [path]	Change directory with ~ home expansion support
pwd	Print the current working directory
echo [text]	Display text with environment variable expansion
export [VAR=value]	Set environment variables persistently
unset [VAR]	Remove environment variables
alias [name=command]	Create command aliases for shortcuts
unalias [-a|name]	Remove aliases (use -a to clear all)
exit [code]	Exit the shell with optional exit code
source [file]	Execute commands from a configuration file
history	Display the command history

Configuration System

• RC File Support (.ashrc): Auto-created configuration file in the home directory
• Environment Variables: Persistent variable storage and expansion
• Custom Aliases: Define shortcuts for frequently used commands

  alias ll='ls -alF'
  alias la='ls -A'
  alias ..='cd ..'

• Shell Functions: Define and execute custom functions in configuration
• PATH Management: Full environment variable support for system path configuration

Shell History

• Automatic Tracking: All commands automatically saved to history
• Persistent Storage: History saved in .ash_history file
• Duplicate Prevention: Consecutive duplicate commands not recorded
• Configurable Limits: Default 1000-command history with customizable size
• History Retrieval: Access previous commands with history command

Advanced Features

• Variable Expansion: Automatic substitution of $VARIABLE references in commands
• Background Process Management: Monitor and track background jobs
• Exit Code Tracking: Capture and utilize exit codes for conditional execution
• Quote Handling: Support for single and double quotes in command parsing
• Escape Sequences: Handle escaped characters in command arguments
• Multi-command Processing: Parse and execute complex command chains

Getting Started

Prerequisites

• Rust 1.70+ or the 2024 edition
• Linux operating system
• Standard library dependencies: dirs, whoami

Installation

Download Binary (Recommended)

• current : ash v0.1.0-beta

chmod +x ash_v0.1.0-beta_linux-x86_64
sudo mv ash_v0.1.0-beta_linux-x86_64 /usr/local/bin/ash

Build From Source

# Clone the repository
git clone https://github.com/A55AF/ash.git
cd ash

# Build the project
cargo build --release

# Run the shell
./target/release/ash

Configuration

The shell automatically creates a .ashrc configuration file in your home directory on first run with sensible defaults including common aliases.

Example .ashrc Configuration

# ~/.ashrc - ASH Shell Configuration

# Aliases for common commands
alias ll='ls -alF'
alias la='ls -A'
alias ..='cd ..'
alias gs='git status'
alias gp='git pull'

# PATH configuration
export PATH="$HOME/.local/bin:$PATH"

# Custom environment variables
export EDITOR=vim
export TERM=xterm-256color

# Custom shell functions
greet() {
    echo "Hello, Tux! Welcome to ASH."
}

Operator Support

Operator	Behavior	Example
|	Pipe stdout to next command	ls | grep .rs
&&	Run next if previous succeeds	cd dir && ls
||	Run next if previous fails	test -f file || echo "not found"
&	Run in background	sleep 100 &

Known Limitations

• No interactive line editing or completion (future enhancement)
• Functions are limited to basic implementations
• No script scheduling or cron-like features
• Background process monitoring uses polling (marked for event-based refactor)
• No implementation for redirection (future enhancement)
• Limited Shell Scripting and configurations

Contributing

Contributions are welcome! This project is actively maintained and designed to be:

• A solid foundation for shell features
• Suitable for educational use

License

This project is licensed under the MIT License - see LICENSE file for details.