BMOS - Basic Multi-purpose Operating System Shell

A lightweight, interactive shell implementation written in Rust that provides command execution, built-in utilities, and advanced shell features.

Features

• Interactive Command Line: User-friendly shell interface with a command prompt
• Built-in Commands: Implements essential shell utilities including:
  • cd - Change directory
  • echo - Print text
  • pwd - Print working directory
  • exit - Exit the shell
  • type - Display command type information
  • jobs - Manage background processes
• Command Completion: Intelligent command and path auto-completion
• Background Execution: Support for running commands in the background
• I/O Redirection: Output configuration and redirection capabilities
• Error Handling: Comprehensive error management with helpful error messages
• PATH Resolution: Automatic command resolution through system PATH

Project Structure

src/
├── main.rs                 # Entry point and REPL loop
├── shell.rs               # Core shell input processing
├── runner.rs              # Command execution engine
├── input.rs               # Input parsing and tokenization
├── argument_parser.rs     # Argument parsing utilities
├── builtin_command.rs     # Built-in command definitions
├── check_builtin.rs       # Built-in command detection
├── order.rs               # Command order/execution structure
├── output.rs              # Output handling
├── output_config.rs       # Output redirection configuration
├── path_finder.rs         # PATH environment variable resolution
├── completion.rs          # Shell completion integration
├── command_completer.rs   # Command name completion
├── path_completer.rs      # Path completion
└── error/
    ├── mod.rs            # Error module definitions
    └── not_found.rs      # Command not found errors

Building

Prerequisites

• Rust 1.70+ (2021 edition)
• Cargo

Compile

cargo build --release

The compiled binary will be available at target/release/bmos.

Running

Start the shell:

cargo run

Once running, you can enter commands at the $ prompt:

$ echo Hello World
Hello World
$ pwd
/home/user
$ cd /tmp
$ exit

Dependencies

• rustyline (18.0.0) - Provides line editing and command history capabilities

Usage Examples

Basic Commands

$ echo "Hello from BMOS"
Hello from BMOS
$ pwd
/home/user/projects
$ cd ..
$ pwd
/home/user

Command Information

$ type cd
cd is a shell builtin
$ type ls
ls is /bin/ls

Background Execution

$ long_running_command &
$ jobs
[1] long_running_command

Development

The shell follows a modular architecture with clear separation of concerns:

• Parser: Tokenizes and validates user input
• Executor: Routes commands to appropriate handlers (built-in or external)
• Completer: Provides intelligent auto-completion
• Output Manager: Handles I/O redirection and formatting

License

This project is open source and available for modification and distribution.

Contributing

Contributions are welcome! Please feel free to submit pull requests or open issues for bug reports and feature requests.