SimpleShell

A lightweight, feature-rich shell implementation with advanced process management capabilities.

Overview

SimpleShell is a modern, POSIX-compliant shell designed for both usability and extensibility. Built with C++, it offers a robust alternative to traditional shells with enhanced process management, customizable prompts, and intuitive job control.

Features

Powerful Process Management

• Foreground & Background Execution: Run commands in the foreground or background with the & operator
• Job Control: Pause running processes with Ctrl+Z and resume them with fg or bg commands
• Process Tracking: Comprehensive tracking of all running and stopped processes

User Experience

• Customizable Prompt: Personalize your shell experience with color-coded, dynamic prompts
• Command History: Navigate through previous commands with built-in history support
• Tab Completion: Efficiently complete commands and file paths with tab completion

Configuration

• INI Configuration: Easily customize shell behavior through simple configuration files
• Environment Variables: Set and manage environment variables with intuitive syntax
• Aliases: Create shortcuts for frequently used commands

Signal Handling

• Graceful Interruption: Properly handles Ctrl+C (SIGINT) and Ctrl+Z (SIGTSTP)
• Child Process Management: Automatically cleans up zombie processes

Getting Started

Prerequisites

• C++ compiler with C++20 support
• POSIX-compliant operating system (Linux, macOS, etc.)
• GNU Readline library

Building from Source

git clone https://github.com/fszontagh/simpleshell.git
cd simpleshell
mkdir build && cd build
cmake ..
make

Send command to Terminal

Running SimpleShell

./simpleshell

Reload configuration

$ reload_config

Send command to Terminal

Usage Examples

Basic Command Execution

$ ls -la
$ echo "Hello, world!"
$ cd ~/Documents

Background Processes

$ sleep 30 &
Running in background: sleep 30 &
Process 123456 running in background.

Job Control

$ sleep 60
^Z

$ jobs
Background jobs: 1
[1] PID: 123455 started: 2025-04-19 11:56:45.123
status: running, Command: sleep 30
Stopped jobs: 1
[1] PID: 123456 started: 2025-04-19 11:57:00.456
status: stopped, Command: sleep 60

$ bg
Continuing process 123456
Process 123456 completed.

$ fg 123457
Bringing job 123457 to foreground

Custom Prompt

# In ~/.pshell configuration
[shell]
prompt_format = "${COLOR_GREEN}[${PWD}]${COLOR_RESET}$ "

Example configuration file

[shell]
prompt_format = "${COLOR_RED}${USER}${COLOR_RESET}@${COLOR_GREEN}${HOSTNAME}${COLOR_RESET} [${PWD}]${SHELL_PROMPT} "

[environment]
HOSTNAME=`hostname`

[variables]
SHELL_PROMPT="$"

[aliases]
ls= "ls -ltrh --color=auto"
ll= "ls -ltr --color=auto"
l= "ls -ltrh --color=auto"

Architecture

SimpleShell is built with a modular architecture:

• SimpleShell: Core shell functionality, command parsing, and execution
• ProcessManager: Handles process creation, tracking, and signal management
• Configuration: Manages user preferences and environment settings

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

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

Acknowledgments

• Inspired by traditional UNIX shells like Bash and Zsh
• Built with modern C++ practices for reliability and performance

"SimpleShell: The power of a full-featured shell with the simplicity you deserve."