YASH - Yet Another Shell

YASH is a simplified command line interpreter written in C that demonstrates core shell functionality including process management, redirection, job control, and signal handling.

Features

Core Functionality

• Command Execution: Execute external programs and built-in commands
• Redirection: Support for <, >, and 2> (stdin, stdout, stderr)
• Pipes: Single pipe | support for command chaining
• Environment: Inherits and manages environment variables
• PATH Resolution: Finds executables via PATH environment variable

Job Control

• Background Jobs: Run processes in background with &
• Job Management: Built-in commands jobs, fg, and bg
• Job Tracking: Supports up to 20 concurrent jobs
• Process Groups: Proper process group management

Signal Handling

• SIGINT: Handles Ctrl-C for process interruption
• SIGTSTP: Handles Ctrl-Z for process suspension
• SIGCHLD: Manages child process termination

User Interface

• Prompt: Clean # prompt
• Input: Line-based command input
• Exit: Clean exit on Ctrl-D (EOF)

Architecture

The shell is organized into several key modules:

• main.c: Entry point and main shell loop
• parse.c: Command parsing and tokenization
• exec.c: Command execution and process management
• jobs.c: Job control and background process management
• signals.c: Signal handling and process control

Usage Examples

# Basic command execution
# ls -la
 
# Redirection
# echo "Hello World" > output.txt
# cat < input.txt
 
# Pipes
# ls -la | grep ".c"
 
# Background jobs
# sleep 10 &
# jobs
# fg
 
# Job control
# sleep 30 &
# jobs
# bg %1
# fg %1

Building

# Build the project
make
 
# Generate documentation
make docs
 
# Clean build artifacts
make clean
 
# Clean documentation
make docs-clean

Project Structure

YASH/
├── src/                    # Source files (.c)
├── include/                # Header files (.h)
├── build/                  # Build artifacts
│   ├── obj/               # Object files
│   └── bin/               # Executable
├── docs/                   # Documentation
│   ├── html/              # Generated HTML docs
│   ├── images/            # Documentation images
│   └── doxygen-awesome-css/ # Theme files
└── Makefile               # Build configuration