Mini Shell (Unix-like Shell Implementation in C)

Overview

Mini Shell is a lightweight Unix-like command-line interpreter implemented in C. It supports execution of built-in and external commands, piping, signal handling, and a dynamic prompt that displays the current working directory.

This project was developed as part of advanced C and Linux systems programming practice.

Features

• Custom shell prompt (minishell:)
• Dynamic prompt showing current working directory
• Built-in commands (cd, pwd, echo, exit, etc.)
• Execution of external commands using fork() and execvp()
• Pipe (|) support
• Signal handling (SIGINT, SIGTSTP)
• Process synchronization using wait()
• Input parsing and error handling

Technologies Used

• C Programming
• Linux System Calls
• Process Management
• Signals
• File Descriptors and Pipes

Project Structure

minishell/
├── *.c
├── *.h
├── src/
│   ├── *.o
├── Makefile
├── README.md
└── .gitignore

How the Prompt Works

The shell prompt is constructed by concatenating a static identifier (minishell:) with the current working directory.

To optimize performance, the prompt is initialized before the main loop and updated only when the directory changes, i.e., after a successful cd command. This avoids unnecessary getcwd() calls on every iteration while keeping the prompt accurate.

How to Build

make

How to Run

./minishell

Sample Usage

minishell:/home/pankaj$ pwd
/home/pankaj
minishell:/home/pankaj$ cd projects
minishell:/home/pankaj/projects$ ls | grep shell

minishell:/home/pankaj/projects$ echo Hello World
Hello World

Learning Outcomes

• Understanding how Unix shells interpret and execute commands
• Hands-on experience with fork(), execvp(), and wait()
• Practical implementation of pipes and signal handling
• Improved modular programming and debugging skills
• Exposure to real-world Linux system programming concepts

Author

Pankaj Kumar B.Tech – Electronics & Communication Engineering, Embedded Systems and Linux Programming Enthusiast