🐚 Minishell (42 School Project)

🌟 Overview

Minishell is a simplified shell project developed as part of the 42 School curriculum. The aim of the project is to create a functional shell that mimics some of the core behaviors of popular shells like bash, while providing a solid foundation for learning about process management, input/output redirection, pipes, and system calls in UNIX-based systems.

The project focuses on replicating the basic functionalities of a shell without any bonus features, keeping the implementation minimal and adhering to specific requirements. The project encourages you to explore low-level system programming in C, making use of system calls such as fork(), execve(), pipe(), and signals handling.

✨ Features

The following functionalities are implemented:

1. 💻 Prompt display:

   • A prompt is displayed where the user can enter commands.

2. ⚙️ Command execution:

   • The shell can execute binary commands located in $PATH, similar to /bin/ls or /usr/bin/cat.

3. 🔧 Built-in commands:

   • The shell implements a few essential built-in commands:
     • echo with the -n option.
     • cd for changing the current directory.
     • pwd to print the current working directory.
     • export to set environment variables.
     • unset to remove environment variables.
     • env to display the environment variables.
     • exit to terminate the shell.

4. 🌐 Environment variable handling:

   • The shell manages environment variables and allows manipulation using built-in commands like export and unset.

5. 📄 Redirections:

   • Supports input (<) and output (>, >>) redirections for commands.

6. 🔗 Pipes:

   • Implements pipes (|), enabling command chaining by sending the output of one command to the input of another.

7. 🚨 Signal handling:

   • Handles signals for Ctrl+C, Ctrl+D, and Ctrl+\ to behave like a normal shell:
     • Ctrl+C: Sends an interrupt signal, should not terminate the shell.
     • Ctrl+D: Closes the shell when the input is empty.
     • Ctrl+\: Should do nothing.

8. ❗ Error handling:

   • Proper error messages are displayed for invalid commands, file access issues, or command execution problems.

🚫 Not Implemented (No Bonus Features)

The following bonus functionalities are not included in this version:

• Logical operators (&&, ||).

📋 Requirements

• Language: C (with allowed standard libraries such as unistd.h, fcntl.h, stdio.h, signal.h, etc.)
• Operating System: Linux-based (preferably tested on macOS or Linux).
• Compiler: cc with the following flags:
  • -Wall -Wextra -Werror

Installation 📦

To compile and test Minishell, follow these steps:

1. Clone the repository:

   git clone git@github.com:AnnLvu/minishell_42.git
   cd minishell_42
   

🚀 Usage

make        # Compiles the minishell library ⚒️
./minishell # Run the shell 
make clean  # Cleans up object files 🧹
make fclean  # Full cleanup of generated files 🧼
make re     # Rebuild everything from scratch 🔄

📄 Example Commands

# Running a command in $PATH
ls -l

# Redirection
cat < input.txt > output.txt

# Piping
ls | grep minishell

# Built-ins
pwd
export VAR=value
echo $VAR
unset VAR
env
exit

🎯 Conclusion

This project provides a basic yet functional shell that introduces you to the inner workings of a command-line interface, process control, and system-level programming. Through the implementation of minishell, you'll gain a deep understanding of how shells work at the fundamental level, focusing on essential UNIX system calls and process management.