Minishell

Introduction

Minishell is a simplified version of a Unix shell, developed as part of the 42 school curriculum. The project aims to create a basic shell that can execute commands, manage processes, and handle signals, mimicking some of the core functionalities of Bash or other Unix-like command-line interpreters. The project was made possible thanks to the contribution of fgori; I personally took care of the parsing part and the signal management, while my colleague contributed to the development of the executor.

Table of Contents

• Minishell
  • Introduction
  • Table of Contents
  • Features
  • Installation
  • To compile Minishell, follow these steps:
  • Usage
  • Built-in Commands
  • External Commands
  • Signal Handling
  • Project Requirements
  • Testing
  • Contributing
  • License

Features

• Command execution with arguments: Run commands with options (e.g., ls -la).
• Input and output redirection: Support for <,<<, and >>, > operators.
• Piping: Connect the output of one command to the input of another using |.
• Environment variable handling: Use and manage environment variables (e.g., $VARIABLE).
• Basic signal handling: Proper management of signals such as Ctrl+C, CTRL+\ and Ctrl+D .
• Built-in commands: Includes essential commands like echo, cd, pwd, export, unset, env, and exit.
• Error handling: Displays appropriate error messages for invalid inputs and commands.

Installation

To compile Minishell, follow these steps:

1. Clone the repository:

   git clone https://github.com/yourusername/minishell.git

2. Navigate to the project directory:

   cd minishell

3. Build the project using make:

   make

   This will generate an executable named minishell.

Usage

To start the shell, run the following command: ./minishell

$ pwd
/home/user/minishell

$ echo "Hello, World!"
Hello, World!

$ ls -la | grep minishell
-rwxr-xr-x  1 user  user  40960 Aug  9 12:00 minishell

$ export MY_VAR="42"
$ echo $MY_VAR
42

$ exit

Built-in Commands

Minishell includes several built-in commands that are executed within the shell process:

• echo [args]: Prints the arguments to the standard output.
• cd [directory]: Changes the current directory.
• pwd: Prints the current working directory.
• export [name[=value]]: Sets or exports an environment variable.
• unset [name]: Unsets an environment variable.
• env: Prints the environment variables.
• exit [status]: Exits the shell with an optional status code.

External Commands

For commands that are not built-in, Minishell searches for the executable in the directories listed in the PATH environment variable. It then creates a child process using fork() and executes the command in the child process using execve().

Signal Handling

Minishell handles the following signals:

• SIGINT (Ctrl+C): Interrupts the current command and returns to the prompt without exiting the shell.
• SIGQUIT (Ctrl+): Ignored.
• EOF (Ctrl+D): Exits the shell if the prompt is empty.

Project Requirements

Minishell meets the following requirements set by the 42 school:

• No memory leaks, invalid reads/writes, or other memory issues (tested with valgrind).
• No use of external libraries other than those specified by the project guidelines.
• Proper handling of edge cases and errors, including invalid commands, permissions issues, and more.
• The shell works correctly with various test cases, as defined by the 42 school project.

Testing

To test Minishell, you can manually run various commands to ensure correct behavior. You can also use tools like valgrind to check for memory issues:

valgrind --leak-check=full ./minishell

Contributing

Contributions are welcome! If you find any bugs or have suggestions for improvements, please feel free to open an issue or submit a pull request.

License

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