Minishell

As beautiful as a shell

Summary

Minishell is a project designed to create a minimal shell (like Bash), allowing users to interact with a computer through command-line input. It provides an opportunity to explore process management, file descriptors, signal handling, and many other low-level programming concepts.

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Features

Mandatory Features

• Interactive Prompt: Displays a prompt and waits for user commands.
• Command Execution: Executes commands using the PATH environment variable or relative/absolute paths.
• History Management: Keeps track of previously executed commands.
• Quoting System:
  • Single quotes (') prevent interpretation of meta-characters.
  • Double quotes (") prevent interpretation except for $.
• Redirections:
  • <: Redirects input.
  • >: Redirects output.
  • <<: Reads input until a given delimiter (heredoc).
  • >>: Redirects output in append mode.
• Pipes: Implements pipelines to connect the output of one command to the input of another (e.g., ls | grep file).
• Environment Variables: Handles variables starting with $ and supports $? for the last exit status.
• Signal Handling:
  • Ctrl+C: Displays a new prompt.
  • Ctrl+D: Exits the shell.
  • Ctrl+\: Does nothing.
• Built-in Commands:
  • echo: Prints to standard output.
  • cd: Changes the current directory.
  • pwd: Prints the current directory.
  • export: Sets environment variables.
  • unset: Unsets environment variables.
  • env: Prints all environment variables.
  • exit: Exits the shell.

Bonus Features

The bonus features will only be evaluated if the mandatory part is perfect.

• Logical operators (&& and ||) with support for parentheses.
• Wildcard (*) support for the current working directory.

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Requirements

• Programming Language: C
• External Libraries:
  • Readline
• System Calls:
  • fork, execve, pipe, dup2, read, write, open, close, kill, etc.
• Code Norms: Follow the 42 Norm.

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Installation

1. Clone the repository:

   git clone https://github.com/oelbouha/minishell 
   cd minishell  

Compile the project:

bash make
Run the shell:

bash ./minishell
Usage Launch the shell using the above steps. Use standard commands like ls, pwd, or any custom-built commands. Test features like redirections, pipes, and environment variable expansion. Examples:

bash

echo "Hello, Minishell!"
Hello, Minishell!

ls | grep minishell
minishell.c

export VAR=42
echo $VAR
42
Project Structure

minishell/
├── Makefile # Build script
├── src/ # Source code files
│ ├── main.c # Entry point for the shell
│ ├── parser.c # Handles command parsing
│ ├── executor.c # Executes commands
│ ├── builtins.c # Implements built-in commands
│ ├── signals.c # Signal handling
│ └── utils.c # Utility functions
├── include/ # Header files
│ ├── minishell.h # Main header file
│ └── ...
└── libft/ # 42's Libft library (if used)
Key Concepts Processes: Mastering fork, execve, and managing process hierarchies. File Descriptors: Redirections and pipes are based on file descriptor manipulation. Signal Handling: Handling user interrupts like Ctrl+C gracefully. Memory Management: Ensuring no memory leaks using tools like valgrind. Challenges Faced Parsing commands with quotes and special characters. Managing multiple processes in a pipeline. Handling edge cases for built-in commands and redirections. Resources GNU Readline Documentation Linux System Calls