Minishell

A hell project from 42

🌟 Features

• Interactive shell with basic prompt functionality
• Execution of binary commands (e.g., /bin/ls)
• Built-in commands:
  • cd: Change the current working directory
  • echo: Display a line of text
  • env: Show environment variables
  • exit: Exit the shell
  • export: Set environment variables
  • pwd: Print the current directory
  • unset: Remove environment variables
• Input and output redirection (<, >, >>)
• Support for pipes (|) to chain commands
• Signal handling for Ctrl+C, Ctrl+D, and Ctrl+Z
• Environment variable expansion (e.g., $PATH, $HOME)
• Error handling for invalid commands or syntax

📂 Project Structure

/minishell
├───inc
|   ├───ft_printf.h
|   ├───get_next_line.h
|   ├───libft.h
|   └───minishell.h
├───libft
|   └───...//soon will publish libft libraries
├───shell
|   ├───builtins
|   |   ├───cd.c
|   |   ├───echo.c
|   |   ├───env.c
|   |   ├───exit.c
|   |   ├───export.c
|   |   ├───pwd.c
|   |   └───unset.c
|   ├───env
|   |   ├───env.c
|   |   ├───get.c
|   |   ├───shlvl.c
|   |   └───sort.c
|   ├───exec
|   |   ├───bin.c
|   |   ├───builtin.c
|   |   └───cmd.c
|   ├───parse
|   |   ├───expansion.c
|   |   ├───line.c
|   |   ├───token.c
|   |   └───token_data.c
|   └───utils
|       ├───expansion.c
|       ├───fd.c
|       ├───free.c
|       ├───gnl.c
|       ├───minishell.c
|       ├───parse.c
|       ├───token.c
|       ├───type.c
|       └───utils.c
├───src
|   ├───main.c
|   ├───rd_cmd.c
|   └───signalling.c
├───Makefile
└───README.md

🎓 Learning Objectives

• Understanding process creation and management (fork, execve, wait, pipe)
• Mastering file I/O and redirections
• Implementing a custom shell environment
• Handling user input and signal interruptions

🤝 Collaborator

@nizarsyahmi37 - Main contributor, bash interface designer @ninetendo59 - Create minishell "skeletal" structure, norminette checking, debugging completed code (fixing leaks, uninitialised value, refactor and restructure code), sanity testing.

🤔 What is the difference between Shell and Terminal?

🖥️ Terminal

• A window or interface that provides a space to execute commands via a shell.
• Acts as a container for the shell to run.

🐚 Shell

• It is a command interpreter or environment where you execute commands.
• Offers scripting, command history, and access to system features.

⚖️ Choice of function for taking input

Function	Pros	Cons
get_next_line(int fd)	zero leaks (if you implement it correctly) mutex based recycle and minor code modification efficient, which designed to be directly take input from fd. customisible in terms on BUFFER_SIZE control	Unable to use history and require to implement history by your own low level control, which may require extra and tedious implementation.
readline (const char *prompt)	Easy usage. high level control, which is user friendly, offers line by line input reading. Thread safe, as it handles input buffer internally.	Causes leaks (Minishell project does not requires you to handle the leaks, but other leaks that is not caused by this function is not tolerated) performance wise may not be optimised for low level or socker i/o.

• In my opinion, using readline() is the easiest way to complete your minishell compared to get_next_line().
• If you are perfectionist, why not just go ahead to use get_next_line()?

⍼ Leak Check command

valgrind --leak-check=full ./minishell

📖 Further references

1. https://m4nnb3ll.medium.com/minishell-building-a-mini-bash-a-42-project-b55a10598218
2. https://www.youtube.com/watch?v=yTR00r8vBH8
3. https://medium.com/@muxanz/how-the-shell-works-internally-when-entering-a-command-42f08458870
4. https://medium.com/@nyangaresibrian/simple-shell-b7014425601f
5. https://42-cursus.gitbook.io/guide/rank-03/minishell