Minishell (42 Project)

Overview

Minishell is a project from the 42 curriculum where I built a simple Unix shell from scratch. The main goal for me was to understand how a shell actually works behind the scenes by implementing core features myself, such as command execution, parsing user input, and handling basic system behavior.

Instead of relying on existing shell implementations, I worked directly with low-level system calls to manage processes, file descriptors, and signals.

The project is not intended to fully replicate Bash, but rather to include the essential, commonly used features of a shell and provide a user experience that feels similar to Bash.

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Features

• Execution of commands (ls, echo, cat, etc.)

• Environment variable handling ($PATH, $HOME, etc.)

• Built-in commands:

  • echo
  • cd
  • pwd
  • export
  • unset
  • env
  • exit

• Pipes (|)

• Redirections:

  • Input (<)
  • Output (>)
  • Append (>>)
  • Heredoc (<<)

• Signal handling (Ctrl+C, Ctrl+D, Ctrl+\)

• Basic error handling (syntax and execution)

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What I learned

• Process creation and control (fork, execve, wait)
• File descriptors and I/O redirection
• Parsing and tokenization
• Memory management
• Signal handling
• General Unix system programming concepts

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Build and run

Clone the repository:

git clone git@github.com:ausperg/minishell.git
cd minishell

Compile:

make

Run:

./minishell

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Examples

$ echo Hello World
Hello World

$ export NAME=42
$ echo $NAME
42

$ cat < input.txt > output.txt

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Tech stack

• Language: C
• System calls: fork, execve, pipe, dup2, waitpid
• Standard C library and a custom libft

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Notes

This project is part of the 42 curriculum and is intended for learning purposes. It focuses on understanding core Unix behavior rather than building a production-ready shell.