🚀 SYNOPSIS

The minishell project at 42 school immerses students in the dynamic world of UNIX shell development within the C language. This comprehensive undertaking requires a deep understanding of system calls, process management, and parsing techniques.

Students are tasked with crafting a minimalistic shell that mimics the fundamental functionalities of a UNIX command-line interface.

Beyond basic command execution, minishell delves into advanced features such as environment variable handling, signal management, and piping. Leveraging knowledge in lexical analysis and parsing, students navigate the intricacies of command interpretation and user interaction.

This project, interwoven with the philosophy of simplicity and efficiency, not only sharpens skills in system-level programming but also imparts a practical understanding of the core components that constitute a fully functional shell.

🛠️ PROGRAM SPECIFICITIES AND CONSIDERATIONS

Start by clonning the repo :

git clone git@github.com:maitreverge/minishell.git && cd minishell

Important

The program must replicate the behavior of a shell in interactive and non-interactive modes, following the project’s strict guidelines.

Warning

Undefined behavior, such as unclosed quotes or incorrect handling of special characters, should be avoided.

The program should:

• Display a prompt when waiting for user input.

• Execute commands found in the PATH or using absolute/relative paths.

• Handle errors gracefully and display appropriate messages.

• Implement built-in commands as specified in the subject.

⚙️ USAGE

The primary program is called minishell, and it will be compiled using:

make

The program can be executed as follows:

./minishell

Upon execution, it should display a prompt and allow the user to enter commands. For example:

minishell$ ls -l

Output:

total 8
-rw-r--r-- 1 user user 1024 Jan 15 2025 file1.txt
-rw-r--r-- 1 user user 2048 Jan 15 2025 file2.txt

🔧 CORE FEATURES

The program implements the following core functionalities:

Command Execution

• Search and execute commands based on the PATH environment variable or absolute/relative paths.

Built-in Commands

The following built-in commands must be implemented:

• echo: Prints text to the terminal. Supports the -n option to suppress the newline.

• cd: Changes the current directory.

• pwd: Prints the current working directory.

• export: Sets or updates environment variables.

• unset: Unsets environment variables.

• env: Displays the current environment variables.

• exit: Exits the shell.

Redirections

• <: Redirect input from a file.

• >: Redirect output to a file.

• <<: Implement heredoc functionality.

• >>: Append output to a file.

Pipes

• Handle pipelines |, chaining multiple commands together so the output of one becomes the input of the next.

Signal Handling

• Ctrl+C: Interrupts the current command and displays a new prompt.

• Ctrl+D: Exits the shell.

• Ctrl+\: Does nothing, mimicking bash behavior.

Environment Variables

• Handle $ expansion to substitute environment variables.

• Handle $? to display the exit status of the last executed command.

💻 EXAMPLE

Here’s an example session:

minishell$ echo "Hello, World!"
Hello, World!
minishell$ pwd
/home/user/minishell
minishell$ export MY_VAR=42
minishell$ echo $MY_VAR
42
minishell$ ls | grep minishell
minishell
minishell$ exit

🧑‍💻 AUTHORS

This project was developed by the following contributors:

• George LAMBRIGHT (@glambrig) – Specialized in minishell execution (pipelines, redirections), signal handling and crafting the built-ins.
• Florian VERGE (@maitreverge) – Managed minishell parsing, environment variables and $? last exit status.

The project started in Febuary 2024 and was completed over the course of 5 weeks.

🤝 CONTRIBUTION

Contributions are open, open a Github Issue or submit a PR 🚀