minishell

Finished in: 2024-12-24

This project was done in partnership with José Júnior

About

This project objective is to create a simplified version of Bourne-Again Shell (Bash). It provides hands-on experience with key concepts in systems programming, such as:

• accurately parse and interpret user input, handling commands with pipes and redirections;
• implementing process creation, executing commands, and managing parent-child process communication;
• supporting input and output redirection and piping between two or more commands;
• handling signals to manage process termination and keyboard interrupts properly;
• manage memory dynamically, ensuring proper allocation and deallocation, avoiding memory leaks, and handling errors.

Features

The mandatory part consists of:

• Handling ’ (single quotes) which should prevent the shell from interpreting the metacharacters in the quoted sequence.
• Handling " (double quote) which should prevent the shell from interpreting the metacharacters in the quoted sequence except for $ (dollar sign).
• Implementing pipes | and redirections for input <, output >, output in append mode >> and heredoc <<.
• Handling environment variables ($ followed by a sequence of characters) which expand to their values; and $? which expands to the exit status of the most recently executed foreground pipeline.
• Handling the behavior of ctrl-C, ctrl-D and ctrl-\ like in bash. And in interactive mode: ctrl-C displays a new prompt on a new line; ctrl-D exits the shell; ctrl-\ does nothing.
• Implementing the builtins: echo with option -n; cd with only a relative or absolute path; pwd with no options; export with no options; unset with no options; env with no options or arguments; and exit.

And the bonus part consist of the additional:

• Handling the logic operators && and || with parentheses for priorities.
• Wildcards * for the current working directory.

The minishell program does not interpret unclosed quotes, unclosed parentheses or any special characters that are not required by the subject such as \ (backslash), ; (semicolon) or ~ (tilde).

Build

Clone the repository:

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

Enter the cloned directory:

cd minishell

Run make to compile the program:

make bonus

Usage

Start the program:

./minishell

Insert input, like you would in bash:

ls -la

export VAR=test && echo $VAR

cd .. && pwd

The Norm

This project is written in accordance to the 42 School's "The Norm" (Version 4). To review the Norm, click here.

Contributions

If you find any issues or have suggestions for improvements, please feel free to open an issue or submit a pull request.

Message to students

If you are searching resources to learn more about your own minishell, I encourage you to turn to your peers and the function manuals. Do not implement any code you do not understand and cannot code from scratch.