MP-Shell

About the Project

This project implements a POSIX-compliant interactive and minimalist shell, designed to interpret shell commands, execute external programs, and provide support for various builtin commands. It also implements advanced features such as input/output redirection and support for single and double quote handling.

The goal is to create a lightweight and flexible experience while maintaining compatibility with POSIX standards, making the shell ideal for learning and experimentation.

Installation

To install the shell, run the following command in your terminal:

curl https://raw.githubusercontent.com/MarlonPassos-git/mp-shell/refs/heads/master/install.sh | bash

Important

Currently, the shell is only available for Linux systems. Support for other operating systems may be added in the future.

Usage

After installing the shell, you can run it by typing mp-shell in your terminal. The shell will start in interactive mode, allowing you to enter commands and see the output.

$ mp-shell

Builtin Commands

Below is the list of builtin commands implemented in the shell or planned for future implementation:

Command	Description	Usage Example	Status
exit	Terminates the shell execution with the specified status code.	exit 0	✅
echo	Prints the provided arguments to the terminal.	echo hello world	✅
type	Displays how the shell interprets a command.	type echo	✅
pwd	Prints the current working directory.	pwd	✅
cd	Changes the current working directory.	cd /usr/local/bin	✅
Output Redirection (1>)	Redirects the output of a command to a file.	echo "Hello World" > file.txt	✅
Error Redirection (2>)	Redirects error messages to a file.	ls nonexistent 2> error.txt	✅
Append Output (1>>)	Appends the output of a command to the end of a file.	echo "More text" >> file.txt	✅
Append Error (2>>)	Appends error messages to the end of a file.	ls nonexistent 2>> error.txt	✅
:	A null command that does nothing but expand arguments and perform redirections.	: [arguments]	🛠️
.	Reads and executes commands from a specified file in the current shell environment.	. filename [arguments]	🛠️
eval	Concatenates arguments into a single command, then executes it.	eval [arguments]	❌
exec	Replaces the shell with the specified command without creating a new process.	exec [-cl] [-a name] [command]	❌

Note

Note: There are other commands considered builtins in Bash, as listed in the Bash Builtins Manual. However, since this is primarily a learning project, these are unlikely to be implemented.

Advanced Features

• Support for single and double quotes: Preserves literal values or interprets special characters, respectively.
• External program execution: Locates and executes external programs using the PATH.

Examples:

$ echo "Text with 'single quotes' and \"double quotes\""
Text with 'single quotes' and "double quotes"

Codecrafters Challenge

This shell project is part of the Codecrafters Shell Course. The course provides a guided journey to build your own shell from scratch, offering an in-depth understanding of shell functionalities and POSIX compliance.

If you're interested in taking the course, you can use my referral link to join: https://app.codecrafters.io/r/witty-leopard-861910.