MandoSHell - C Command Line Interpreter

MandoSHell is a minimalist command-line interpreter developed in C. The project implements a robust REPL (Read-Eval-Print Loop) to handle user input, argument parsing, and process execution logic.

Architecture

The system is organized into three distinct logical layers to ensure modularity and maintainability:

1. Main Loop (REPL): Manages the primary execution flow, standard input/output, and the dynamic user prompt.
2. Parser: Handles string tokenization, transforming the raw input buffer into a null-terminated argument array (argv).
3. Dispatcher: Analyzes the initial token to route execution either to an internal builtin function or to an external system binary.

Features

• Dynamic Prompting: Real-time working directory display with automatic HOME directory contraction using the tilde (~) character.
• Exit Status Tracking: Monitoring and storage of the return code from the most recent command (last_status), adhering to POSIX standards.
• Core Builtins: Native implementation of essential commands including cd, exit, echo, and type.
• Path Resolution: Integration with system environment variables to locate and launch external binaries.
• Error Handling: Systematic reporting of execution failures, including standard exit codes (e.g., 127 for command not found).

Demonstration

2026-03-01.13-12-54.mp4

Prerequisites

• GCC or Clang compiler
• CMake (version 3.10 or higher)

Compilation

This project utilizes CMake for build management. To compile the shell, execute the following commands from the project root:

mkdir build
cd build
cmake ..
make

Usage

Once compiled, the executable can be launched from the build directory: Bash

./msh

Technical Notes

• Signal Handling: Manages EOF (End Of File) for graceful session termination.

• Memory Management: Implements strict memory cleanup after each parsing cycle to prevent leaks during long-running sessions.

• Process Control: Uses fork, exec, and waitpid logic to manage external process lifecycles and accurately capture exit statuses via system macros.

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Why I did this

I wanted to experience some real system programming, I saw this excercise online and I decided to make it from scratc in C. And also because I dont know what I am doing with my life. lol.