MicroShell

A Simple Shell Implementation in C++

   The Microshell is a lightweight, command-line shell program implemented in C++. It offers basic shell functionality, including executing commands, piping, and error handling. This microshell serves as an educational project and provides insights into working with processes, pipes, and command execution in a Unix-like environment.

Features

The Microshell showcases key computing concepts for software programming:

• Forking process to create child processes.
• Executing external programs using 'execv' and 'execvp'.
• Building an interactive command-line interface.
• Implementing error handling.

Concepts Explored

The Microshell provides hands-on experience with several important computing concepts often sought after in employment:

Process Management

• Parallel Programming through Forking Processes:  The Microshell demonstrates how to fork processes, creating child processes that execute commands. This concept is fundamental for concurrent and parallel programming.

Executing External Programs

The Microshell program showcases the use of 'execv()' and 'execvp()' to execute external programs from within a C++ program. This is a crucial skill for developing software that interacts with various system utilities and tools.

• 'execv()':  This method requires the program name and the full path to the executable program.
• 'execvp()':  This method requires the program name and will search for the executable in the 'PATH' variable.

Command-Line Interface

• Interactive Command Line: The Microshell offers an interactive command-line interface, where users can enter commands and see their results. Understanding how to build a command-line interface is valuable for creating user-friendly applications

Error Handling

• Basic Error Handling: The Microshell incorporates essential error handling mechanisms to verify the existence and accessibility of an executable file. Proficiency in gracefully managing errors is a fundamental skill in software development, ensuring robust and reliable program execution.

Getting Started

The program relies on a Unix-based operating system to support the forking and execution calls, specifically 'execv' and 'execvp'.

Prerequisites

Before you can execute this program, make sure you have the following:

• GNU Make 4.2.1 or newer: required to execute the Make instructions to build the program executables.
• g++ Compiler: The GNU compiler is used to build and run the program. the compiler must support C++11.

Usage

• Clone this repo to your local machine.

This project is built and operated through the command line interface.

To begin the program:

• Open a terminal window and navigate to the folder that contains the project files.

• Run the following command to build the program: make ./msh

• Run the following to run the program ./msh

To use the program:

  After the program prompts the user with a simulated username of "cssc1401%", The user can proceed to enter shell commands.

• Some Example Commands:
  • ls -la
  • ls -la | sort -fi
  • ls -la | sort -fi | grep bash.src

Note:   More than three commands piped together and commands with more than one optional argument are not allowed.

To exit the program:

• enter exit.