Simple Shell Implementation

This repository contains the implementation of a basic shell in C, created as part of a lab exercise to deepen understanding of process management in Linux.

Features

Part A: Simple Shell

• Execute Basic Linux Commands: The shell accepts user input, forks a child process, executes the command using the exec system call, and reaps the child using the wait system call.
• Prompt: The shell uses $ as the command prompt and continues to run until terminated by Ctrl+C.
• Error Handling: Handles errors gracefully, including empty commands and invalid input. Does not crash and displays an appropriate error message.
• Change Directory (cd): Supports cd to change the current working directory.

Part B: Background Execution

• Background Processes: Supports background execution of processes using the & operator. Background processes do not block the shell from accepting new commands.
• Child Reaping: Reaps background processes periodically when receiving new input.

Part C: Exit Command

• exit Command: Allows the shell to exit gracefully by terminating all background processes and cleaning up resources.

Part D: Ctrl+C Handling

• Signal Handling: The shell catches the Ctrl+C signal (SIGINT) and ensures that only the foreground process is terminated. The shell itself continues running.

Part E: Serial and Parallel Execution

• Serial Execution: Commands separated by && are executed sequentially.
• Parallel Execution: Commands separated by &&& are executed in parallel.

Getting Started

Prerequisites

• Linux Environment: The shell is developed and tested in a Linux environment.
• GCC Compiler: Ensure that GCC is installed to compile the shell.

Compilation

To compile the shell, run:

gcc myshell.c -o myshell

Running the Shell

To run the shell, use:

./myshell

Once running, the shell will display the $ prompt, where you can enter commands.

Supported Commands

• Basic Linux commands like ls, cat, echo, and sleep.
• cd command to change directories.
• Background execution using &.
• Serial execution using &&.
• Parallel execution using &&&.
• exit command to terminate the shell.

Example Usage

$ ls
file1.txt  file2.txt
$ sleep 10 &
$ cd ..
$ exit