Cell Shell Documentation

Table of Contents

• Overview
• Files
• Key Components
• Usage
• Current Limitations
• Future Enhancements

GITHUB

• REPO - https://github.com/Shubham-py404/CPP-SHELL.git

init repo - 
echo "# CPP-SHELL" >> README.md
git init
git add README.md
git commit -m "first commit"
git branch -M main
git remote add origin https://github.com/Shubham-py404/CPP-SHELL.git
git push -u origin main

g++ cell.cpp utils.cpp builtin.cpp -o cell && ./cell

Overview

Cell is a simple command-line shell implementation written in C++. It provides a basic Read-Eval-Print Loop (REPL) that reads user input, processes it, and displays output with color formatting.

Files

• cell.hpp: Header file containing includes, color definitions, and utility macros
• cell.cpp: Main implementation file with the shell logic
• utils.cpp
• builtin.cpp

Key Components

Header File (cell.hpp)

Includes

• <iostream>: For input/output operations
• <unistd.h>: Provides fork() and execvp() functions for process management (Linux systems)
• <sys/wait.h>: Contains wait() function for process synchronization
• <cstdlib>: Defines EXIT_SUCCESS constant
• <vector>: For dynamic arrays (included but not used in current implementation)
• <string>: For string operations (included but not used in current implementation)

Color Definitions

ANSI escape codes for terminal text coloring:

• YELLOW: Yellow text color
• RED: Red text color
• CYAN: Cyan text color
• GREEN: Green text color
• RST: Reset to default color

Implementation File (cell.cpp)

cell_read_line() Function

Purpose: Reads a single line of input from the user via stdin.

Parameters: None

Behavior:

1. Displays a green prompt "$$> " to indicate readiness for input
2. Uses getline() to read input from stdin
3. Handles EOF condition (Ctrl+D) by printing "[EOF]" in red
4. Handles getline errors by printing "Getline failed" in red
5. Echoes the entered text in yellow for confirmation
6. Returns the buffer containing the input

main() Function

Purpose: Implements the main REPL loop of the shell.

Behavior:

1. Enters an infinite loop
2. Calls cell_read_line() to get user input
3. If input is NULL (EOF/error), breaks out of loop
4. Prints the input line
5. Frees the memory allocated by getline()
6. Continues loop for next input

Future Enhancements

• Command parsing and execution
• Built-in commands (cd, exit, etc.)
• Command history
• Tab completion
• Cross-platform compatibility

CPP-SHELL