shell

shell.py

#!/usr/bin/env python3
"""
A basic shell with TUI using only Python standard libraries.
Works cross-platform (Windows, Linux, macOS).
"""

import os
import sys
import subprocess

# ANSI escape codes for colors and formatting
class ANSI:
    # Formatting
    RESET = '\033[0m'
    BOLD = '\033[1m'
    
    # Colors
    GREEN = '\033[32m'
    BLUE = '\033[34m'
    RED = '\033[31m'
    
    # Cursor and screen
    CLEAR_SCREEN = '\033[2J'
    CURSOR_HOME = '\033[H'

def enable_windows_ansi():
    """Enable ANSI escape sequences on Windows"""
    if sys.platform == "win32":
        try:
            import ctypes
            kernel32 = ctypes.windll.kernel32
            kernel32.SetConsoleMode(kernel32.GetStdHandle(-11), 7)
        except:
            pass

def get_prompt():
    """Generate a simple cross-platform prompt"""
    try:
        cwd = os.getcwd()
        # Shorten home directory path
        home = os.path.expanduser("~")
        if cwd.startswith(home):
            cwd = "~" + cwd[len(home):]
    except:
        cwd = "."
    
    return f"{ANSI.GREEN}> {ANSI.RESET}"

def execute_command(command):
    """Execute a command and return its output"""
    command = command.strip()
    if not command:
        return ""
    
    # Built-in commands
    if command == "exit":
        return None  # Special signal to exit
    elif command == "clear":
        # Return special clear screen sequence
        return ANSI.CLEAR_SCREEN + ANSI.CURSOR_HOME
    elif command.startswith("cd "):
        try:
            path = command[3:].strip()
            os.chdir(os.path.expanduser(path))
            return ""
        except Exception as e:
            return f"cd: {e}"
    
    # External commands
    try:
        result = subprocess.run(
            command,
            shell=True,
            capture_output=True,
            text=True,
            timeout=10
        )
        output = result.stdout
        if result.stderr:
            output += result.stderr
        return output
    except subprocess.TimeoutExpired:
        return "Command timed out"
    except Exception as e:
        return f"Error: {e}"

def main():
    """Main shell loop"""
    # Enable ANSI support on Windows
    enable_windows_ansi()
    
    # Clear screen
    sys.stdout.write(ANSI.CLEAR_SCREEN + ANSI.CURSOR_HOME)
    sys.stdout.flush()
    
    print("Simple Shell - Type 'exit' to quit")
    
    while True:
        try:
            # Show prompt
            prompt = get_prompt()
            command = input(prompt)
            
            # Execute command
            result = execute_command(command)
            
            # Handle special cases
            if result is None:  # Exit command
                break
            elif result == ANSI.CLEAR_SCREEN + ANSI.CURSOR_HOME:  # Clear command
                sys.stdout.write(result)
                sys.stdout.flush()
            elif result:
                print(result, end='')
                
        except KeyboardInterrupt:
            print()  # New line after Ctrl+C
            continue
        except EOFError:
            print()  # New line on Ctrl+D
            break
        except Exception as e:
            print(f"Shell error: {e}")
    
    print(f"{ANSI.RESET}Goodbye!")

if __name__ == "__main__":
    main()