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Eshell

Eshell is the interactive shell interface for the Echo Kernel. It provides a command-line interface for interacting with the system.

Features​

  • Command-line interface with colored prompt
  • Command history support
  • Error handling for unknown commands
  • Built-in system commands

Command Prompt​

The Eshell prompt consists of two parts:

  • Username and system identifier (user@system:$) in red
  • Command marker (>) in light blue

Available Commands​

clear​

Clears the screen, removing all previous output.

Usage:

clear

shutdown​

Safely shuts down the system using multiple methods:

  1. ACPI shutdown (QEMU)
  2. APM shutdown (Bochs, older QEMU)
  3. Keyboard controller reset
  4. CPU halt (fallback)

Usage:

shutdown

help​

Displays a list of available commands with their descriptions.

Usage:

help

Implementation Details​

Color Scheme​

  • Prompt: Red (CL_RED)
  • Command marker: Light Blue (CL_LIGHT_BLUE)
  • Help text: Light Blue (CL_LIGHT_BLUE)
  • Error messages: Light Blue (CL_LIGHT_BLUE)
  • User input: Light Grey (CL_LIGHT_GREY)
  • Welcome message: Light Green (CL_LIGHT_GREEN)
  • Shutdown message: Light Red (CL_LIGHT_RED)

Source Files​

  • Main implementation: src/kernel/kernel.cpp
  • Display functions: src/sys/display.h
  • Keyboard input: src/sys/keyboard.h
  • Port I/O: src/sys/ports.h

Architecture​

The shell is implemented in the kernel::eshell namespace and consists of two main functions:

  • start_eshell(): Initializes the shell and displays the welcome message
  • loop(): Handles the command input and execution loop

Future Enhancements​

Planned features for future versions:

  • Command history navigation
  • Tab completion
  • File system commands
  • Process management commands
  • System information commands