erdemOS

Simple Linux userspace environment with a custom init system and shell (ersh) that boots with the host system's Linux kernel in QEMU.

Features

• Custom init system - Minimal init process with proper signal handling
• ersh (Erdem Shell) - Custom shell with built-in commands
• Colorized output - ANSI color support with erdemOS color scheme
• Power management - Integrated poweroff command
• Static binaries - Self-contained executables with no dependencies

Requirements

• gcc (with static linking support)
• qemu-system-x86_64
• Linux kernel (available at /boot/vmlinuz-*)
• cpio, gzip

On Debian/Ubuntu: sudo apt-get install build-essential qemu-system-x86 cpio gzip

Build and run

./build.sh   # Compiles init, ersh, and poweroff; creates initramfs
./run.sh     # Boots with host kernel in QEMU
./clean.sh   # Removes build artifacts

ersh - Erdem Shell

The custom shell includes the following built-in commands:

• cd <dir> - Change directory
• exit - Exit shell (returns to init)
• help [command] - Show built-in commands or detailed help for a specific command
• kbd <layout> - Change keyboard layout (trq for Turkish Q, trf for Turkish F, en for English)
• license - Show license (displays copyright and Apache License 2.0 information)
• ls [-al] [dir] - List directory contents (supports -a for all files, -l for long format)
• mkdir <dir> - Create directory
• poweroff - Exit shell and power off the system
• pwd - Print working directory
• rm [-rf] <file/dir> - Remove file or directory (supports -r/-R for recursive, -f for force)
• touch <file> - Create empty file
• ver - Show version (displays "erdemOS" and version number)

External commands can also be executed if available in the initramfs.

How it works

• Compiles static binaries for init, ersh shell, poweroff utility, and loadkeys utility
• Creates a minimal initramfs containing all binaries in /bin/
• Boots QEMU with the host's Linux kernel and the custom initramfs
• The kernel executes /bin/init which launches /bin/ersh
• The shell provides an interactive command-line interface
• Uses ANSI escape codes for colorized terminal output
• Custom loadkeys utility supports Turkish Q, Turkish F, and English layouts

Files

• src/init.c - Init process with signal handling and shell launching
• src/ersh.c - Custom shell with built-in commands
• src/poweroff.c - Power off utility using Linux reboot syscall
• src/loadkeys.c - Keyboard layout loader utility
• include/colors.h - ANSI color definitions for erdemOS
• include/version.h - Version definitions generated from VERSION file
• VERSION - Project version number (currently 0.0.3)
• build.sh - Compiles all programs and creates initramfs
• run.sh - Launches QEMU with the host kernel
• clean.sh - Removes build artifacts

Color Scheme

erdemOS uses ANSI escape codes with the following color scheme:

• Cyan - Primary color for normal text and titles
• Magenta - Shell prompt
• Green - Command names
• Blue - Informational headers
• Yellow - Warnings
• Red - Errors

Copyright and License

Copyright (c) 2025 Erdem Ersoy (eersoy93)

Licensed with Apache License 2.0

Used with GitHub Copilot.