Components

Components of a GNU Linux Operating System

Bootloader

• bootloader is the software which loads your os into the main memory
• grub and refind are examples of some popular bootloaders

Kernel

• main core of the operating system

init system

• how the processes are started on startup, etc controls that
• systemd
• init

shell

• where you enter commands it is the shell, different shells have different features
  • bash
  • zsh
  • fish
  • csh

Display Server

• so to run graphical interface on linux, you will need some software which will display those components and windows
• x and wayland are the popular choice of these
• x is old but has more software support
• wayland is new and better but not all types of software is available for it.

Display Manger

• when you login the login screen is the display manager, it manages sessions
• different de have different display managers, you can change them
• lightdm, sddm, gdm are some common display managers

Desktop Environment

• so desktop environment is how your interface looks and its default programs.
• desktop environment controls these things
  • default applications
  • your application launcher
  • notifications
  • keyboard shortcuts
  • how windows are displayed
  • icons and themes
• gnome, kde, xfce, lxde, mate some common desktop environment
• there are so many of them because everyone have their own preferences so use the one that works for you

Window managers

• when you install a desktop environment, it installs which power users don't need
• like a text editor, a terminal, calculator, music player, etc
• so to have more control you can just install window manager
• i3, bspwm, awesome, openbox, dwm, xmonad are common wm

Widget toolkit

• ui toolkit used to make an application
  • gtk and qt are the popular one used
  • kde use qt, gnome use gtk, two major desktop environment
• https://en.wikipedia.org/wiki/D-Bus - for process communication