Distinguish between Desktop session and desktop environment

desktop-environmentgdmsessionwindow-manager

I heard/observed following words and want to distinguish information.

  • Desktop Environment
  • Desktop Session
  • GDM Session
  • Shell
  • Window Manager

So I can understand exact difference and working relation between them.

Best Answer

  • A desktop environment (DE) is a combination of programs that define the interaction of the user and his applications.
    • Examples: Ubuntu's Unity, GNOME, KDE
  • A desktop session is a running instance of a desktop environment.
  • A GDM session is a session of the X display manager GDM (Gnome Display Manager), which mainly allows you to choose a desktop environment to run a desktop session.
    • Xdm is the X display manager that is part of the X distribution. Gdm and lightdm are newer variants.
    • An X display manager presents the graphical login screen, an can support to log in locally, or to remote hosts.
  • The term "shell" is very generic, and mostly referring to interactive command line programs like bash - but I'm not sure that's what was meant in the question.
  • A window manager is a program that handles location, size, visibility and other aspects of the windows used in a desktop session, so it is an important component of a desktop environment.
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