Wayland
Wayland is a new display protocol that aims to replace X11.
Multiple compositor implementations exist, including Sway, Mutter (GNOME's compositor) and Kwin (KDE's compositor). A more exhaustive list is available in the ArchWiki.
XDG_RUNTIME_DIR
As per the protocol spec, Wayland compositors require the XDG_RUNTIME_DIR variable to be set. There are a few ways to configure create a temporary runtime directory and export this variable:
- elogind can do this and also export other XDG environment variables automatically for each session.
- pam-rundir can handle this for logins. To use this PAM is required.
- mkrundir is an executable that can be used to initialise the runtime directory explicitly by each user.
- Setting it up manually (see below).
Note that this variable MUST be initialised before the Wayland compositor, and also before the D-Bus session instance is started.
Configuring XDG_RUNTIME_DIR manually
Generally, care should be taken when configuring the XDG_* variables manually as this configuration may have errors or conflict with other utilities that do this automatically.
On a system that's not using elogind nor any pam module that handles this, the XDG_RUNTIME_DIR can be initialised manually. The easiest approach is by adding a snippet like this one to shell init scripts (e.g.: ~/.profile):
Contents of ~/.profile