• Binds to the basic structure of graphical-session-pre.target, graphical-session.target, xdg-desktop-autostart.target.
• Aadds custom nested slices app-graphical.slice, background-graphical.slice, session-graphical.slice to put apps in and terminate them cleanly on exit.
• Provides convenient way of launching apps to those slices.

• Templated units with specifiers.
• Named from common to specific where possible.
• Allowing for high-level name-.d drop-ins.

Currently included:

• sway
• wayfire
• labwc
• hyprland

• On startup environment is prepared by:
  • sourcing shell profile
  • sourcing uwsm-env, uwsm-env-${desktop} files from each dir of reversed ${XDG_CONFIG_HOME}:${XDG_CONFIG_DIRS} (in increasing priority), where ${desktop} is each item of ${XDG_CURRENT_DESKTOP}, lowercased
• Difference between environment state before and after preparation is exported into systemd user manager and dbus activation environment
• On shutdown previously exported variables are unset from systemd user manager (dbus activation environment does not support unsetting, so those vars are emptied instead (!))
• Lists of variables for export and cleanup are determined algorithmically by:
  • comparing environment before and after preparation procedures
  • boolean operations with predefined lists

• Actively select and launch compositor from Desktop entry (which is used as compositor instance ID):
  • Data taken from entry (Can be amended or overridden via cli arguments):
    • Exec for argument list
    • DesktopNames for XDG_CURRENT_DESKTOP and XDG_SESSION_DESKTOP
    • Name and Comment for unit Description
  • Entries can be overridden, masked or added in ${XDG_DATA_HOME}/wayland-sessions/
  • Optional interactive selector (requires whiptail), choice is saved in ${XDG_CONFIG_HOME}/uwsm-default-id
  • Desktop entry actions are supported
• Be launched via a Desktop entry by a login/display manager.

• XDG autostart services (app-*@autostart.service units) are placed into app-graphical.slice that receives stop action before compositor is stopped.
• Can be mass-controlled via stopping and starting wayland-session-xdg-autostart@${compositor}.target

All managed transient files (in /run/user/${UID}/systemd/user):

background-graphical.slice
app-graphical.slice
session-graphical.slice
[email protected]/slice-tweak.conf
[email protected]
wayland-session-shutdown.target
[email protected]
[email protected]
wayland-wm-app-daemon.service
[email protected]
wayland-wm-env@${compositor}.service.d/50_custom.conf
[email protected]
wayland-wm@${compositor}.service.d/50_custom.conf

See Longer story section below for descriptions.

• uwsm finalize: for finalizing service startup (compositor service unit uses Type=notify) and exporting variables set by compositor
• uwsm check may-start: for checking conditions for launch at login (for integration into login shell profile)
• uwsm app: for launching applications as scopes or services in proper slices
  • desktop entries or plain executables are supported
  • support for launching a terminal/in terminal (proposed xdg-terminal-exec)
  • flexible unit metadata support
• uwsm-app: a simple and fast shell client to app-daemon feature of uwsm, a drop-in replacement of uwsm app. The daemon (started on-demand) handles finding requested desktop entries, parsing and generation of commands for client to execute. This avoids the overhead of repeated python startup and increases app launch speed.
• uuctl: a graphical tool for managing user units (uses dmenu-like menus).

meson setup --prefix=/usr/local build
meson install -C build

Optional tools available in this project (see helpers and tools spoiler in concepts section above) can be enabled by adding arguments to meson setup:

• uuctl: -Duuctl=enabled.
• uwsm-app: -Duwsm-app=enabled.

https://aur.archlinux.org/packages/uwsm

https://github.com/minego/uwsm.nix

• It fills systemd and dbus environments with essential vars set by compositor: WAYLAND_DISPLAY, DISPLAY
• Any other vars can be given as arguments by name.
• Any exported variables are also added to cleanup list.
• If environment export is successful, it signals compositor service readiness, so graphical-session.target can properly be declared reached. If this stage fails, the compositor will be terminated in 10 seconds.

By default uwsm launhces compositor service in app.slice and all processes spawned by compositor will be a part of wayland-wm@${compositor}.service unit. This works, but is not an optimal solution.

Systemd documentation recommends running compositors in session.slice and launch apps as scopes or services in app.slice.

uwsm provides convenient way of handling this, It generates special nested slices that will also receive stop action ordered before wayland-wm@${compositor}.service shutdown:

• app-graphical.slice
• background-graphical.slice
• session-graphical.slice

app-*@autostart.service units are also modified to be started in app-graphical.slice.

To launch an app inside one of those slices, use:

uwsm app [-s a|b|s|custom.slice] [-t scope|service] -- your_app [with args]

Launching desktop entries via a valid ID is also supported, (optionally with an action ID appended via ':'):

uwsm app [-s a|b|s|custom.slice] [-t scope|service] -- your_app.desktop[:action] [with args]

In this case args must be supported by the entry or its selected action according to XDG Desktop Entry Specification.

Specifying paths to executables or desktop entry files is also supported.

Always use -- to disambiguate command line if any dashed arguments are intended for the app being launched.

Example snippets for sway config for launching apps:

Launch proposed default terminal:

bindsym --to-code $mod+t exec exec uwsm app -T

Fuzzel has a very handy launch-prefix option:

bindsym --to-code $mod+r exec exec fuzzel --launch-prefix='uwsm app --' --log-no-syslog --log-level=warning

Launch SpaceFM via a desktop entry:

bindsym --to-code $mod+e exec exec uwsm app spacefm.desktop

Featherpad desktop entry has "standalone-window" action:

bindsym --to-code $mod+n exec exec uwsm app featherpad.desktop:standalone-window

Unit type of launched apps can be controlled by -t service|scope argument or setting its default via UWSM_APP_UNIT_TYPE env var.

uwsm start [-[a|e]D DesktopName1[:DesktopMame2:...]] [-N Name] [-C "Compositor description"] -- ${compositor} [with "any complex" --arguments]

If ${compositor} is a desktop entry ID, uwsm will get desktop entry from wayland-sessions data hierarchy, Exec will be used for command line, and DesktopNames will fill $XDG_CURRENT_DESKTOP, Name and Comment will go to units' descriptons.

Arguments provided on command line are appended to the command line of session desktop entry (unlike application entries), no argument processing is done (Please file a bug report if you encounter any wayland-sessions desktop entry with %-fields which would require this behavior to be altered).

If you want to customize compositor execution provided with a desktop entry, copy it to ~/.local/share/wayland-sessions/ and change to your liking, including adding actions.

If ${compositor} is select or default, uwsm invokes a menu to select desktop entries available in wayland-sessions data hierarchy (including their actions). Selection is saved, previous selection is highlighted (or launched right away in case of default). Selected entry is used as instance ID.

There is also a separate select action (uwsm select) that only selects and saves default ${compositor} and does nothing else, which is handy for seamless shell profile integration.

(At least for now) units are generated by the script.

Run uwsm start -o ${compositor} to populate ${XDG_RUNTIME_DIR}/systemd/user/ with them and do nothing else (-o).

Any remainder arguments are appended to compositor argument list (even when ${compositor} is a desktop entry). Use -- to disambigue:

uwsm start -o -- ${compositor} with "any complex" --arguments

Desktop entries can be overridden or added in ${XDG_DATA_HOME}/wayland-sessions/.

Basic set of generated units:

• templated targets boud to stock systemd user-level targets
  • [email protected]
  • [email protected]
  • [email protected]
• templated services
  • [email protected] - environment preloader service
  • [email protected] - main compositor service
  • wayland-wm-app-daemon.service - fast app command generator
• slices for apps nested in stock systemd user-level slices
  • app-graphical.slice
  • background-graphical.slice
  • session-graphical.slice
• tweaks
  • wayland-wm-env@${compositor}.service.d/custom.conf, wayland-wm@${compositor}.service.d/custom.conf - if arguments and/or various names were given on command line, they go here.
  • [email protected]/slice-tweak.conf - assigns XDG autostart apps to app-graphical.slice
• shutdown and cleanup target
  • wayland-session-shutdown.target - conflicts with operational units. Triggered by the end of wayland-wm*.service units for more robust cleanup, including on failures. But can also be called manually for shutdown.

After units are generated, compositor can be started by: systemctl --user start wayland-wm@${compositor}.service

Add --wait to hold terminal until session ends.

exec it from login shell to bind to login session:

exec systemctl --user start --wait wayland-wm@${compositor}.service

Still if login session is terminated, wayland session will continue running, most likely no longer being accessible.

To also bind it the other way around, shell traps are used:

trap "if systemctl --user is-active -q wayland-wm@${compositor}.service ; then systemctl --user --stop wayland-wm@${compositor}.service ; fi" INT EXIT HUP TERM

This makes the end of login shell also be the end of wayland session.

When [email protected] is started during graphical-session-pre.target startup, uwsm aux prepare-env ${compositor} is launched (with shared set of custom arguments).

It runs shell code to prepare environment, that sources shell profile, uwsm-env* files, anything that plugins dictate. Environment state at the end of shell code is given back to the main process. uwsm is also smart enough to find login session associated with current TTY and set $XDG_SESSION_ID, $XDG_VTNR.

The difference between initial env (that is the state of activation environment) and after all the sourcing and setting is done, plus varnames.always_export, minus varnames.never_export, is added to activation environment of systemd user manager and dbus.

Those variable names, plus varnames.always_cleanup minus varnames.never_cleanup are written to a cleanup list file in runtime dir.

[email protected] uses Type=notify and waits for compositor to signal started state. Activation environments will also need to receive essential variables like WAYLAND_DISPLAY to launch graphical applications successfully.

uwsm finalize [VAR [VAR2...]] runs:

dbus-update-activation-environment --systemd WAYLAND_DISPLAY DISPLAY [VAR [VAR2...]]
systemctl --user import-environment WAYLAND_DISPLAY DISPLAY [VAR [VAR2...]]
systemd-notify --ready

The first two together might be an overkill.

Only defined variables are used. Variables that are not blacklisted by varnames.never_cleanup set are also added to cleanup list in runtime dir.

Just stop the main service: systemctl --user stop "wayland-wm@${compositor}.service", everything else will stopped by systemd.

Wildcard systemctl --user stop "wayland-wm@*.service" will also work.

If start command was run with exec from login shell or .profile, this stop command also doubles as a logout command.

When wayland-wm-env@${compositor}.service is stopped, uwsm aux cleanup-env is launched. It looks for any cleanup files (env_names_for_cleanup_*) in runtime dir. Listed variables, plus varnames.always_cleanup minus varnames.never_cleanup are emptied in dbus activation environment and unset from systemd user manager environment.

When no compositor is running, units can be removed (-r) by uwsm stop -r.

Add compositor to -r to remove only customization drop-ins: uwsm stop -r ${compositor}.

This example does the same thing as check may-start + start subcommand combination described earlier: starts wayland session automatically upon login on tty1 if system is in graphical.target

Screening for being in interactive login shell here is essential ([ "${0}" != "${0#-}" ]). wayland-wm-env@${compositor}.service sources profile, which has a potential for nasty loops if run unconditionally. Other conditions are a recommendation:

MY_COMPOSITOR=sway
if [ "${0}" != "${0#-}" ] &&
   [ "$XDG_VTNR" = "1" ] &&
   systemctl is-active -q graphical.target &&
   ! systemctl --user is-active -q wayland-wm@*.service
then
    uwsm start -o ${MY_COMPOSITOR}
    trap "if systemctl --user is-active -q wayland-wm@${MY_COMPOSITOR}.service ; then systemctl --user --stop wayland-wm@${MY_COMPOSITOR}.service ; fi" INT EXIT HUP TERM
    echo Starting ${MY_COMPOSITOR} compositor
    systemctl --user start --wait wayland-wm@${MY_COMPOSITOR}.service &
    wait
    exit
fi