Provided by: gnome-session-bin_42.0-1ubuntu2_amd64 
NAME
gnome-session - Start the GNOME desktop environment
SYNOPSIS
gnome-session [-a|--autostart=DIR] [--session=SESSION] [--failsafe|-f] [--debug] [--whale]
DESCRIPTION
The gnome-session program starts up the GNOME desktop environment. This command is
typically executed by your login manager (either gdm, xdm, or from your X startup
scripts). It will load either your saved session, or it will provide a default session for
the user as defined by the system administrator (or the default GNOME installation on your
system). Note that gnome-session is a wrapper script for gnome-session-binary.
The default session is defined in gnome.session, a .desktop-like file that is looked for
in $XDG_CONFIG_HOME/gnome-session/sessions, $XDG_CONFIG_DIRS/gnome-session/sessions and
$XDG_DATA_DIRS/gnome-session/sessions.
When saving a session, gnome-session saves the currently running applications in the
$XDG_CONFIG_HOME/gnome-session/saved-session directory. Saving sessions is only supported
with the legacy non-systemd startup method.
gnome-session is an X11R6 session manager. It can manage GNOME applications as well as any
X11R6 SM compliant application.
OPTIONS
The following options are supported:
--autostart=DIR
The directory DIR to be searched for autostart .desktop files. This option can be
used multiple times. When this option is present, then default autostart
directories will not be searched.
--session=SESSION
Use the applications defined in SESSION.session. If not specified, gnome.session
will be used.
--builtin
Use the legacy non-systemd method of managing the user session. This is the
opposite of the --systemd option.
--systemd
Use the systemd method of managing the user session. This is the opposite of the
--builtin option.
--failsafe
Run in fail-safe mode. User-specified applications will not be started.
--debug
Enable debugging code.
--whale
Show the fail whale in a dialog for debugging it.
SESSION DEFINITION
Sessions are defined in .session files, that are using a .desktop-like format, with the
following keys in the GNOME Session group:
Name Name of the session. This can be localized.
RequiredComponents
List of component identifiers (desktop files) that are required by the session. The
required components will always run in the session.
Here is an example of a session definition:
[GNOME Session]
Name=GNOME
RequiredComponents=gnome-shell;gnome-settings-daemon;
In systemd managed sessions the RequiredComponents may be provided by systemd units
instead. In this case the corresponding .desktop file needs to contain X-GNOME-
HiddenUnderSystemd=true. gnome-session will ignore these components and rely on systemd to
manage them appropriately, see the systemd for more information on how this works.
The .session files are looked for in $XDG_CONFIG_HOME/gnome-session/sessions,
$XDG_CONFIG_DIRS/gnome-session/sessions and $XDG_DATA_DIRS/gnome-session/sessions.
systemd
gnome-session can pass much of the session management over to systemd (see the --systemd
option which may be the default since 3.34). In this case, startup components that have X-
GNOME-HiddenUnderSystemd=true set in their .desktop file will be ignored by gnome-session.
It instead relies on the fact that these components are managed by systemd.
As of GNOME 3.34 the systemd support is new and the customizing the configuration is not
yet easily possible. With GNOME 3.34 it may be best to use --builtin if session
customizations are required. This is due to the way that GNOME currently defines the
components that will be started on each session type.
systemd provides the two special targets graphical-session.target and graphical-session-
pre.target which are fully functional and should be used. gnome-session provides the
following main targets:
gnome-session.target
Generic unit that will be active throughout the session. Similar to graphical-
session.target.
gnome-session-pre.target
Used for tasks that need to be done before session startup. Similar to graphical-
session-pre.target.
gnome-session-x11@SESSION.target gnome-session-wayland@SESSION.target
Main unit started for X11/wayland based session. SESSION is set according to the
session that is passed in --session.
gnome-session-x11.target gnome-session-wayland.target
Convenience units without the session embedded into the target.
gnome-session@SESSION.target
Convenience unit with just the SESSION information embedded.
gnome-session-x11-services.target
Special unit started when X11 services are needed. This will be used from GNOME
3.36 onwards. Programs will need to use the special GNOME_SETUP_DISPLAY environment
variable instead of DISPLAY.
Note that care must be taken to set appropriate After= rules. It is also strongly
recommended to always do this in combination with BindsTo= or PartOf= on one of the core
targets (e.g. graphical-session.target).
Units are required to set CollectMode=inactive-or-failed. In addition, it is strongly
recommended to set TimeoutStopSec=5 so that logout will not be delayed indefinitely in
case the process does not stop properly.
ENVIRONMENT
gnome-session sets several environment variables for the use of its child processes:
SESSION_MANAGER
This variable is used by session-manager aware clients to contact gnome-session.
DISPLAY
This variable is set to the X display being used by gnome-session. Note that if the
--display option is used this might be different from the setting of the
environment variable when gnome-session is invoked.
Behavior of gnome-session ifself can be modified via the following environment variable:
GNOME_SESSION_AUTOSTART_DIR
This variable specifies a list of directories to the searched for autostart files.
This variable overrides all directories specified via the --autostart option, as
well as all default autostart directories.
FILES
$XDG_CONFIG_HOME/autostart $XDG_CONFIG_DIRS/autostart /usr/share/gnome/autostart
Applications defined via .desktop files in those directories will be started on
login. gnome-session-properties(1) can be used to easily configure them.
$XDG_CONFIG_HOME/gnome-session/sessions $XDG_CONFIG_DIRS/gnome-session/sessions
$XDG_DATA_DIRS/gnome-session/sessions
These directories contain the .session files that can be used with the --session
option.
$XDG_CONFIG_HOME/gnome-session/saved-session
This directory contains the list of applications of the saved session.
BUGS
If you find bugs in the gnome-session program, please report these on
https://gitlab.gnome.org/GNOME/gnome-session/issues.
SEE ALSO
gnome-session-properties(1) gnome-session-quit(1)