GNOME Display Manager

lastmod 2026-05-18created 2026-05-181 edits

GNOME Display Manager (GDM) is a graphical login manager ("display manager") for the windowing systems X11 and Wayland.

The X Window System by default uses the XDM display manager. However, resolving XDM configuration issues typically involves editing a configuration file. GDM allows users to customize or troubleshoot settings without having to resort to a command line. Users can pick their session type on a per-login basis. GDM 2.38.0 is the last version that features customization with themes; subsequent releases do not support themes.

Disabling suspend on an Ubuntu laptop

Arch Wiki — Power management
GNOME — dconf system defaults
Auto boot on power restore settings — BIOS AC Power Recovery setting
systemd — logind and target management

Describes how to configure an Ubuntu laptop so that it does not automatically suspend, not only in the session after login but also on the post-logout waiting screen (GDM greeter).

Background

The post-logout waiting screen runs as a separate GNOME session. That is, gnome-settings-daemon (gsd-power), run by the gdm user, manages idle suspend with its own dconf settings, so the /etc/systemd/logind.conf settings alone cannot prevent idle suspend on the greeter screen.

Lid (closing the lid) / power button — handled at the logind level, so logind settings also apply to the greeter
Idle timeout suspend — GNOME (gsd-power) overrides the logind settings, so separate configuration is needed

Method 1: Modify the GDM greeter dconf defaults (recommended)

Add the power management keys to the greeter-only dconf defaults file.

sudo nano /etc/gdm3/greeter.dconf-defaults

Add the block below, or merge it into the existing [org/gnome/settings-daemon/plugins/power] section.

[org/gnome/settings-daemon/plugins/power]
# Disable idle suspend on AC / 충전 중 idle 절전 비활성화
sleep-inactive-ac-type='nothing'
# Disable idle suspend on battery / 배터리 idle 절전 비활성화
sleep-inactive-battery-type='nothing'

After applying, restart GDM. Because this ends the active GUI session, running it from a TTY or SSH is recommended.

sudo systemctl restart gdm3

If the change is not reflected, recompile the greeter dconf DB.

sudo dpkg-reconfigure gdm3   # greeter dconf db 재생성 / rebuild greeter dconf db

Check logind.conf (lid / power button)

This is also covered in Systemd#How to apply the same behavior in the logged-out state.

Lid-close and power button behavior is at the logind level, so it applies to the greeter as is. If you have not configured it yet, check it as well.

# /etc/systemd/logind.conf
HandleLidSwitch=ignore
HandleLidSwitchExternalPower=ignore
HandleLidSwitchDocked=ignore
IdleAction=ignore

Apply after changing (beware: the GUI session will be disconnected):

sudo systemctl restart systemd-logind

Method 2: Mask the suspend targets (global, definitive)

Completely blocks suspend system-wide, regardless of session or greeter.

sudo systemctl mask sleep.target suspend.target hibernate.target hybrid-sleep.target

This is the most definitive, but the user can no longer suspend manually on purpose either. To revert, use unmask.

sudo systemctl unmask sleep.target suspend.target hibernate.target hybrid-sleep.target

Comparison of methods

Item	Method 1 (greeter dconf)	Method 2 (target mask)
Scope	Greeter idle suspend only	System-wide suspend
Manual suspend	Possible	Not possible
Recommended when	You sometimes close the laptop to put it to sleep	You never use suspend, like a desktop
Reverting	Remove the dconf keys and restart	`systemctl unmask`

Verification

After logging out, leave the greeter screen idle for longer than the configured idle timeout and confirm that it does not go into suspend. Most cases of the "suspends after a while on the login screen" symptom are solved by Method 1.

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Category:Ubuntu Category:Linux Category:Power management

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