Where Is the GDM Config File?
GDM customizes through /etc/gdm/custom.conf, with dconf databases handling the greeter theme.
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GDM reads local login policy from /etc/gdm/custom.conf. Automatic login, timed login, and Wayland toggles live under the daemon section there. Everything else ships as compiled defaults that this file overrides.
Greeter appearance works differently. Themes and logos come from dconf databases for the gdm user, not from custom.conf. Edits to custom.conf apply on the next login screen without touching user sessions.
Where GDM stores this, by platform
/etc/gdm/custom.conf
Daemon section holds autologin and Wayland settings. Survives package upgrades unlike files under /usr/share. Restart gdm to apply login changes.
Frequently asked questions
How do I enable automatic login in GDM?
Set AutomaticLoginEnable and AutomaticLogin in the daemon section of custom.conf. The user must exist with a valid shell. Timed login uses the TimedLogin keys instead.
Why did my GDM theme change disappear?
Greeter theming lives in the gdm user dconf database, which custom.conf never touches. Theme edits need the gdm profile path. Config file changes only affect login behavior.
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