GDM
Related articles
From GDM - GNOME Display Manager:
- The GNOME Display Manager (GDM) is a program that manages graphical display servers and handles graphical user logins.
Display managers provide X Window System users with a graphical login prompt.
Contents
- 1 Installation
-
2 Configuration
- 2.1 Log-in screen background image
- 2.2 Log-in screen logo
- 2.3 Changing the GDM cursor theme
- 2.4 Larger font for log-in screen
- 2.5 Turning off the sound
- 2.6 Make the power button interactive
- 2.7 Prevent suspend when closing the lid
- 2.8 GDM keyboard layout
- 2.9 Change the language
- 2.10 Automatic login
- 2.11 Passwordless login
- 2.12 Passwordless shutdown for multiple sessions
- 2.13 Add or edit GDM sessions
- 2.14 Enable root login in GDM
- 2.15 Hide user from login list
- 2.16 Rotate login screen
- 2.17 xrandr at login
- 2.18 Configure X server access permission
- 3 Troubleshooting
- 4 See also
Installation
GDM can be installed with the gdm package, and it is installed as part of the gnome group. To start GDM at boot time enable gdm.service
.
If you would prefer to use legacy GDM which was used in GNOME 2 and has its own configuration utility, install the gdm-oldAUR package. Note that the rest of this article discusses current GDM, not legacy GDM, unless indicated otherwise.
You might also wish to install the following:
- gdm3setup — An interface to configure GDM3, autologin options and change Shell theme
Configuration
Log-in screen background image
Firstly, you need to extract the existing GNOME Shell theme to a folder in your home directory. You can do this using the following script:
extractgst.sh
#!/bin/sh workdir=${HOME}/shell-theme if [ ! -d ${workdir}/theme ]; then mkdir -p ${workdir}/theme fi gst=/usr/share/gnome-shell/gnome-shell-theme.gresource for r in `gresource list $gst`; do gresource extract $gst $r >$workdir${r/#\/org\/gnome\/shell/} done
Navigate to the created directory. You should find that the theme files have been extracted to it. Now copy your preferred background image to this directory.
Next, you need to create a file in the directory with the following content:
gnome-shell-theme.gresource.xml
<?xml version="1.0" encoding="UTF-8"?> <gresources> <gresource prefix="/org/gnome/shell/theme"> <file>calendar-arrow-left.svg</file> <file>calendar-arrow-right.svg</file> <file>calendar-today.svg</file> <file>checkbox-focused.svg</file> <file>checkbox-off-focused.svg</file> <file>checkbox-off.svg</file> <file>checkbox.svg</file> <file>close-window.svg</file> <file>close.svg</file> <file>corner-ripple-ltr.png</file> <file>corner-ripple-rtl.png</file> <file>dash-placeholder.svg</file> <file>filter-selected-ltr.svg</file> <file>filter-selected-rtl.svg</file> <file>gnome-shell.css</file> <file>gnome-shell-high-contrast.css</file> <file>logged-in-indicator.svg</file> <file>filename</file> <file>more-results.svg</file> <file>no-events.svg</file> <file>no-notifications.svg</file> <file>noise-texture.png</file> <file>page-indicator-active.svg</file> <file>page-indicator-inactive.svg</file> <file>page-indicator-checked.svg</file> <file>page-indicator-hover.svg</file> <file>process-working.svg</file> <file>running-indicator.svg</file> <file>source-button-border.svg</file> <file>summary-counter.svg</file> <file>toggle-off-us.svg</file> <file>toggle-off-intl.svg</file> <file>toggle-on-us.svg</file> <file>toggle-on-intl.svg</file> <file>ws-switch-arrow-up.png</file> <file>ws-switch-arrow-down.png</file> </gresource> </gresources>
Replace filename with the filename of your background image.
Now, open the gnome-shell.css
file in the directory and change the #lockDialogGroup
definition as follows:
#lockDialogGroup { background: #2e3436 url(filename); background-size: [WIDTH]px [HEIGHT]px; background-repeat: no-repeat; }
Set background-size
to the resolution that GDM uses, this might not necessarily be the resolution of the image. For a list of display resolutions see Display resolution. Again, set filename to be the name of the background image.
Finally, compile the theme using the following command:
$ glib-compile-resources gnome-shell-theme.gresource.xml
Then copy the resulting gnome-shell-theme.gresource
file to the /usr/share/gnome-shell
directory.
Restart GDM - you should find that it is using your preferred background image.
For more information, please see the following forum thread.
Log-in screen logo
To display a logo on your log-in screen, follow the instructions below.
Create the directory to store the logo:
# mkdir /opt/login
Create the necessary configuration file:
# touch /etc/dconf/db/gdm.d/02-logo
Copy this text into the file:
[org/gnome/login-screen] logo='/opt/login/logo.png'
Copy your logo of choice into the directory:
# cp [YOUR FILE] /opt/login/logo.png
where [YOUR FILE] needs to be a path to a PNG image.
Update dconf:
# dconf update
Changing the GDM cursor theme
See Cursor themes#GDM.
Larger font for log-in screen
Click on the accessibility icon at the top right of the screen (a white circle with the silhouette of a person in the centre) and check the 'Large Text' option.
Alternatively, follow the instructions below:
Create the necessary configuration file:
# touch /etc/dconf/db/gdm.d/03-scaling
Copy this text into the file:
[org/gnome/desktop/interface] text-scaling-factor='1.25'
Update dconf:
# dconf update
Turning off the sound
This tweak disables the audible feedback heard when the system volume is adjusted (via keyboard) on the login screen.
Create the necessary configuration file:
# touch /etc/dconf/db/gdm.d/04-sound
Copy this text into the file:
[org/gnome/desktop/sound] event-sounds='false'
Update dconf:
# dconf update
Make the power button interactive
The default installation sets the power button to suspend the system. Power off or Show dialog is a better choice.
Create the necessary configuration file:
# touch /etc/dconf/db/gdm.d/05-power
Copy this text into the file:
[org/gnome/settings-daemon/plugins/power button] power='interactive' hibernate='interactive'
Update dconf:
# dconf update
Prevent suspend when closing the lid
Some laptops may experience behaviour where the laptop suspends when the lid is closed despite having set the options Laptop lid close action on battery and Laptop lid close action on AC to blank. If this is the case uncomment the HandleLidSwitch
line in the /etc/systemd/logind.conf
file and change the value to ignore
. The value is set to suspend
by default.
GDM keyboard layout
See Keyboard configuration in Xorg#Using X configuration files.
GNOME Control Center
If the package gnome-control-center is installed, the keyboard layout(s) can be configured using a grapical frontend:
Settings > Keyboard > Input Sources > Login Screen
GDM 2.x layout
Users of legacy GDM may need to follow the instructions below:
Edit ~/.dmrc
:
~/.dmrc
[Desktop] Language=de_DE.UTF-8 # change to your default lang Layout=de nodeadkeys # change to your keyboard layout
Change the language
To change the GDM language, edit the file /var/lib/AccountsService/users/gdm
and change the language line using the correct UTF-8 value for your language. You should see something similar to the text below:
/var/lib/AccountsService/users/gdm
[User] Language=fr_FR.UTF-8 XSession= SystemAccount=true
Now just reboot your computer.
Once you have rebooted, if you look at the /var/lib/AccountsService/users/gdm
file again, you will see that the language line is cleared — do not worry, the language change has been preserved.
Automatic login
To enable automatic login with GDM, add the following to /etc/gdm/custom.conf
(replace username with your own):
/etc/gdm/custom.conf
# Enable automatic login for user [daemon] AutomaticLogin=username AutomaticLoginEnable=True
or for an automatic login with a delay:
/etc/gdm/custom.conf
[daemon] TimedLoginEnable=true TimedLogin=username TimedLoginDelay=1
Passwordless login
If you want to bypass the password prompt in GDM then simply add the following line on the first line of /etc/pam.d/gdm-password
:
auth sufficient pam_succeed_if.so user ingroup nopasswdlogin
Then, add the group nopasswdlogin
to your system. See Groups for group descriptions and group management commands.
Now, add your user to the nopasswdlogin
group and you will only have to click on your username to login.
Passwordless shutdown for multiple sessions
GDM uses polkit and logind to gain permissions for shutdown. You can shutdown the system when multiple users are logged in by setting:
/etc/polkit-1/localauthority.conf.d/org.freedesktop.logind.policy
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE policyconfig PUBLIC "-//freedesktop//DTD PolicyKit Policy Configuration 1.0//EN" "http://www.freedesktop.org/standards/PolicyKit/1.0/policyconfig.dtd"> <policyconfig> <action id="org.freedesktop.login1.power-off-multiple-sessions"> <description>Shutdown the system when multiple users are logged in</description> <message>System policy prevents shutting down the system when other users are logged in</message> <defaults> <allow_inactive>yes</allow_inactive> <allow_active>yes</allow_active> </defaults> </action> </policyconfig>
You can find all available logind options (e.g. reboot-multiple-sessions) here.
Add or edit GDM sessions
Each session is a .desktop
file located at /usr/share/xsessions/
.
To add a new session:
1. Copy an existing .desktop
file to use as a template for a new session:
$ cd /usr/share/xsessions # cp gnome.desktop other.desktop
2. Modify the template .desktop
file to open the required window manager:
# nano other.desktop
If you happen to have KDM installed in parallel, you can alternatively open the new session in KDM which will create the new .desktop
file. Then return to using GDM and the new session will be available.
See also Display manager#Session list.
Enable root login in GDM
It is not advised to login as root, but if necessary you can edit /etc/pam.d/gdm-password
and add the following line before the line auth required pam_deny.so
:
/etc/pam.d/gdm-password
auth sufficient pam_succeed_if.so uid eq 0 quiet
The file should look something like this:
/etc/pam.d/gdm-password
... auth sufficient pam_succeed_if.so uid eq 0 quiet auth sufficient pam_succeed_if.so uid >= 1000 quiet auth required pam_deny.so ...
You should be able to login as root after restarting GDM.
Hide user from login list
The users for the gdm user list are gathered by accountsservice. It will automatically hide system users (UID < 1000).
To hide ordinary users from the login list create or edit a file named after the user to hide in /var/lib/AccountsService/users/
to contain at least:
/var/lib/AccountsService/users/<username>
[User] SystemAccount=true
Rotate login screen
If you have your monitors setup as you like (orientation, primary and so on) in ~/.config/monitors.xml
and want GDM to honor those settings:
# cp ~/.config/monitors.xml /var/lib/gdm/.config/monitors.xml
Changes will take effect on logout. This is necessary because GDM does not respect xorg.conf
.
xrandr at login
If you want to run a script using xrandr that affects the login screen you must add a script in /etc/X11/xinit/xinitrc.d
since GDM is not respecting or launching the scripts in /etc/gdm/Init
.
For example, to select automatically a external screen connected through HDMI:
extractgst.sh
#!/bin/sh EXTERNAL_OUTPUT="HDMI1" INTERNAL_OUTPUT="eDP1" if (xrandr | grep $EXTERNAL_OUTPUT | grep " connected "); then xrandr --output $INTERNAL_OUTPUT --off --output $EXTERNAL_OUTPUT --auto echo "extmonitor" >> /home/oscar/gdmtest else xrandr --output $INTERNAL_OUTPUT --auto fi
Configure X server access permission
You can use the xhost
command to configure X server access permissions.
For instance, to grant GDM the right to access the X server, use the following command:
# xhost +SI:localuser:gdm
Troubleshooting
Failure to start with AMD Catalyst driver
Downgrade the xorg-server package or try to use another display manager like LightDM.
Failure on logout
If GDM starts up properly on boot, but fails after repeated attempts on logout, try adding this line to the daemon section of /etc/gdm/custom.conf
:
GdmXserverTimeout=60
Xorg 1.16
See Xorg#Rootless Xorg (v1.16).
Use Xorg backend
As of GDM version 3.16, the Wayland backend is used by default and the Xorg backend is used only if the Wayland backend cannot be started. As the Wayland backend has been reported to cause problems for some users, use of the Xorg backend may be necessary. To use the Xorg backend by default, edit the /etc/gdm/custom.conf
file and uncomment the following line:
#WaylandEnable=false