Difference between revisions of "GDM"

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[[Category:Display managers]]
 
[[Category:Display managers]]
 +
[[Category:GNOME]]
 +
[[es:GDM]]
 +
[[ja:GDM]]
 
[[pt:GDM]]
 
[[pt:GDM]]
[[zh-CN:GDM]]
+
[[zh-hans:GDM]]
{{Article summary start}}
+
{{Related articles start}}
{{Article summary text|GDM is the GNOME Display Manager, a graphical login program. This article covers its installation and configuration.}}
+
{{Related|GNOME}}
{{Article summary heading|Related}}
+
{{Related|Display manager}}
{{Article summary wiki|Display Manager}}
+
{{Related articles end}}
{{Article summary wiki|Gnome}}
+
From [https://wiki.gnome.org/Projects/GDM GDM - GNOME Display Manager]: "The GNOME Display Manager (GDM) is a program that manages graphical display servers and handles graphical user logins."
{{Article summary end}}
 
  
From [http://projects.gnome.org/gdm/about.html GDM - GNOME Display Manager]:
+
[[Display manager]]s provide [[X Window System]] and [[Wayland]] users with a graphical login prompt.
  
:''GDM is the GNOME Display Manager, it is the little program that runs in the background, runs your X sessions, presents you with a login box and then tells you to bug off because you forgot your password. It does pretty much everything that you would want to use xdm for, but does not involve as much crack. It does not use any code from xdm. It supports XDMCP, and in fact extends XDMCP a little bit in places where I thought xdm was lacking (but is still compatible with xdm's XDMCP).''
+
== Installation ==
  
[[Display manager]]s provide [[X Window System]] users with a graphical login prompt.
+
GDM can be [[installed]] with the {{Pkg|gdm}} package, and it is installed as part of the {{grp|gnome}} group.
  
==Installation==
+
If you would prefer to use legacy GDM which was used in GNOME 2 and has its own configuration utility, install the {{AUR|gdm-old}} package. Note that the rest of this article discusses current GDM, not legacy GDM, unless indicated otherwise.
GDM (which is also part of {{Grp|gnome-extra}}) can be [[Pacman|Installed] with the {{Pkg|gdm}} package, available in the [[Official repositories]].
 
  
=== GDM as the default greeter ===
+
You might also wish to install the following:
 +
* {{App|gdm3setup|An interface to configure GDM3, autologin options and change Shell theme|https://github.com/Nano77/gdm3setup|{{AUR|gdm3setup-utils}}}}
  
{{Box Note|While this is currently still the default method, Arch Linux is in a transitional period between init solutions. Eventually, initscripts and sysvinit will be replaced with [[systemd]]. See below for systemd instructions if you are on a pure [[systemd]] solution already}}
+
== Starting ==
To make the graphical login the default method of logging into the system, edit your {{ic|/etc/inittab}} file). These procedures are detailed on the [[Display Manager]] page.
 
  
The arguments passed to the X server by {{ic|~/.xinitrc}} (such as those of {{ic|xmodmap}} and {{ic|xsetroot}}) can also be added through [[xprofile]]:
+
To start GDM at boot time [[enable]] {{ic|gdm.service}}.
  
{{hc|~/.xprofile|<nowiki>
+
=== Autostarting applications ===
 +
 
 +
One might want to autostart certain commands, such as ''xrandr'' for instance, on login. This can be achieved by adding a command or script to a location that is sourced by the display manager. See [[Display manager#Autostarting]] for a list of supported locations.
 +
{{Note|1=The {{ic|/etc/gdm/Init}} directory is no longer a supported location, see [https://bugzilla.gnome.org/show_bug.cgi?id=751602#c2].}}
 +
 
 +
== Configuration ==
 +
 
 +
=== Log-in screen background image ===
 +
 
 +
{{Note|
 +
* Since GNOME 3.16, GNOME Shell themes are now stored as binary files (gresource).
 +
* This change will be overwritten on subsequent updates of {{Pkg|gnome-shell}}.}}
 +
 
 +
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:
 +
 
 +
{{hc|extractgst.sh|2=
 
#!/bin/sh
 
#!/bin/sh
  
#
+
workdir=${HOME}/shell-theme
# ~/.xprofile
+
if [ ! -d ${workdir}/theme ]; then
#
+
  mkdir -p ${workdir}/theme
# Executed by gdm at login
+
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:
 +
 
 +
{{hc|gnome-shell-theme.gresource.xml|2=
 +
<?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-hc.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 {{ic|gnome-shell.css}} file in the directory and change the {{ic|#lockDialogGroup}} definition as follows:
 +
 
 +
#lockDialogGroup {
 +
  background: #2e3436 url('''filename''');
 +
  background-size: '''[WIDTH]'''px '''[HEIGHT]'''px;
 +
  background-repeat: no-repeat;
 +
}
 +
 
 +
Set {{ic|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 [[wikipedia:Display_resolution#Computer_monitors|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 {{ic|gnome-shell-theme.gresource}} file to the {{ic|/usr/share/gnome-shell}} directory.
 +
 
 +
Then restart {{ic|gdm.service}} (note that simply logging out is not enough) and you should find that it is using your preferred background image.
 +
 
 +
For more information, please see the following [https://bbs.archlinux.org/viewtopic.php?id&#61;197036 forum thread].
 +
 
 +
=== DConf configuration ===
 +
 
 +
Some GDM settings are stored in a DConf database. They can be configured either by adding ''keyfiles'' to the {{ic|/etc/dconf/db/gdm.d}} directory and then recompiling the GDM database by running {{ic|dconf update}} as root or by logging into the GDM user on the system and changing the setting directly using the ''gsettings'' command line tool. Note that for the former approach, a GDM profile file is required - this must be created manually as it is no longer shipped upstream, see below:
 +
{{hc|/etc/dconf/profile/gdm|
 +
user-db:user
 +
system-db:gdm
 +
file-db:/usr/share/gdm/greeter-dconf-defaults}}
 +
For the latter approach, you can log into the GDM user with the command below:
 +
# machinectl shell gdm@
 +
 
 +
==== Log-in screen logo ====
 +
 
 +
Either create the following keyfile
 +
{{hc|/etc/dconf/db/gdm.d/02-logo|2=
 +
[org/gnome/login-screen]
 +
logo=<nowiki>'</nowiki>''/path/to/logo.png''<nowiki>'</nowiki>}}
 +
and then recompile the GDM database or alternatively log in to the GDM user and execute the following:
 +
$ gsettings set org.gnome.login-screen logo <nowiki>'</nowiki>''/path/to/logo.png''<nowiki>'</nowiki>
 +
 
 +
==== Changing the cursor theme ====
  
xmodmap -e "pointer=1 2 3 6 7 4 5" # set mouse buttons up correctly
+
GDM disregards [[GNOME]] cursor theme settings and it also ignores the cursor theme set according to the [[Cursor themes#XDG specification|XDG specification]]. To change the cursor theme used in GDM, either create the following keyfile
xsetroot -solid black              # sets the background to black
 
</nowiki>}}
 
  
==== systemd method ====
+
{{hc|/etc/dconf/db/gdm.d/10-cursor-settings|
 +
<nowiki>[org/gnome/desktop/interface]
 +
cursor-theme='</nowiki>''theme-name'''
 +
}}
 +
and then recompile the GDM database or alternatively log in to the GDM user and execute the following:
 +
$ gsettings set org.gnome.desktop.interface cursor-theme <nowiki>'</nowiki>''theme-name''<nowiki>'</nowiki>
  
GDM comes packaged with a systemd service file, {{ic|gdm.service}}. Simply run the following command once to bring up GDM after on boot:
+
==== Larger font for log-in screen ====
systemctl enable gdm.service
 
  
You may want to consider adding {{ic|NetworkManager.service}} for the complete GNOME experience.
+
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.
systemctl enable NetworkManager.service
 
  
==Configuration==
+
To set a specific scaling factor, you can create the following keyfile:
You can no longer use the gdmsetup command to configure GDM as of version 2.28. The command has been removed and GDM has been standardized and integrated with the rest of GNOME.
+
{{hc|/etc/dconf/db/gdm.d/03-scaling|2=
 +
[org/gnome/desktop/interface]
 +
text-scaling-factor=<nowiki>'</nowiki>''1.25''<nowiki>'</nowiki>}}
 +
and then recompile the GDM database or alternatively log in to the GDM user and execute the following:
 +
$ gsettings set org.gnome.desktop.interface text-scaling-factor <nowiki>'</nowiki>''1.25''<nowiki>'</nowiki>
  
You can install {{aur|gdm3setup}} from the AUR to configure GDM, or use the following instructions.
+
==== Turning off the sound ====
  
Configure X server access permission:
+
This tweak disables the audible feedback heard when the system volume is adjusted (via keyboard) on the login screen.
{{bc|# xhost +SI:localuser:gdm}}
+
 
 +
Either create the following keyfile:
 +
{{hc|/etc/dconf/db/gdm.d/04-sound|2=
 +
[org/gnome/desktop/sound]
 +
event-sounds='false'}}
 +
and then recompile the GDM database or alternatively log in to the GDM user and execute the following:
 +
$ gsettings set org.gnome.desktop.sound event-sounds 'false'
 +
 
 +
==== Configure power button behavior ====
 +
 
 +
{{Note|1=<nowiki></nowiki>
 +
* The [[Power management#ACPI events|logind settings]] for the power button are overriden by GNOME Settings Daemon. [https://bugzilla.gnome.org/show_bug.cgi?id=755953#c4]
 +
* As of October 2015, the power button cannot be set to ''interactive''. [https://bugzilla.gnome.org/show_bug.cgi?id=753713#c6]
 +
* In some cases, this setting will be ignored and hardcoded defaults will be used. [https://bugzilla.gnome.org/show_bug.cgi?id=755953#c17]}}
 +
 
 +
{{Warning|Please note that the [[acpid]] daemon also handles the "power button" and "hibernate button" events. Running both systems at the same time may lead to unexpected behaviour.}}
 +
 
 +
Either create the following keyfile:
 +
{{hc|/etc/dconf/db/gdm.d/05-power|2=
 +
[org/gnome/settings-daemon/plugins/power]
 +
power-button-action=<nowiki>'</nowiki>''action''<nowiki>'</nowiki>}}
 +
and then recompile the GDM database or alternatively log in to the GDM user and execute the following:
 +
$ gsettings set org.gnome.settings-daemon.plugins.power power-button-action <nowiki>'</nowiki>''action''<nowiki>'</nowiki>
 +
where ''action'' can be one of {{ic|nothing}}, {{ic|suspend}} or {{ic|hibernate}}.
 +
 
 +
==== Enabling tap-to-click ====
 +
 
 +
Tap-to-click is disabled in GDM (and GNOME) by default, but you can easily enable it with a dconf setting.
 +
 
 +
{{Note|If you want to do this under X, you have to first set up correct X server access permissions - see [[#Configure X server access permission]].}}
 +
 
 +
To directly enable tap-to-click, use:
 +
 
 +
{{bc|# sudo -u gdm gsettings set org.gnome.desktop.peripherals.touchpad tap-to-click true}}
 +
 
 +
If you prefer to do this with a GUI, use:
 +
 
 +
{{bc|# sudo -u gdm dconf-editor}}
 +
 
 +
To check the if it was set correctly, use:
 +
 
 +
{{bc|$ sudo -u gdm gsettings get org.gnome.desktop.peripherals.touchpad tap-to-click}}
 +
 
 +
If you get the error {{ic|dconf-WARNING **: failed to commit changes to dconf: Error spawning command line}}, make sure dbus is running:
 +
 
 +
{{bc|$ sudo -u gdm dbus-launch gsettings set org.gnome.desktop.peripherals.touchpad tap-to-click true}}
 +
 
 +
==== Disable/Enable Accessibility Menu ====
 +
 
 +
To disable or enable the Accessibility Menu, set the following key in dconf editor:
 +
 
 +
{{bc|# machinectl shell gdm@
 +
# gsettings set org.gnome.desktop.interface toolkit-accessibility false
 +
# exit}}
 +
 
 +
The menu is disabled when the key is false, enabled when it is true.
 +
 
 +
=== Keyboard layout ===
 +
 
 +
See [[Keyboard configuration in Xorg#Using X configuration files]].
 +
 
 +
{{Tip|See [[Wikipedia:ISO 3166-1]] for a list of keymaps.}}
 +
 
 +
Alternatively, if the package {{Pkg|gnome-control-center}} is installed, the keyboard layout(s) can be configured using a graphical frontend. Start ''gnome-control-center'' and navigate to ''Region & Language -> Input Sources''. Then, in the header bar, hit the ''Login Screen'' toggle button to configure the keyboard layout for GDM specifically.
  
Change the theme:
+
Users of GDM 2.x (legacy GDM) may need to edit {{ic|~/.dmrc}} as shown below:
{{bc|$ sudo -u gdm dbus-launch gnome-control-center}}
 
  
For more configuration options, do:
+
{{hc|~/.dmrc|2=
{{bc|$ sudo -u gdm dbus-launch gconf-editor}}
+
[Desktop]
 +
Language=de_DE.UTF-8  # change to your default lang
 +
Layout=de  nodeadkeys # change to your keyboard layout
 +
}}
  
and modify the following hierarchies:
+
=== Change the language ===
/apps/gdm/simple-greeter
 
/desktop/gnome/interface
 
/desktop/gnome/background
 
  
If these commands fail with an error (e.g. {{ic|"Cannot open display"}}) you can bring the two windows up when GDM starts by adding them to GDM's autostart. To do this first create the entry:
+
To change the GDM language, ensure that {{Pkg|gnome-control-center}} is installed. Then, start ''gnome-control-center'' and choose ''Region & Language''. In the header bar, check the ''Login Screen'' toggle button. Finally, click on ''Language'' and choose your language from the list. You will be prompted for your root password.
{{bc|# cp -t /usr/share/gdm/autostart/LoginWindow/ /usr/share/applications/gnome-appearance-properties.desktop /usr/share/applications/gconf-editor.desktop}}
 
  
Then go back to GDM, do your changes and log back in. When you're done and want the window to stop opening with GDM run this:
+
{{Tip|By adding 2 different input languages, logging out then selecting your default language GDM will remember your choice once the second option is removed.}}
{{bc|# rm /usr/share/gdm/autostart/LoginWindow/gnome-appearance-properties.desktop /usr/share/gdm/autostart/LoginWindow/gconf-editor.desktop}}
 
  
{{Note|By using the logout/configure method you can view the changes while you're making them.}}
+
=== Users and login ===
  
For more information and advanced settings read [http://library.gnome.org/admin/gdm/stable/configuration.html.en this].
+
==== Automatic login ====
  
===Automatic login===
 
 
To enable automatic login with GDM, add the following to {{ic|/etc/gdm/custom.conf}} (replace ''username'' with your own):
 
To enable automatic login with GDM, add the following to {{ic|/etc/gdm/custom.conf}} (replace ''username'' with your own):
  
Line 84: Line 257:
 
AutomaticLoginEnable=True
 
AutomaticLoginEnable=True
 
}}
 
}}
 +
 +
{{Tip|If GDM fails after adding these lines, comment them out from a TTY.}}
  
 
or for an automatic login with a delay:
 
or for an automatic login with a delay:
Line 89: Line 264:
 
{{hc|1=/etc/gdm/custom.conf|
 
{{hc|1=/etc/gdm/custom.conf|
 
2=[daemon]
 
2=[daemon]
# for login with delay
+
 
 
TimedLoginEnable=true
 
TimedLoginEnable=true
 
TimedLogin=''username''
 
TimedLogin=''username''
Line 95: Line 270:
 
}}
 
}}
  
===Passwordless login===
+
You can set the session used for automatic login (replace {{ic|gnome-xorg}} with desired session):
If you want to bypass the password prompt in GDM then simply add the following line to {{ic|/etc/pam.d/gdm}}:
+
 
 +
{{hc|1=/var/lib/AccountsService/users/''username''|
 +
2=XSession=gnome-xorg
 +
}}
 +
 
 +
==== Passwordless login ====
 +
 
 +
If you want to bypass the password prompt in GDM then simply add the following line on the first line of {{ic|/etc/pam.d/gdm-password}}:
  
 
  auth sufficient pam_succeed_if.so user ingroup nopasswdlogin
 
  auth sufficient pam_succeed_if.so user ingroup nopasswdlogin
  
Make sure this line goes right '''before''' the {{ic|pam_unix.so}} {{ic|auth}} line.
+
Then, add the group {{ic|nopasswdlogin}} to your system. See [[Groups]] for group descriptions and group management commands.
  
Then, add the group {{ic|nopasswdlogin}} to your system. You can do it graphically in {{ic|System > Administration > Users and Groups}}. See [[Groups]] for group descriptions and group management commands.
+
Now, add your user to the {{ic|nopasswdlogin}} group and you will only have to click on your username to login.
  
Now, when you use {{ic|System > Administration > Users and Groups}} (command: {{ic|users-admin}}) and set your user for {{ic|"Password: not asked at login"}} (by checking the {{ic|"Don't ask for password on login"}} option), your user will be automatically added to the {{ic|nopasswdlogin}} group and you will only have to click on your username to login.
+
{{Warning|
  
{{Warning|Do '''not''' do this for a '''root''' account.}}
+
* Do '''not''' do this for a '''root''' account.
 +
* You won't be able to change your session type at login with GDM anymore. If you want to change your default session type, you will first need to remove your user from the {{ic|nopasswdlogin}} group.}}
  
===GDM legacy===
+
==== Passwordless shutdown for multiple sessions ====
If you want to fall back to the old GDM, which also has a tool for configuring its settings, compile and install {{aur|gdm-old}} from AUR.
 
  
==Troubleshooting==
+
GDM uses polkit and logind to gain permissions for shutdown. You can shutdown the system when multiple users are logged in by setting:
===GDM fails 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 {{ic|/etc/gdm/custom.conf}}:
+
{{hc|1=/etc/polkit-1/localauthority.conf.d/org.freedesktop.logind.policy|
  GdmXserverTimeout=60
+
2=<?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">
 +
 
 +
<!--
 +
Policy definitions for logind
 +
  -->
 +
 
 +
<policyconfig>
  
===gconf-sanity-check-2 exited with status 256===
+
  <action id="org.freedesktop.login1.power-off-multiple-sessions">
If GDM pops up an error about {{ic|gconf-sanity-check-2}}, you may check permissions in {{ic|/home}} and {{ic|/etc/gconf/gconf.xml.system}} (the latter should be {{ic|755}}).
+
    <description>Shutdown the system when multiple users are logged in</description>
If GDM is still printing the message, try to empty the gdm home. Run as root:
+
    <message>System policy prevents shutting down the system when other users are logged in</message>
rm -rf /var/lib/gdm/.*
+
    <defaults>
 +
      <allow_inactive>yes</allow_inactive>
 +
      <allow_active>yes</allow_active>
 +
    </defaults>
 +
  </action>
  
If that doesn't help, try to set {{ic|/tmp}} owner and permissions to:
+
</policyconfig>
# chown -R root:root /tmp
+
}}
# chmod 777 /tmp
+
You can find all available logind options (e.g. reboot-multiple-sessions) [http://www.freedesktop.org/wiki/Software/systemd/logind#Security here].
 +
 
 +
==== Enable root login in GDM ====
  
===GDM root login===
 
 
It is not advised to login as root, but if necessary you can edit {{ic|/etc/pam.d/gdm-password}} and add the following line before the line {{ic|auth required pam_deny.so}}:
 
It is not advised to login as root, but if necessary you can edit {{ic|/etc/pam.d/gdm-password}} and add the following line before the line {{ic|auth required pam_deny.so}}:
 +
 
{{ic|/etc/pam.d/gdm-password}}
 
{{ic|/etc/pam.d/gdm-password}}
 +
 
  auth            sufficient      pam_succeed_if.so uid eq 0 quiet
 
  auth            sufficient      pam_succeed_if.so uid eq 0 quiet
  
 
The file should look something like this:
 
The file should look something like this:
 +
 
{{ic|/etc/pam.d/gdm-password}}
 
{{ic|/etc/pam.d/gdm-password}}
 +
 
  ...
 
  ...
 
  auth            sufficient      pam_succeed_if.so uid eq 0 quiet
 
  auth            sufficient      pam_succeed_if.so uid eq 0 quiet
Line 140: Line 340:
 
You should be able to login as root after restarting GDM.
 
You should be able to login as root after restarting GDM.
  
===GDM always uses default US-keyboard===
+
==== Hide user from login list ====
Problem: Keyboard layout always switches to us; layout is reset when a new keyboard is plugged in.
+
 
 +
The users for the gdm user list are gathered by [https://www.freedesktop.org/wiki/Software/AccountsService/ 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 {{ic|/var/lib/AccountsService/users/}} to contain at least:
 +
{{hc|/var/lib/AccountsService/users/<nowiki><username></nowiki>|
 +
[User]
 +
<nowiki>SystemAccount=true</nowiki>}}
 +
 
 +
=== Setup default monitor settings ===
 +
 
 +
Some [[desktop environments]] store display settings in {{ic|~/.config/monitors.xml}}. ''xrandr'' commands are then generated on the base of the file content. GDM has a similar file stored in {{ic|/var/lib/gdm/.config/monitors.xml}}.   
 +
 
 +
If you have your monitors setup as you like (orientation, primary and so on) in {{ic|~/.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 {{ic|xorg.conf}}.
 +
 
 +
{{Note|Wayland backend may be [https://bbs.archlinux.org/viewtopic.php?id&#61;196219 ignoring] {{ic|/var/lib/gdm/.config/monitors.xml}} file. See [[#Use Xorg backend]] to learn how to disable Wayland backend.}}
 +
 
 +
=== Configure X server access permission ===
 +
 
 +
You can use the {{ic|xhost}} command to configure X server access permissions.
 +
 
 +
For instance, to grant GDM the right to access the X server, use the following command:
  
====GDM 2.x====
+
{{bc|# xhost +SI:localuser:gdm}}
Solution:
+
 
edit {{ic|~/.dmrc}}
+
== Troubleshooting ==
{{hc|~/.dmrc|2=
+
 
[Desktop]
+
=== Failure to start with AMD Catalyst driver ===
Language=de_DE.UTF-8  # change to your default lang
+
Downgrade the {{pkg|xorg-server}} package or try to use another [[display manager]] like [[LightDM]].
Layout=de  nodeadkeys # change to your keyboard layout
+
 
}}
+
=== 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 {{ic|/etc/gdm/custom.conf}}:
  
====GDM 3.x====
+
GdmXserverTimeout=60
Solution:
 
add the following line to {{ic|/etc/X11/xorg.conf.d/10-evdev.conf}}, replacing fr with the appropriate keymap
 
{{hc|/etc/X11/xorg.conf.d/10-evdev.conf|
 
Section "InputClass"
 
        Identifier "evdev keyboard catchall"
 
        MatchIsKeyboard "on"
 
        MatchDevicePath "/dev/input/event*"
 
        Driver "evdev"
 
        '''Option "XkbLayout" "fr"'''
 
EndSection}}
 
  
{{Warning|Add the line to the {{ic|'''keyboard''' InputClass}} section, not the pointer one.}}
+
=== Rootless Xorg ===
  
====GDM Will Not Load After Attempting to Set-Up Automatic Login====
+
See [[Xorg#Rootless Xorg]].
  
To solve this issue, edit /etc/gdm/custom.conf from a TTY and comment "AutomaticLoginEnable" and the "AutomaticLogin" lines.
+
=== Use Xorg backend ===
  
{{bc|1=# GDM configuration storage
+
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 [https://bugzilla.redhat.com/show_bug.cgi?id=1199890 reported] to cause problems for some users, use of the Xorg backend may be necessary. To use the Xorg backend by default, edit the {{ic|/etc/gdm/custom.conf}} file and uncomment the following line:
 +
#WaylandEnable=false
  
[daemon]
+
=== Incomplete removal of gdm ===
  
#AutomaticLoginEnable=True
+
After removing {{Pkg|gdm}}, [[systemd]] may report the following:
#AutomaticLogin=user
 
  
[security]
+
user 'gdm': directory '/var/lib/gdm' does not exist
  
[xdmcp]
+
To remove this warning, login as root and delete the primary user "gdm" and then delete the group "gdm":
  
[greeter]
+
# userdel gdm
 +
# groupdel gdm
  
[chooser]
+
Verify that gdm is successfully removed via {{ic|pwck}} and {{ic|grpck}}. To round it off, you may want to double-check no [[Pacman/Tips_and_tricks#Identify_files_not_owned_by_any_package|unowned files]] for gdm remain.
  
[debug]
+
== See also ==
  
EndSection}}
+
* [https://help.gnome.org/admin/gdm/stable/index.html.en GDM Reference Manual]

Latest revision as of 16:46, 25 November 2017

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 and Wayland users with a graphical login prompt.

Installation

GDM can be installed with the gdm package, and it is installed as part of the gnome group.

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
https://github.com/Nano77/gdm3setup || gdm3setup-utilsAUR

Starting

To start GDM at boot time enable gdm.service.

Autostarting applications

One might want to autostart certain commands, such as xrandr for instance, on login. This can be achieved by adding a command or script to a location that is sourced by the display manager. See Display manager#Autostarting for a list of supported locations.

Note: The /etc/gdm/Init directory is no longer a supported location, see [1].

Configuration

Log-in screen background image

Note:
  • Since GNOME 3.16, GNOME Shell themes are now stored as binary files (gresource).
  • This change will be overwritten on subsequent updates of gnome-shell.

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-hc.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.

Then restart gdm.service (note that simply logging out is not enough) and you should find that it is using your preferred background image.

For more information, please see the following forum thread.

DConf configuration

Some GDM settings are stored in a DConf database. They can be configured either by adding keyfiles to the /etc/dconf/db/gdm.d directory and then recompiling the GDM database by running dconf update as root or by logging into the GDM user on the system and changing the setting directly using the gsettings command line tool. Note that for the former approach, a GDM profile file is required - this must be created manually as it is no longer shipped upstream, see below:

/etc/dconf/profile/gdm
user-db:user
system-db:gdm
file-db:/usr/share/gdm/greeter-dconf-defaults

For the latter approach, you can log into the GDM user with the command below:

# machinectl shell gdm@

Either create the following keyfile

/etc/dconf/db/gdm.d/02-logo
[org/gnome/login-screen]
logo='/path/to/logo.png'

and then recompile the GDM database or alternatively log in to the GDM user and execute the following:

$ gsettings set org.gnome.login-screen logo '/path/to/logo.png'

Changing the cursor theme

GDM disregards GNOME cursor theme settings and it also ignores the cursor theme set according to the XDG specification. To change the cursor theme used in GDM, either create the following keyfile

/etc/dconf/db/gdm.d/10-cursor-settings
[org/gnome/desktop/interface]
cursor-theme='theme-name'

and then recompile the GDM database or alternatively log in to the GDM user and execute the following:

$ gsettings set org.gnome.desktop.interface cursor-theme 'theme-name'

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.

To set a specific scaling factor, you can create the following keyfile:

/etc/dconf/db/gdm.d/03-scaling
[org/gnome/desktop/interface]
text-scaling-factor='1.25'

and then recompile the GDM database or alternatively log in to the GDM user and execute the following:

$ gsettings set org.gnome.desktop.interface text-scaling-factor '1.25'

Turning off the sound

This tweak disables the audible feedback heard when the system volume is adjusted (via keyboard) on the login screen.

Either create the following keyfile:

/etc/dconf/db/gdm.d/04-sound
[org/gnome/desktop/sound]
event-sounds='false'

and then recompile the GDM database or alternatively log in to the GDM user and execute the following:

$ gsettings set org.gnome.desktop.sound event-sounds 'false'

Configure power button behavior

Note:
  • The logind settings for the power button are overriden by GNOME Settings Daemon. [2]
  • As of October 2015, the power button cannot be set to interactive. [3]
  • In some cases, this setting will be ignored and hardcoded defaults will be used. [4]
Warning: Please note that the acpid daemon also handles the "power button" and "hibernate button" events. Running both systems at the same time may lead to unexpected behaviour.

Either create the following keyfile:

/etc/dconf/db/gdm.d/05-power
[org/gnome/settings-daemon/plugins/power]
power-button-action='action'

and then recompile the GDM database or alternatively log in to the GDM user and execute the following:

$ gsettings set org.gnome.settings-daemon.plugins.power power-button-action 'action'

where action can be one of nothing, suspend or hibernate.

Enabling tap-to-click

Tap-to-click is disabled in GDM (and GNOME) by default, but you can easily enable it with a dconf setting.

Note: If you want to do this under X, you have to first set up correct X server access permissions - see #Configure X server access permission.

To directly enable tap-to-click, use:

# sudo -u gdm gsettings set org.gnome.desktop.peripherals.touchpad tap-to-click true

If you prefer to do this with a GUI, use:

# sudo -u gdm dconf-editor

To check the if it was set correctly, use:

$ sudo -u gdm gsettings get org.gnome.desktop.peripherals.touchpad tap-to-click

If you get the error dconf-WARNING **: failed to commit changes to dconf: Error spawning command line, make sure dbus is running:

$ sudo -u gdm dbus-launch gsettings set org.gnome.desktop.peripherals.touchpad tap-to-click true

Disable/Enable Accessibility Menu

To disable or enable the Accessibility Menu, set the following key in dconf editor:

# machinectl shell gdm@
# gsettings set org.gnome.desktop.interface toolkit-accessibility false
# exit

The menu is disabled when the key is false, enabled when it is true.

Keyboard layout

See Keyboard configuration in Xorg#Using X configuration files.

Tip: See Wikipedia:ISO 3166-1 for a list of keymaps.

Alternatively, if the package gnome-control-center is installed, the keyboard layout(s) can be configured using a graphical frontend. Start gnome-control-center and navigate to Region & Language -> Input Sources. Then, in the header bar, hit the Login Screen toggle button to configure the keyboard layout for GDM specifically.

Users of GDM 2.x (legacy GDM) may need to edit ~/.dmrc as shown below:

~/.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, ensure that gnome-control-center is installed. Then, start gnome-control-center and choose Region & Language. In the header bar, check the Login Screen toggle button. Finally, click on Language and choose your language from the list. You will be prompted for your root password.

Tip: By adding 2 different input languages, logging out then selecting your default language GDM will remember your choice once the second option is removed.

Users and login

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
Tip: If GDM fails after adding these lines, comment them out from a TTY.

or for an automatic login with a delay:

/etc/gdm/custom.conf
[daemon]

TimedLoginEnable=true
TimedLogin=username
TimedLoginDelay=1

You can set the session used for automatic login (replace gnome-xorg with desired session):

/var/lib/AccountsService/users/username
XSession=gnome-xorg

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.

Warning:
  • Do not do this for a root account.
  • You won't be able to change your session type at login with GDM anymore. If you want to change your default session type, you will first need to remove your user from the nopasswdlogin group.

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.

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

Setup default monitor settings

Some desktop environments store display settings in ~/.config/monitors.xml. xrandr commands are then generated on the base of the file content. GDM has a similar file stored in /var/lib/gdm/.config/monitors.xml.

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.

Note: Wayland backend may be ignoring /var/lib/gdm/.config/monitors.xml file. See #Use Xorg backend to learn how to disable Wayland backend.

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

Rootless Xorg

See Xorg#Rootless Xorg.

Use Xorg backend

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

Incomplete removal of gdm

After removing gdm, systemd may report the following:

user 'gdm': directory '/var/lib/gdm' does not exist

To remove this warning, login as root and delete the primary user "gdm" and then delete the group "gdm":

# userdel gdm
# groupdel gdm

Verify that gdm is successfully removed via pwck and grpck. To round it off, you may want to double-check no unowned files for gdm remain.

See also