GDM-42.0

Introduction to GDM

GDM is a system service that is responsible for providing graphical logins and managing local and remote displays.

[Note]

Note

Development versions of BLFS may not build or run some packages properly if dependencies have been updated since the most recent stable versions of the book.

Package Information

GDM Dependencies

Required

AccountsService-22.08.8, GTK+-3.24.34, ISO Codes-4.11.0, itstool-2.0.7, libcanberra-0.30, libdaemon-0.14, and Linux-PAM-1.5.2

Optional

keyutils-1.6.1

Runtime Dependencies

gnome-session-42.0, gnome-shell-42.3.1, and elogind-246.10

User Notes: https://wiki.linuxfromscratch.org/blfs/wiki/gdm

Installation of GDM

It is recommended to have a dedicated user and group to take control of the gdm daemon after it is started. Issue the following commands as the root user:

groupadd -g 21 gdm &&
useradd -c "GDM Daemon Owner" -d /var/lib/gdm -u 21 \
        -g gdm -s /bin/false gdm &&
passwd -ql gdm

First, adapt GDM to build without systemd present:

sed -i -r '/(^| )systemd_dep/d' meson.build

Install GDM by running the following commands:

sed -e 's@systemd@elogind@'                                \
    -e '/elogind/isession  required       pam_loginuid.so' \
    -i data/pam-lfs/gdm-launch-environment.pam &&

mkdir build &&
cd    build &&

meson --prefix=/usr               \
      --buildtype=release         \
      -Dgdm-xsession=true         \
      -Dsystemd-journal=false     \
      -Dsystemdsystemunitdir=/tmp \
      -Dsystemduserunitdir=/tmp   .. &&
ninja

This package does not come with a usable test suite.

Now, as the root user:

ninja install &&
rm -rv /tmp/*.{service,target.d}

Command Explanations

--buildtype=release: Specify a buildtype suitable for stable releases of the package, as the default may produce unoptimized binaries.

-Dinitial-vt=7: Use this switch to make GDM start on VT7 instead of the first free VT.

-Ddefault-pam-config=lfs: Use this switch if you did not create the /etc/lfs-release file or distribution auto detection will fail and you will be unable to use GDM.

-Dgdm-xsession=true: This enables the installation of the GDM Xsession file.

Configuring GDM

Config Files

/etc/gdm/custom.conf

Configuration Information

The GDM daemon is configured using the /etc/gdm/custom.conf file. Default values are stored in GSettings in the gdm.schemas file. It is recommended that end-users modify the /etc/gdm/custom.conf file because the schemas file may be overwritten when the user updates their system to have a newer version of GDM.

Boot Script

To start gdm automatically when the system is switched to runlevel 5, install the /etc/rc.d/init.d/xdm script and the /etc/sysconfig/xdm configuration file included in the blfs-bootscripts-20220722 package and adjust /etc/inittab by running as the root user:

make install-gdm

In order to permanently set the default runlevel to 5, starting the gdm greeter screen automatically, you can modify /etc/inittab. As the root user:

sed /initdefault/s/3/5/ -i /etc/inittab

Contents

Installed Programs: gdm, gdmflexiserver, and gdm-screenshot
Installed Libraries: libgdm.so and pam_gdm.so (PAM Module)
Installed Directories: /etc/gdm, /usr/include/gdm, /usr/share/gdm, and /usr/share/help/*/gdm

Short Descriptions

gdm

is a login prompt for GNOME

gdm-screenshot

is a screenshot tool for GDM