Getting gnome to work after an initial CentOS installation

While preparing for my RHCE exam, I wanted to install of the system-config-* GUIs to see what functionality they provided. I used the yum groupinstall option to install the GNOME desktop:

$ yum groupinstall ‘GNOME Desktop Environment’

and then proceeded to add my preferred desktop environment to /etc/sysconfig/desktop:

$ cat /etc/sysconfig/desktop
DISPLAYMANAGER=”GNOME”

Once these items were installed I ran ‘init 5’ and was greeted with the following message in /var/log/messages:

init:x respawning too fast, disabled for 5 minutes.

After reading through various logs and scripts, I noticed that the gdm display manager wasn’t installed. I thought groupinstalling the GNOME desktop would force a display manager to be installed, but alas that isn’t the case. To get everything working I fired up yum and installed gdm:

$ yum install gdm

Everything worked as expected once gdm was installed, and I could fire up the GUIs without issue.

Monitoring DBUS events

While debugging a goofy GNOME / USB interoperability issue this week, I came across the dbus-monitor program. Dbus-monitor allows you to view messages as they are sent on the DBUS message bus, which can be amazingly useful for debugging hardware and software interoperability issues. To print the messages that are traveling on the system message bus (DBUS defines two types of buses, one is the system bus, the other is a per session bus), dbus-monitor can be run with the “-system” option:

$ dbus-monitor –system

signal sender=org.freedesktop.DBus -> dest=:1.4 interface=org.freedesktop.DBus; member=NameAcquired
 0 string ":1.4"
signal sender=:1.0 -> dest=(null destination) interface=org.freedesktop.Hal.Manager; member=DeviceRemoved
 0 string "/org/freedesktop/Hal/devices/volume_label_"
signal sender=:1.0 -> dest=(null destination) interface=org.freedesktop.Hal.Manager; member=DeviceAdded
 0 string "/org/freedesktop/Hal/devices/volume_label_"

In this example, you can see that two message were sent when a hardware device was added and removed from the system. After reading through a slew of documentation, I am finally starting to understand how all of the GNOME packages tie in one another. Yikes!