XWN740
X-Windows
Configuring and Using
Starting X Windows
(Chapter 2: Pages 25 – 39 )
Agenda
Starting X Windows

Virtual Terminals

Enabling/Disabling Display Manager at Boot

startx

Starting Multiple Servers

Working in X Without a Mouse

Terminating X Windows Session
Starting X Windows
Review from Last Week:
We mentioned last week
that only first two layers
of diagram are required,
and we can mix and match
other layers...
We will now see how this
can be done...
Starting X Windows
Virtual Terminals in X



Linux, FreeBSD, and many other modern Unix kernels support
a virtual terminal (VT) (or virtual console) capability, which
provides independent virtual video cards.
The monitor, keyboard, mouse, and physical video card are
associated with only one VT at a time, and each virtual video
card can be in a different display mode.
Some of these terminals are in text mode, others in graphical
mode. Learning how to access these modes can be very
useful...
Starting X Windows
Virtual Terminals in X



To switch virtual terminals, press <CTRL><ALT><Fx>, where
Fx is a function key F1 through F12.
If you are currently in a virtual terminal you can then press
<ALT><Fx> if the current virtual terminal is in text mode.
Keys <ALT><Right Arrow> and <ALT><Left Arrow> to move to
next / previous X server if you are in display NOT running X
Windows server.
Starting X Windows
Virtual Terminals in X

Virtual Terminals 1 – 6 (Text Based).

Virtual Terminals 7 – 12 (Graphical).

These rules may may depend on Linux Distro
Starting X Windows
Starting X Windows Server
Manual Start
Disadvantage:

No client(s) are started – only root window.
Must start client applications manually
Advantage:

Precise control over X server startup options
(i.e. Just run the client program you want – eg. kiosk)
Starting X Windows
Starting X Windows Server
Manual Start
Examples:
X :1
X :2 & sleep 2 ; DISPLAY=2 xeyes
X :1 -terminate & sleep 2;DISPLAY=:1 xterm
X Windows server terminates upon
client app terminating
Starting X Windows
Starting X Windows Server
Manual Start with Display Manager
Examples:
init 3
startx
Used to set run level to text-based
mode with network support
(init 5 sets to graphical with network)
Starting X Windows
Permanently Change Runlevel
To permanently change the default runlevel, add the following
line in the /etc/initab file:
id:5:initdefault:
or
id:3:initdefault:
Debian based systems (eg Ubuntu)
have different methods...
Starting X Windows
Manually Starting X Windows:
Using startx command
Purpose

The xinit utility can be used to start an X server with specified
clients, but the startx wrapper script provides a friendlier
interface. Also, as sys admin, runlevel 3 is avoids further
overhead of X Windows system unless required every now
and then....
Examples:

startx

startx -- :1

startx /usr/bin/xterm -bg yellow -geometry 180x50 --:1
Starting X Windows
What Starts the Display Manager Automatically?


Depending on your system configuration, the display manager may
be started directly by init, or through an init script. It's useful to
know how the display manager starts so that you can make changes
and so that you know what will happen if the display manager exits
(or crashes!).
In some Linux distributions, the display manager is directly started
by init. For example, in Fedora's /etc/inittab, you will find this entry:
# Run xdm in runlevel 5
x:5:respawn:/etc/X11/prefdm -nodaemon
Starting X Windows
What Starts the Display Manager Automatically?


Some Linux distributions use startup scripts to execute the display
manager.
Similar to the prefdm script used by Fedora, this script finds your
preferred display manager using a configuration file—in this case,
/etc/sysconfig/displaymanager—or it uses XDM if that file is
missing.
Starting X Windows
AUTOMATIC CONFIGURATION (MULTIPLE X SERVERS)
XDM (Xt)


XDM and older versions of KDM (pre-3.4) use the Xservers file to
configure the number of servers started by the display manager.
The location of this file varies; try /etc/X11/xdm/Xservers or
/opt/kde3/share/config/kdm/Xservers.
To start additional X servers, simply add lines at the bottom of
this file:
:1 local /usr/bin/X :1 vt8
:2 local /usr/bin/X :2 vt9
Starting X Windows
KDM (Qt)

If you're using KDE 3.4 or higher, the local X server configuration
is controlled by the kdmrc file (/etc/X11/xdm/kdmrc or
/opt/kde3/share/config/kdm/kdmrc). In the [General] section of
that file, you can specify a list of local displays to be started by
adding a StaticServers key:
StaticServers=:0,:1,:2
Starting X Windows
GDM (GTK+)

GDM is configured using two files; the first specifies default
values, which may be overwritten when GDM is updated, and the
second provides local values, which are never overwritten. The
name and location of these files varies; on an Ubuntu system, the
defaults are in /etc/gdm/gdm.conf and the local settings are in
/etc/gdm/gdm-custom.conf, while on a Fedora system, the
defaults are in /usr/share/gdm/defaults.conf and the local
settings are in /etc/gdm/custom.conf.
Starting X Windows
GDM (GTK+)

There are two sections in the GDM default configuration file that
deal with local X servers. The first defines the command to be
used to start a new server, and it looks like this:
[server-Standard]
name=Standard server
command=/usr/bin/X
flexible=true

This will start a single server with a display number of :0. To
configure GDM to initially start additional servers with the same
configuration, add a servers section to the local configuration file:
[servers]
0=Standard
1=Standard
2=Standard
Starting X Windows
Pointing without Mouse in X Windows
Purpose



Useful to know there is a
method to use pointer
if mouse is not working
Press <SHIFT><NUMLOCK>
to toggle mouse keys mode
Unavailable on keyboards
that do not have NUMERIC keys
Terminating X Windows
FROM COMMAND LINE:
Can use the killall command
Examples:

Killall X

Killall xdm

Killall kdm

Killall gdm-binary
Killing display
manager has benefit
of still running X
Terminating X Windows
Terminating X Windows Session
Within Graphical Session
When the server is hopelessly messed up, zapping it may be
your only available option short of a hard reset—and it is safe to
do when no clients are connected


Press <CTRL><ALT><BACKSPACE>
to toggle mouse keys mode
Disadvantage:

Any work-in-progress may be lost, and files may be left
in an indeterminate state.