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<TITLE>Linux Configuration and Installation:Installing and Configuring XFree86</TITLE>
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<!--ISBN=1558285660//-->
<!--TITLE=Linux Configuration and Installation//-->
<!--AUTHOR=Patrick Volkerding//-->
<!--AUTHOR=Kevin Reichard//-->
<!--AUTHOR=Eric Foster//-->
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<P><BR></P>
<H4 ALIGN="LEFT"><A NAME="Heading30"></A><FONT COLOR="#000077">UNIX Run-Levels</FONT></H4>
<P><B>Xdm</B> is usually set to trigger what is called a <I>run-level</I>. With a few exceptions, run-levels in UNIX is an arbitrary concept that mostly follows ancient UNIX traditions. The run-level <I>S</I> implies a single-user stand-alone system.</P>
<P>In Linux, run-level 1 and higher are multiuser. This means that more than one user is allowed to login. On many systems, run-level 3 starts networking. This is also the default Linux run-level. Linux has special run-levels for power-fail (which shuts the system down) and the Vulcan death-grip (<B>Ctrl-Alt-Backspace</B>).</P>
<P>You can get some ideas about run-levels by looking in the <B>/etc/inittab</B> file. In <B>/etc/inittab</B>, one of the first entries will be something like the following:</P>
<!-- CODE SNIP //-->
<PRE>
# Default runlevel.
id:3:initdefault:
</PRE>
<!-- END CODE SNIP //-->
<BLOCKQUOTE>
<P><FONT SIZE="-1"><HR><B>NOTE: </B>In Slackware 2.3 (and the first edition of this book), the Linux default run-level was 5. The default X run-level was 6. It has changed to 3 and 4, respectively. Now, run-level 6 will reboot the system, a great surprise if you want it to run X.<HR></FONT>
</BLOCKQUOTE>
<P>This states that the default system run-level is 3. When Linux boots up, it will boot into run-level 3. Later in the <B>/etc/inittab</B> file, you’ll find something like:</P>
<!-- CODE SNIP //-->
<PRE>
x1:4:wait:/etc/rc.d/rc.4
</PRE>
<!-- END CODE SNIP //-->
<P>This states that on entry to run-level 4, <B>/etc/rc.d/rc.4</B> should be run. This file, then, starts up the X Display Manager, which presents an X login screen.</P>
<P>On our system, <B>/etc/rc.d/rc.4</B> starts the following program:</P>
<!-- CODE SNIP //-->
<PRE>
# Tell the viewers what's going to happen...
echo "Starting up the X Window System V.11 R.6..."
# Call the "xdm" program.
exec /usr/X11R6/bin/xdm -nodaemon
</PRE>
<!-- END CODE SNIP //-->
<P>This is what starts up <B>xdm</B>. To get <B>xdm</B> up and running, all you should really have to do is edit the <B>/etc/inittab</B> as <B>root</B> and change the following line:</P>
<!-- CODE SNIP //-->
<PRE>
id:3:initdefault:
</PRE>
<!-- END CODE SNIP //-->
<P>to
</P>
<!-- CODE SNIP //-->
<PRE>
id:4:initdefault:
</PRE>
<!-- END CODE SNIP //-->
<P>That’s it. Everything else comes preconfigured. You may want to change the configuration, but you have a good start.
</P>
<P>After making these changes, when you next boot Linux, you’ll boot into run-level 4 rather than run-level 3. The process of going into run-level 4 will start <B>xdm</B>, because of what’s in the <B>/etc/rc.d/rc.4</B> file.</P>
<P>Before doing this, though, make a copy of <B>/etc/inittab</B>. You also should test <B>xdm</B> before setting the system to boot into it, because you always want to be able to boot Linux. (Making a mistake in <B>/etc/inittab</B> can result in a Linux that won’t boot.) To test <B>xdm</B>, you can type in the following command as root, to change to run-level 4 now:</P>
<!-- CODE SNIP //-->
<PRE>
# init 4
</PRE>
<!-- END CODE SNIP //-->
<P>This will jump you to run-level 4. Be patient; this command takes a while.
</P>
<P>Be sure that X is not running when you do this. You should be logged in as root at the console.</P>
<P>If you set up your <B>.login</B> or <B>.profile</B> file to automatically call <B>startx</B> when you login (see “Starting X Automatically on Login” later), you must disable this first. These two methods for starting X conflict. Quit X and then comment out those lines you added to the <B>.login</B> or <B>.profile</B> file, for example:</P>
<!-- CODE SNIP //-->
<PRE>
if ( `tty` == '/dev/tty1' ) then
# Commented out.
# startx
endif
</PRE>
<!-- END CODE SNIP //-->
<P>After a while, you should see a graphical login screen. It is best to test <B>xdm</B> using init 4 first, to see if everything is set up correctly. Try to login and see what happens. If it works, you’re in business and you can confidently modify the <B>/etc/inittab</B> file.</P>
<P>The <B>xdm</B> configuration files are in <B>/usr/lib/X11/xdm</B>. If you want to change the background color for the login screen, look in <B>Xsetup_0</B> in that directory. You probably won’t have to edit much <B>in /usr/lib/X11/xdm</B>, especially for a stand-alone Linux system without X terminals on the network. (If your needs are more demanding, you’ll need to look into a book on X, such as <I>The UNIX System Administrator’s Guide to X</I>; see Appendix A for more on this.)</P>
<H4 ALIGN="LEFT"><A NAME="Heading31"></A><FONT COLOR="#000077">User Accounts Under Xdm</FONT></H4>
<P>While you probably won’t have to edit any of the <B>xdm</B> system files in <B>/usr/lib/X11/xdm</B>, it’s likely you’ll have to edit files in your home directory. By default, <B>xdm</B> runs a file named <B>.xsession</B> from your home directory, instead of the <B>.xinitrc</B> that is run by <B>startx</B> (and <B>xinit</B>).</P>
<P>To create the <B>.xsession</B> file, you can start by copying your <B>.xinitrc</B> file to <B>.xsession</B> in your home directory. (Remember to put in the leading period on the filename in your home directory.) Then modify this file like you changed the <B>.xinitrc</B> file.</P>
<P>Here’s a copy of our <B>.xsession</B> file:</P>
<!-- CODE //-->
<PRE>
#!/bin/sh
userresources=$HOME/.Xresources
usermodmap=$HOME/.Xmodmap
sysresources=/usr/X11R6/lib/X11/xinit/.Xresources
sysmodmap=/usr/X11R6/lib/X11/xinit/.Xmodmap
# merge in defaults and keymaps
if [ -f $sysresources ]; then
xrdb -merge $sysresources
fi
if [ -f $sysmodmap ]; then
xmodmap $sysmodmap
fi
if [ -f $userresources ]; then
xrdb -merge $userresources
fi
if [ -f $usermodmap ]; then
xmodmap $usermodmap
fi
# start some nice programs
xsetroot -solid SteelBlue
xterm -geom 80x32+264+0 -ls &
xterm -geom 80x32+0+250 -ls &
oclock -geom -7-7 &
exec fvwm
</PRE>
<!-- END CODE //-->
<P>If you don’t want to start up X at boot time, you may want to start X every time you login.
</P><P><BR></P>
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