Gratuitous Window Dressing, Part 3

Let me first begin with this brief
non-paid, non-political statement. Ahem...I was the victim of an
outdated style guide! Thanks to everyone who helpfully pointed out
that it is X window and not
X-Windows. I appreciate that you
took the time to write and try to save me some embarrassment. As it
turns out, I already knew this, but my last two columns were
corrected according to a somewhat flawed
editorial style guide. Last I heard, the Linux
Journal staff were holding a bonfire and roasting
marshmallows on said guide. [Sorry about that Marcel.--Ed.]But we were talking about not getting enough (X,
that is), so let me get back to this. In order to
explore this state of more, you
will need to be able to log in and out of X fairly readily. If you
use a login manager like xdm, gdm or kdm, you might want to start
your desktop with startx instead.
Then, when you leave X, you return to a text console and a command
prompt. On my Red Hat system, I can decide to use the graphical
login manager (or not) based on this entry in my
/etc/inittab file.

     # Run xdm in runlevel 5
     # xdm is now a separate service
     x:5:respawn:/etc/X11/prefdm -nodaemon 

Once I comment out the last line and save my changes, I am
almost ready. Assuming you are using a graphical login, you could,
at this time, reboot your system and the new changes would take
effect. You would boot up into a beautiful, text-only console
screen. Ah, simplicity. I could also tell you that in order for the
changes to take effect, you could just get
init to re-read the
/etc/inittab file. You do that like this
(but don't do it yet).

     init q

If you happen to be running a Debian system, (or Storm or
Corel), your graphical login manager may be started from one of the
rc files. Those are the ones you find under
/etc/init.d. In that case, you can terminate the
login manager in this manner. Be careful though--if you do it while
you are in the session, then your graphical manager session will
terminate, X will close and you may lose any work you had open. All
that to say you should now save your work, close any applications
you had running and log out of the desktop.

     /etc/init.d/kdm stop

This brings up another problem. How do you get to a shell
prompt to run init q without being logged into
your desktop?You can, without affecting your current X window session,
jump out of that session by hitting
Ctrl-Alt-F1. Function key 1 could
just as easily be 2, 3, 4, 5 or 6. If you started X from the
command line with X, you'll probably see the dialog for the session
when you click on Ctrl-Alt-F1. The F2, F3 (and so on) versions
should provide you with a text-based login screen. By the way, in
case you did not already know this, you can switch from any of
these "virtual" terminals (VTs) to another
simply by typing Alt-F# (where "#"
is the number). To get back to your X window session, you click
Ctrl-Alt-F7. Go ahead and try it. Flip back and forth. When you are
feeling comfy with this, head on back to a text screen
(Ctrl-Alt-F1).Now that you have a text screen, we'll move on to some fun
things. By the way, if you were among those running X from the
graphical login manager, now is the time to cancel it, either with
init q or through the appropriate
rc script. All right. Back to those virtual
terminals. So, function keys 1 through 6 represent your virtual
terminal numbers while function key 7 is your first X session. What
about 8, 9, and 10?Well, let's try something fun.The reason our first X terminal is usually at six is because
virtual terminals one through six are spoken for in our default
/etc/inittab file. Here's the relevant section
from my /etc/inittab:

     # Run gettys in standard runlevels
     1:2345:respawn:/sbin/mingetty tty1
     2:2345:respawn:/sbin/mingetty tty2
     3:2345:respawn:/sbin/mingetty tty3
     4:2345:respawn:/sbin/mingetty tty4
     5:2345:respawn:/sbin/mingetty tty5
     6:2345:respawn:/sbin/mingetty tty6

What do you think would be affected if you were to log in as
root, take your favorite editor (vi, Emacs, pico, nano) and comment
out the last line? Give it a try. Like the previous change to the
inittab, you still need to get
init to re-read the
/etc/inittab file.Now, switch to virtual terminal number six. Suddenly, this is
no longer a usable terminal. There is no login prompt. Cool? Well,
maybe not, but try this now. Start your X session with this simple
command. You might just remember this from the
last column:

     xinit /usr/X11R6/bin/xterm

This gives you a really boring, plain X screen with a single
X terminal up in the top left hand corner. You have no way to move
it and nothing to be done. Today, we're going to use it to
demonstrate something. While you are in that screen, flip back over
to your first virtual terminal (Ctrl-Alt-F1). Great. Now, from the
text console, go back into your X session by hitting Ctrl-Alt-F7.
Was something wrong? Try Ctrl-Alt-F6 instead.
Aha!
What happened here is that
startx (or
xinit) in this case started X on
the first available free VT which is now
number six (because we turned off the getty on VT 6. Here comes
cool trick number two. Leave your boring X session running, and go
back to the text console. Now, so that we don't confuse one boring
xterm session with another, type this command:

     xinit /usr/X11R6/bin/xcalc -- :1

If you switch back to your text console now, you'll notice
some interesting things if you try to revisit your X session.
Ctrl-Alt-F6 (assuming you still have VT 6 commented out of the
inittab) will take you to your xterm. To get to your
xcalc session, type Ctrl-Alt-F7.
Since you can't type exit at the command prompt of xterm, you need
to use the X window escape hatch to close that session. The
"oh, my God, I've tried everything and I can't get out of
X" escape clause is this --
Ctrl-Alt-Backspace.Here's something else that you might find interesting. You
can also define which virtual terminal you
want X to start on. Say that ten is your lucky number and you like
your X session to start on VT 10.

     startx -- :1 vt10

I said that I would get back to some of these ".X" files, and
this time around I want to talk about your .Xresources file. By
now, you may have already started to get the idea that your desktop
is an amazingly configurable environment. While the window manager
does some things, you can exert further control still. For
instance: If I start an xterm session, I get a nice flashing blue
cursor. Let's say I wanted that cursor to be red or blue. I would
change that either by creating or modifying my
.Xresources file.Before we get into the nitty-gritty of the file structure,
you should know that you already have a global file that handles
all of this for you. Actually, you have several. Change directory
to /usr/X11R6/lib/X11/app-defaults, and you will
find a number of files that pre-define some of the standard X
applications. In your home directory, you may also find a
.Xdefaults file that does more or less the same
thing. Mine has some defaults set up for several applications
including Emacs, rxvt and xterm.Back to my xterm. What changes do I need to make? Well, if I
check out the man page for xterm with man xterm
and look for the X resources, I find that
cursorColor is the attribute that affects the
color of the cursor. If I exit my .Xdefaults or
.Xresources file and add those changes, I get
this. Oh, and I've changed my mind. I would rather have my cursor
as a hard-to-read wheat color:

     XTerm*cursorColor:      Wheat

Notice that I preface the resource with
XTerm* to tell my X resource file what this
resource belongs to (or affects). Since I want these changes to
take place without logging out of my X session and logging back in,
I need to have the system re-read my configuration and incorporate
the changes. This is how I do it:

     xrdb -merge $HOME/.Xdefaults

xrdb, by the way, is the X
resource database utility. This program usually gets run somewhere
along the way when you start an X session. On my system, it is
called by /etc/X11/xinit/xinitrc. If I had
created a .Xresources file instead, then my
command would have been as follows:

     xrdb -merge $HOME/.Xresources

I start a new xterm and behold, the cursor is a wheat color.
Let's try a more interesting example. For instance, when I start
Netscape, I get a menubar with the word "Help" over on the right. I
also get the word "Location" beside my URL address bar. Let's just
say, for fun, that when I need help, it's more like an S.O.S. than
a simple request for help. I'd like my browser to say S.O.S. for
help and URL for my location bar. This is how I tackle this one. At
the end of my .Xdefaults or
.Xresources file, I add the following
lines.

     Netscape*menuBar.helpMenu.labelString:          S.O.S.
     Netscape*urlLocationLabel.uneditedLabelString:          URL: 

Before we continue, we need to re-run xrdb to merge those
resources. Now, if I close my browser and restart it, I get things
displayed the way I want them to be. By the way, I found the X
resource or Netscape in the accompanying documentation distributed
with the browser. On my machine, (and with Netscape 4.75) this
documentation lives at
/usr/doc/netscape-common-4.75/Netscape.ad
.Whoa! I've been going on for far too long. It's extremely
easy to get caught up in all of this. The X Window System is so
incredibly flexible that playing around with it can be quite
addictive. Until next time, take care everyone, and remember that a
little gratuitous window dressing never hurt anyone. X needs no
warning labels.

email: ljeditors@ssc.com