Linux.Desktop.Hacks [Electronic resources] نسخه متنی

Hack 20. Scrap X11 for Fancy Login Consoles

Qingy is an attractive replacement for X
Windows-based graphical login managers such as XDM, GDM, and KDM.

Qingy is an alternative login screen developed by Michele Noberasco
(http://qingy.sourceforge.net/news.php). Qingy
uses the graphical frame-buffer console capability in Linux to paint
an attractive and powerful session login screen on one or more
virtual terminals. Unlike XDM, GDM, and KDM, Qingy does not use X11.
Despite this, Qingy has as many features as these traditional
graphical login screens, if not more (see the sidebar, Frame-Buffer Versus X11 Graphics). You can choose your
preferred session type, such as KDE, GNOME, WindowMaker, Fluxbox, or
just a text console. You can include buttons on the Qingy login
screen that will start the screensaver, put your computer in sleep
mode, reboot, shut down, and many other options. And of course, you
can change the Qingy graphical theme.

Qingy stands for "Qingy Is Not
GettY." getty is the text-based
terminal program that greets you with a login prompt. You have
several of these text-based virtual consoles (terminals) on your
machine, and you can switch between them by pressing Ctrl-Alt-F1,
Ctrl-Alt-F2, Ctrl-Alt-F3, and so on. (You can omit the Ctrl key if
you're not switching to a text console from a
graphical desktop.) Each desktop is a virtual terminal that uses a
version of getty as a terminal emulator. Various
Linux distributions use alternatives, such as
agetty, mingetty, and
others; despite a few feature differences, they all amount to the
same thinga text-based terminal console.

Qingy replaces getty with
an
attractive graphical login screen that can automatically launch any
one of your favorite graphical desktops or a text console. You can
start Qingy on more than one virtual console, which means two or more
people can use Qingy to log in and start their own desktops. Qingy
also has some built-in security. You can configure Qingy to make it
impossible for another user to get to your desktop without knowing
your password.

A number of themes are available for Qingy. Figure 3-1 is based on the theme called
"biohazard."

Figure 3-1. Qingy login screen

3.6.1. Prepare to Install Qingy

It is not difficult to install Qingy. First,
you
must have frame-buffer support and frame-buffer console support
compiled into your Linux kernel (you do not need boot splash support
compiled into the kernel, however).
[Hack #8] and [Hack #9] include instructions for
compiling frame-buffer support and frame-buffer console support into
the kernel. Once you have modified your kernel, reboot so that these
changes will take effect.

If your system automatically launches a graphical login manager, such
as GDM, KDM, or XDM, the first thing you want to do is disable it.
You won't need to use it anymore after you have
Qingy working.

You can turn off these login managers in several ways. This command
is one way you can do it on a Debian system:

# update-rc.d -f kdm remove
Removing any system startup links for /etc/init.d/kdm ...
/etc/rc0.d/K01kdm
/etc/rc3.d/S99kdm
/etc/rc4.d/S99kdm
/etc/rc6.d/K01kdm

On Gentoo, the command should be as follows:

# rc-update del xdm default

A generic approach also exists that should work with almost every
Linux distribution (it doesn't work for Fedora).

First, check to see what the default run level is for your system.
You can do this by examining the file
/etc/inittab. Look for a line that reads like
this:

id:3:initdefault:

This tells you the default run level is 3. For most Linux systems,
this means you want to log in as root and change to the directory
/etc/rc3.d. If the default run level turned out
to be 5, you would change to the directory
/etc/rc5.d. Then look for any symbolic links to
kdm, gdm, or
xdm and delete them. For example:

# cd /etc/rc3.d
# ls -l *dm
lrwxrwxrwx  1 root root 17 Nov 17  2003 S99xdm -> ../init.d/xdm
# rm S99xdm

3.6.2. Install Qingy

If your Linux distribution
has
a Qingy package, install it via your package manager. If you can
install Qingy from a package manager, it will likely place
configuration files in the /etc/qingy directory,
place theme files in /usr/share/qingy/themes,
and install the qingy program in
/sbin.

If you download the source code and compile it yourself, it will store configuration files (by default) in /usr/local/etc/qingy, store theme files in /usr/local/share/qingy/themes, and place the executable qingy in /usr/local/sbin. Consider these differences when viewing the following examples, which assume that you compiled Qingy for yourself.

If you do not have a Qingy package for your Linux distribution, you
have to download and compile the code yourself. Download the latest
version of Qingy from http://qingy.sourceforge.net/news.php. Log in
as root, and change to an appropriate directory (such as
/usr/local/src). Extract the code, change to the
source directory, configure, compile, and install the program.
(Consider that by the time you read this, a more recent version of
Qingy might be availableuse that version instead of 0.5.2.)
Here is an example of how to perform the preceding steps:

$ su -
# cp qingy-0.5.2.tar.bz2 /usr/local/src
# cd /usr/local/src
# tar jxvf qingy-0.5.2.tar.bz2
# cd qingy-0.5.2
# ./configure
# make
# make install

You can specify an alternate prefix when you run
./configure. The prefix tells the build
session where to install the files. For example, if you want Qingy to
install in /usr/sbin, you would type:

# ./configure --prefix=/usr

The default setting will install the qingy
program in /usr/local/sbin, and store the
settings file in
/usr/local/etc/. This installs the default theme
to /usr/local/share/qingy/themes.

3.6.3. Configure Linux to Use Qingy

If you took the preceding advice,
you
have already compiled and are running a Linux kernel that supports
frame-buffer consoles. This means you can see the immediate results
of any changes to your console settings.

To avoid any potential complications, make all of these changes from
a virtual console that is not going to be configured for Qingy. For
this example, only the first two virtual consoles will be configured
as Qingy login screens. If you are logged in to virtual console 1 or
2, press Ctrl-Alt-F1 and log out of the first virtual console, then
press Ctrl-Alt-F2 and log out of the second virtual console. If you
don't log out of these consoles, the changes you
make will not take effect immediately. Then press Ctrl-Alt-F3 to go
to the third virtual terminal (which will not run Qingy), and log in
as root there.

Now use your favorite editor to edit your
/etc/inittab file. Find the section that looks
something like this:

# TERMINALS
c1:12345:respawn:/sbin/agetty 38400 tty1 linux
c2:12345:respawn:/sbin/agetty 38400 tty2 linux
c3:12345:respawn:/sbin/agetty 38400 tty3 linux
c4:12345:respawn:/sbin/agetty 38400 tty4 linux
c5:12345:respawn:/sbin/agetty 38400 tty5 linux
c6:12345:respawn:/sbin/agetty 38400 tty6 linux

You need to change one or more lines to spawn
qingy instead of the agetty
terminal program. (Your Linux distribution might use something other
than agetty, such as getty
or mingetty. This doesn't
matter.) It isn't necessary or even desirable to
change every virtual terminal to use Qingy. If something goes wrong,
you want at least one terminal to behave normally so that you can log
in and diagnose the problem. In this example, change just the first
two virtual terminals to use Qingy. Edit the
/etc/inittab file to look more like this:

# TERMINALS
c1:12345:respawn:/usr/local/sbin/qingy tty1 --screensaver 0
c2:12345:respawn:/usr/local/sbin/qingy tty2 --screensaver 0
c3:12345:respawn:/sbin/agetty 38400 tty3 linux
c4:12345:respawn:/sbin/agetty 38400 tty4 linux
c5:12345:respawn:/sbin/agetty 38400 tty5 linux
c6:12345:respawn:/sbin/agetty 38400 tty6 linux

Obviously, if you installed Qingy from a package that placed the
qingy executable in the
/sbin directory modify the absolute path to
Qingy appropriately. The --screensaver 0 switch at
the end of the line turns off the Qingy screensaver. The screensaver
is sometimes triggered after a few minutes even if
you're actively typing on a non-Qingy console, which
can be annoying. Qingy is young yet. Perhaps this quirk will be fixed
in a future version.

Save the /etc/inittab file. Now execute the
following commands:

# init Q
# killall agetty

The first command tells Linux to reexamine the
/etc/inittab file. It does not automatically
turn off the agetty sessions for any of the
virtual consoles, though. That is why you need the second command.
This kills every version of agetty that might be
running except the one you are currently using. Instead of respawning
(restarting) agetty in virtual consoles 1 and 2,
Linux will respawn qingy.

If your version of Linux uses something other than
/sbin/agetty for normal terminal sessions,
substitute the name of your version of agetty in
the killall command. For example, if your
Linux distribution uses getty, issue these
commands instead:

# init Q
# killall getty

Press Ctrl-Alt-F1 and now you should see the Qingy login screen. Use
the Tab key or your mouse to move from one input field to another.
When you select the session field, you can change the session setting
by pressing the up and down arrows. Select whichever window manager
you prefer or the text console. Once you have typed in your username
and password and you've selected your desired
session, press Enter. You should see your selected session start up.
If you start up a window manager or desktop environment, such as KDE
or GNOME, Qingy has to start X11 from scratch. Therefore, you might
notice it takes a bit longer to start up than if you were running the
KDE or GNOME login manager, which load faster because X11 was already
running.

If someone else wants to use the computer and you
don't want to close your session, press Ctrl-Alt-F2
to get to the second Qingy login screen. Allow the other user to log
in and start her separate session.

You can switch between sessions by pressing Ctrl-Alt-F1 and
Ctrl-Alt-F2. Virtual consoles are still available on Ctrl-Alt-F3
through F6.

3.6.4. When Qingy Doesn't Offer Session Choices

One common occurrence is
that Qingy doesn't
display any window managers or desktop environments in its session
field. By default, Qingy looks in the
/etc/X11/Sessions directory for a list of files,
each representing a window manager or desktop available on your
system. The name of the file appears in the Qingy sessions list.
These session files contain a single line, a full path to the
executable to the window manager or desktop. For example, the file
named /etc/X11/Sessions/KDE might contain the
line /usr/bin/startkde, and the file
/etc/X11/Sessions/WindowMaker should contain a
single line such as /usr/bin/wmaker.

If you don't see any window managers available from
the Qingy login screen, you have one of two problems. Your session
files are stored somewhere other than
/etc/X11/Sessions or your system simply
doesn't work that waythere is no single
directory of session files.

If your system stores the session files somewhere other than
/etc/X11/Sessions, edit the Qingy configuration
file /usr/local/etc/qingy/settings so that it
points to the directory where your system keeps its session files.
Locate the following line:

x_sessions = "/etc/X11/Sessions/"

and change it to the absolute path to your
Sessions directory.

If your system doesn't have a
Sessions directory, here's an
easy way to create one and fill it with session files for each window
manager and desktop you have installed. Before you create each
session file, check to see if the window manager executable (the file
that actually starts up the window manager) exists. If the
which command reports back a path to the file
you're looking for, create the session file by
redirecting the output of the which command to a
session file. If the output can't find the
executable for a window manager (the following example shows that
blackbox is not available),
don't create a session file for it. Table 3-1, earlier in this chapter, lists the common
window manager executable filenames.

You can name the session file anything, so pick a name that is
meaningful to you. For example, the WindowMaker executable is
/usr/bin/wmaker, but you can use
"wmaker" or
"WindowMaker" if you like. The
following example shows how to use the which
command and command redirection to create your session files:

# mkdir /etc/X11/Sessions
# which wmaker /usr/bin/wmaker
# which wmaker > /etc/X11/Sessions/WindowMaker
# which twm /usr/X11R6/bin/twm
# which twm > /etc/X11/Sessions/TabWM
# which blackbox which: no blackbox in (/usr/bin:/usr/local/bin:/etc...)
# which fluxbox /usr/bin/fluxbox
# which fluxbox > /etc/X11/Sessions/Fluxbox
# which startkde /usr/bin/startkde
# which startkde > /etc/X11/Sessions/KDE
# which gnome-session /usr/bin/gnome-session
# which gnome-session > /etc/X11/Sessions/GNOME

These sessions should appear automatically on your Qingy login screen
as you create each session file. There is no need to restart
anything.