Provided by:
xscreensaver_4.24-5ubuntu3_i386 
NAME
xscreensaver - extensible screen saver framework, plus locking
SYNOPSIS
xscreensaver [-display host:display.screen] [-verbose] [-no-cap‐
ture-stderr] [-no-splash]
DESCRIPTION
The xscreensaver program waits until the keyboard and mouse have been
idle for a period, and then runs a graphics demo chosen at random. It
turns off as soon as there is any mouse or keyboard activity.
This program can lock your terminal in order to prevent others from
using it, though its default mode of operation is merely to display
pretty pictures on your screen when it is not in use.
It also provides configuration and control of your monitor’s power-sav‐
ing features.
For the impatient, try this:
xscreensaver &
xscreensaver-demo
The xscreensaver-demo(1) program pops up a dialog box that lets you
configure the screen saver, and experiment with the various display
modes.
Note: unlike xlock(1), xscreensaver has a client-server model: the
xscreensaver program is a daemon that runs in the background; it is
controlled by the foreground xscreensaver-demo(1) and xscreensaver-com
mand(1) programs.
CONFIGURATION
The easiest way to configure xscreensaver is to simply run the xscreen
saver-demo(1) program, and change the settings through the GUI. The
rest of this manual page describes lower level ways of changing set‐
tings.
I’ll repeat that because it’s important:
The easy way to configure xscreensaver is to run the xscreensaver-
demo(1) program. You shouldn’t need to know any of the stuff
described in this manual unless you are trying to do something
tricky, like customize xscreensaver for site-wide use or something.
Options to xscreensaver are stored in one of two places: in a .xscreen‐
saver file in your home directory; or in the X resource database. If
the .xscreensaver file exists, it overrides any settings in the
resource database.
The syntax of the .xscreensaver file is similar to that of the .Xde‐
faults file; for example, to set the timeout paramter in the .xscreen‐
saver file, you would write the following:
timeout: 5
whereas, in the .Xdefaults file, you would write
xscreensaver.timeout: 5
If you change a setting in the .xscreensaver file while xscreensaver is
already running, it will notice this, and reload the file. (The file
will be reloaded the next time the screen saver needs to take some
action, such as blanking or unblanking the screen, or picking a new
graphics mode.)
If you change a setting in your X resource database, or if you want
xscreensaver to notice your changes immediately instead of the next
time it wakes up, then you will need to reload your .Xdefaults file,
and then tell the running xscreensaver process to restart itself, like
so:
xrdb < ~/.Xdefaults
xscreensaver-command -restart
If you want to set the system-wide defaults, then make your edits to
the xscreensaver app-defaults file, which should have been installed
when xscreensaver itself was installed. The app-defaults file will
usually be named /usr/lib/X11/app-defaults/XScreenSaver, but different
systems might keep it in a different place (for example, /usr/open‐
win/lib/app-defaults/XScreenSaver on Solaris.)
When settings are changed in the Preferences dialog box (see above) the
current settings will be written to the .xscreensaver file. (The .Xde‐
faults file and the app-defaults file will never be written by xscreen‐
saver itself.)
timeout (class Time)
The screensaver will activate (blank the screen) after the key‐
board and mouse have been idle for this many minutes. Default
10 minutes.
cycle (class Time)
After the screensaver has been running for this many minutes,
the currently running graphics-hack sub-process will be killed
(with SIGTERM), and a new one started. If this is 0, then the
graphics hack will never be changed: only one demo will run
until the screensaver is deactivated by user activity. Default
10 minutes.
lock (class Boolean)
Enable locking: before the screensaver will turn off, it will
require you to type the password of the logged-in user (really,
the person who ran xscreensaver), or the root password. (Note:
this doesn’t work if the screensaver is launched by xdm(1)
because it can’t know the user-id of the logged-in user. See
the ‘‘Using XDM(1)’’ section, below.
lockTimeout (class Time)
If locking is enabled, this controls the length of the ‘‘grace
period’’ between when the screensaver activates, and when the
screen becomes locked. For example, if this is 5, and -timeout
is 10, then after 10 minutes, the screen would blank. If there
was user activity at 12 minutes, no password would be required
to un-blank the screen. But, if there was user activity at 15
minutes or later (that is, -lock-timeout minutes after activa‐
tion) then a password would be required. The default is 0,
meaning that if locking is enabled, then a password will be
required as soon as the screen blanks.
passwdTimeout (class Time)
If the screen is locked, then this is how many seconds the
password dialog box should be left on the screen before giving
up (default 30 seconds.) This should not be too large: the X
server is grabbed for the duration that the password dialog box
is up (for security purposes) and leaving the server grabbed
for too long can cause problems.
dpmsEnabled (class Boolean)
Whether power management is enabled.
dpmsStandby (class Time)
If power management is enabled, how long until the monitor goes
solid black.
dpmsSuspend (class Time)
If power management is enabled, how long until the monitor goes
into power-saving mode.
dpmsOff (class Time)
If power management is enabled, how long until the monitor pow‐
ers down completely. Note that these settings will have no
effect unless both the X server and the display hardware sup‐
port power management; not all do. See the Power Management
section, below, for more information.
visualID (class VisualID)
Specify which X visual to use by default. (Note carefully that
this resource is called visualID, not merely visual; if you set
the visual resource instead, things will malfunction in obscure
ways for obscure reasons.)
Legal values for the VisualID resource are:
default Use the screen’s default visual (the visual of the root
window.) This is the default.
best Use the visual which supports the most colors. Note,
however, that the visual with the most colors might be
a TrueColor visual, which does not support colormap
animation. Some programs have more interesting behav‐
ior when run on PseudoColor visuals than on TrueColor.
mono Use a monochrome visual, if there is one.
gray Use a grayscale or staticgray visual, if there is one
and it has more than one plane (that is, it’s not
monochrome.)
color Use the best of the color visuals, if there are any.
GL Use the visual that is best for OpenGL programs.
(OpenGL programs have somewhat different requirements
than other X programs.)
class where class is one of StaticGray, StaticColor, True
Color, GrayScale, PseudoColor, or DirectColor. Selects
the deepest visual of the given class.
number where number (decimal or hex) is interpreted as a
visual id number, as reported by the xdpyinfo(1) pro‐
gram; in this way you can have finer control over
exactly which visual gets used, for example, to select
a shallower one than would otherwise have been chosen.
Note that this option specifies only the default visual that
will be used: the visual used may be overridden on a program-
by-program basis. See the description of the programs
resource, below.
installColormap (class Boolean)
On PseudoColor (8-bit) displays, install a private colormap
while the screensaver is active, so that the graphics hacks can
get as many colors as possible. This is the default. (This
only applies when the screen’s default visual is being used,
since non-default visuals get their own colormaps automati‐
cally.) This can also be overridden on a per-hack basis: see
the discussion of the default-n name in the section about the
programs resource.
This does nothing if you have a TrueColor (16-bit or deeper)
display.
verbose (class Boolean)
Whether to print diagnostics. Default false.
timestamp (class Boolean)
Whether to print the time of day along with any other diagnos‐
tic messages. Default true.
splash (class Boolean)
Whether to display a splash screen at startup. Default true.
splashDuration (class Time)
How long the splash screen should remain visible; default 5
seconds.
quad (class Boolean)
If true, then four screensavers will be run on each monitor.
Use at your own risk!
helpURL (class URL)
The splash screen has a Help button on it. When you press it,
it will display the web page indicated here in your web
browser.
loadURL (class LoadURL)
This is the shell command used to load a URL into your web
browser. The default setting will load it into
Mozilla/Netscape if it is already running, otherwise, will
launch a new browser looking at the helpURL.
demoCommand (class DemoCommand)
This is the shell command run when the Demo button on the
splash window is pressed. It defaults to xscreensaver-demo(1).
prefsCommand (class PrefsCommand)
This is the shell command run when the Prefs button on the
splash window is pressed. It defaults to xscreen‐
saver-demo -prefs.
nice (class Nice)
The sub-processes created by xscreensaver will be ‘‘niced’’ to
this level, so that they are given lower priority than other
processes on the system, and don’t increase the load unneces‐
sarily. The default is 10.
(Higher numbers mean lower priority; see nice(1) for details.)
fade (class Boolean)
If this is true, then when the screensaver activates, the cur‐
rent contents of the screen will fade to black instead of sim‐
ply winking out. This only works on certain systems. A fade
will also be done when switching graphics hacks (when the cycle
timer expires.) Default: true.
unfade (class Boolean)
If this is true, then when the screensaver deactivates, the
original contents of the screen will fade in from black instead
of appearing immediately. This only works on certain systems,
and if fade is true as well. Default false.
fadeSeconds (class Time)
If fade is true, this is how long the fade will be in seconds
(default 3 seconds.)
fadeTicks (class Integer)
If fade is true, this is how many times a second the colormap
will be changed to effect a fade. Higher numbers yield
smoother fades, but may make the fades take longer than the
specified fadeSeconds if your server isn’t fast enough to keep
up. Default 20.
captureStderr (class Boolean)
Whether xscreensaver should redirect its stdout and stderr
streams to the window itself. Since its nature is to take over
the screen, you would not normally see error messages generated
by xscreensaver or the sub-programs it runs; this resource will
cause the output of all relevant programs to be drawn on the
screensaver window itself, as well as being written to the con‐
trolling terminal of the screensaver driver process. Default
true.
ignoreUninstalledPrograms (class Boolean)
There may be programs in the list that are not installed on the
system, yet are marked as "enabled." If this preference is
true, then such programs will simply be ignored. If false,
then a warning will be printed if an attempt is made to run the
nonexistent program. Also, the xscreensaver-demo(1) program
will suppress the non-existent programs from the list if this
is true. Default: false.
GetViewPortIsFullOfLies (class Boolean)
Set this to true if the xscreensaver window doesn’t cover the
whole screen. This works around a longstanding XFree86 bug
#421. See the xscreensaver FAQ for details.
font (class Font)
The font used for the stdout/stderr text, if captureStderr is
true. Default *-medium-r-*-140-*-m-* (a 14 point fixed-width
font.)
mode (class Mode)
Controls the behavior of xscreensaver. Legal values are:
random When blanking the screen, select a random display mode
from among those that are enabled and applicable. This
is the default.
random-same
Like random, but if there are multiple screens, each
screen will run the same random display mode, instead
of each screen running a different one.
one When blanking the screen, only ever use one particular
display mode (the one indicated by the selected set‐
ting.)
blank When blanking the screen, just go black: don’t run any
graphics hacks.
off Don’t ever blank the screen, and don’t ever allow the
monitor to power down.
selected (class Integer)
When mode is set to one, this is the one, indicated by its
index in the programs list. You’re crazy if you count them and
set this number by hand: let xscreensaver-demo(1) do it for
you!
programs (class Programs)
The graphics hacks which xscreensaver runs when the user is
idle. The value of this resource is a multi-line string, one
sh-syntax command per line. Each line must contain exactly one
command: no semicolons, no ampersands.
When the screensaver starts up, one of these is selected
(according to the mode setting), and run. After the cycle
period expires, it is killed, and another is selected and run.
If a line begins with a dash (-) then that particular program
is disabled: it won’t be selected at random (though you can
still select it explicitly using the xscreensaver-demo(1) pro‐
gram.)
If all programs are disabled, then the screen will just be made
blank, as when mode is set to blank.
To disable a program, you must mark it as disabled with a dash
instead of removing it from the list. This is because the sys‐
tem-wide (app-defaults) and per-user (.xscreensaver) settings
are merged together, and if a user just deletes an entry from
their programs list, but that entry still exists in the system-
wide list, then it will come back. However, if the user dis‐
ables it, then their setting takes precedence.
If the display has multiple screens, then a different program
will be run for each screen. (All screens are blanked and
unblanked simultaneously.)
Note that you must escape the newlines; here is an example of
how you might set this in your ~/.xscreensaver file:
programs: \
qix -root \n\
ico -r -faces -sleep 1 -obj ico \n\
xdaliclock -builtin2 -root \n\
xv -root -rmode 5 image.gif -quit \n
Make sure your $PATH environment variable is set up correctly
before xscreensaver is launched, or it won’t be able to find
the programs listed in the programs resource.
To use a program as a screensaver, two things are required:
that that program draw on the root window (or be able to be
configured to draw on the root window); and that that program
understand ‘‘virtual root’’ windows, as used by virtual window
managers such as tvtwm(1). (Generally, this is accomplished by
just including the "vroot.h" header file in the program’s
source.)
If there are some programs that you want to run only when using
a color display, and others that you want to run only when
using a monochrome display, you can specify that like this:
mono: mono-program -root \n\
color: color-program -root \n\
More generally, you can specify the kind of visual that should
be used for the window on which the program will be drawing.
For example, if one program works best if it has a colormap,
but another works best if it has a 24-bit visual, both can be
accommodated:
PseudoColor: cmap-program -root \n\
TrueColor: 24bit-program -root \n\
In addition to the symbolic visual names described above (in
the discussion of the visualID resource) one other visual name
is supported in the programs list:
default-n
This is like default, but also requests the use of the
default colormap, instead of a private colormap. (That
is, it behaves as if the -no-install command-line option
was specified, but only for this particular hack.) This
is provided because some third-party programs that draw on
the root window (notably: xv(1), and xearth(1)) make
assumptions about the visual and colormap of the root win‐
dow: assumptions which xscreensaver can violate.
If you specify a particular visual for a program, and that
visual does not exist on the screen, then that program will not
be chosen to run. This means that on displays with multiple
screens of different depths, you can arrange for appropriate
hacks to be run on each. For example, if one screen is color
and the other is monochrome, hacks that look good in mono can
be run on one, and hacks that only look good in color will show
up on the other.
You shouldn’t ever need to change the following resources:
pointerPollTime (class Time)
When server extensions are not in use, this controls how fre‐
quently xscreensaver checks to see if the mouse position or
buttons have changed. Default 5 seconds.
pointerHysteresis (class Integer)
If the mouse moves less than this-many pixels in a second,
ignore it (do not consider that to be "activity.") This is so
that the screen doesn’t un-blank (or fail to blank) just
because you bumped the desk. Default: 10 pixels.
windowCreationTimeout (class Time)
When server extensions are not in use, this controls the delay
between when windows are created and when xscreensaver selects
events on them. Default 30 seconds.
initialDelay (class Time)
When server extensions are not in use, xscreensaver will wait
this many seconds before selecting events on existing windows,
under the assumption that xscreensaver is started during your
login procedure, and the window state may be in flux. Default
0. (This used to default to 30, but that was back in the days
when slow machines and X terminals were more common...)
There are a number of different X server extensions which can make
xscreensaver’s job easier. The next few resources specify whether
these extensions should be utilized if they are available.
sgiSaverExtension (class Boolean)
This resource controls whether the SGI SCREEN_SAVER server
extension will be used to decide whether the user is idle.
This is the default if xscreensaver has been compiled with sup‐
port for this extension (which is the default on SGI systems.).
If it is available, the SCREEN_SAVER method is faster and more
reliable than what will be done otherwise, so use it if you
can. (This extension is only available on Silicon Graphics
systems, unfortunately.)
mitSaverExtension (class Boolean)
This resource controls whether the MIT-SCREEN-SAVER server
extension will be used to decide whether the user is idle.
However, the default for this resource is false, because even
if this extension is available, it is flaky (and it also makes
the fade option not work properly.) Use of this extension is
strongly discouraged. Support for it will probably be removed
eventually.
xidleExtension (class Boolean)
This resource controls whether the XIDLE server extension will
be used to decide whether the user is idle. This is the
default if xscreensaver has been compiled with support for this
extension. (This extension is only available for X11R4 and
X11R5 systems, unfortunately.)
procInterrupts (class Boolean)
This resource controls whether the /proc/interrupts file should
be consulted to decide whether the user is idle. This is the
default if xscreensaver has been compiled on a system which
supports this mechanism (i.e., Linux systems.)
The benefit to doing this is that xscreensaver can note that
the user is active even when the X console is not the active
one: if the user is typing in another virtual console, xscreen‐
saver will notice that and will fail to activate. For example,
if you’re playing Quake in VGA-mode, xscreensaver won’t wake up
in the middle of your game and start competing for CPU.
The drawback to doing this is that perhaps you really do want
idleness on the X console to cause the X display to lock, even
if there is activity on other virtual consoles. If you want
that, then set this option to False. (Or just lock the X con‐
sole manually.)
The default value for this resource is True, on systems where
it works.
overlayStderr (class Boolean)
If captureStderr is True, and your server supports ‘‘overlay’’
visuals, then the text will be written into one of the higher
layers instead of into the same layer as the running screen‐
hack. Set this to False to disable that (though you shouldn’t
need to.)
overlayTextForeground (class Foreground)
The foreground color used for the stdout/stderr text, if cap
tureStderr is true. Default: Yellow.
overlayTextBackground (class Background)
The background color used for the stdout/stderr text, if cap
tureStderr is true. Default: Black.
bourneShell (class BourneShell)
The pathname of the shell that xscreensaver uses to start sub‐
processes. This must be whatever your local variant of /bin/sh
is: in particular, it must not be csh.
xscreensaver also accepts a few command-line options, mostly for use
when debugging: for normal operation, you should configure things via
the ~/.xscreensaver file.
-display host:display.screen
The X display to use. For displays with multiple screens,
XScreenSaver will manage all screens on the display simultan‐
iously.
-verbose
Same as setting the verbose resource to true: print diagnostics
on stderr and on the xscreensaver window.
-no-capture-stderr
Same as setting the captureStderr resource to false: do not
redirect the stdout and stderr streams to the xscreensaver
window itself. If xscreensaver is crashing, you might need to
do this in order to see the error message.
When it is time to activate the screensaver, a full-screen black window
is created on each screen of the display. Each window is created in
such a way that, to any subsequently-created programs, it will appear
to be a ‘‘virtual root’’ window. Because of this, any program which
draws on the root window (and which understands virtual roots) can be
used as a screensaver.
When the user becomes active again, the screensaver windows are
unmapped, and the running subprocesses are killed by sending them
SIGTERM. This is also how the subprocesses are killed when the screen‐
saver decides that it’s time to run a different demo: the old one is
killed and a new one is launched.
Before launching a subprocess, xscreensaver stores an appropriate value
for $DISPLAY in the environment that the child will receive. (This is
so that if you start xscreensaver with a -display argument, the pro‐
grams which xscreensaver launches will draw on the same display; and so
that the child will end up drawing on the appropriate screen of a
multi-headed display.)
When the screensaver turns off, or is killed, care is taken to restore
the ‘‘real’’ virtual root window if there is one. Because of this, it
is important that you not kill the screensaver process with kill -9 if
you are running a virtual-root window manager. If you kill it with -9,
you may need to restart your window manager to repair the damage. This
isn’t an issue if you aren’t running a virtual-root window manager.
For all the gory details, see the commentary at the top of xscreen‐
saver.c.
You can control a running screensaver process by using the xscreen
saver-command(1) program (which see.)
Modern X servers contain support to power down the monitor after an
idle period. If the monitor has powered down, then xscreensaver will
notice this (after a few minutes), and will not waste CPU by drawing
graphics demos on a black screen. An attempt will also be made to
explicitly power the monitor back up as soon as user activity is
detected.
As of version 3.28 (Feb 2001), the ~/.xscreensaver file controls the
configuration of your display’s power management settings: if you have
used xset(1) to change your power management settings, then xscreen‐
saver will override those changes with the values specified in
~/.xscreensaver (or with its built-in defaults, if there is no
~/.xscreensaver file yet.)
To change your power management settings, run xscreensaver-demo(1) and
change the various timeouts through the user interface. Alternately,
you can edit the ~/.xscreensaver file directly.
If the power management section is grayed out in the xscreen
saver-demo(1) window, then that means that your X server does not sup‐
port the XDPMS extension, and so control over the monitor’s power state
is not available.
If you’re using a laptop, don’t be surprised if changing the DPMS set‐
tings has no effect: many laptops have monitor power-saving behavior
built in at a very low level that is invisible to Unix and X. On such
systems, you can typically adjust the power-saving delays only by
changing settings in the BIOS in some hardware-specific way.
If DPMS seems not to be working with XFree86, make sure the "DPMS"
option is set in your /etc/X11/XF86Config file. See the XF86Config(5)
manual for details.
You can run xscreensaver from your xdm(1) session, so that the screen‐
saver will run even when nobody is logged in on the console.
The trick to using xscreensaver with xdm is this: keep in mind the two
very different states in which xscreensaver will be running:
1: Nobody logged in.
If you’re thinking of running xscreensaver from XDM at all, then
it’s probably because you want graphics demos to be running on
the console when nobody is logged in there. In this case,
xscreensaver will function only as a screen saver, not a screen
locker: it doesn’t make sense for xscreensaver to lock the
screen, since nobody is logged in yet! The only thing on the
screen is the XDM login prompt.
2: Somebody logged in.
Once someone has logged in through the XDM login window, the
situation is very different. For example: now it makes sense to
lock the screen (and prompt for the logged in user’s password);
and now xscreensaver should consult that user’s ~/.xscreensaver
file; and so on.
The difference between these two states comes down to a question of,
which user is the xscreensaver process running as? For the first
state, it doesn’t matter. If you start xscreensaver in the usual XDM
way, then xscreensaver will probably end up running as root, which is
fine for the first case (the ‘‘nobody logged in’’ case.)
However, once someone is logged in, running as root is no longer fine:
because xscreensaver will be consulting root’s .xscreensaver file
instead of that of the logged in user, and won’t be prompting for the
logged in user’s password, and so on. (This is not a security problem,
it’s just not what you want.)
So, once someone has logged in, you want xscreensaver to be running as
that user. The way to accomplish this is to kill the old xscreensaver
process and start a new one (as the new user.)
The simplest way to accomplish all of this is as follows:
1: Launch xscreensaver before anyone logs in.
To the file /usr/lib/X11/xdm/Xsetup, add the lines
xhost +localhost
xscreensaver-command -exit
xscreensaver &
This will run xscreensaver as root, over the XDM login window.
Moving the mouse will cause the screen to un-blank, and allow
the user to type their password at XDM to log in.
2: Restart xscreensaver when someone logs in.
Near the top of the file /usr/lib/X11/xdm/Xsession, add those
same lines:
xscreensaver-command -exit
xscreensaver &
When someone logs in, this will kill off the existing (root)
xscreensaver process, and start a new one, running as the user
who has just logged in. If the user’s .xscreensaver file
requests locking, they’ll get it. They will also get their own
choice of timeouts, and graphics demos, and so on.
Alternately, each user could just put those lines in their per‐
sonal ~/.xsession files.
Make sure you have $PATH set up correctly in the Xsetup and Xsession
scripts, or xdm won’t be able to find xscreensaver, and/or xscreensaver
won’t be able to find its graphics demos.
(If your system does not seem to be executing the Xsetup file, you may
need to configure it to do so: the traditional way to do this is to
make that file the value of the DisplayManager*setup resource in the
/usr/lib/X11/xdm/xdm-config file. See the man page for xdm(1) for more
details.)
It is safe to run xscreensaver as root (as xdm is likely to do.) If
run as root, xscreensaver changes its effective user and group ids to
something safe (like "nobody") before connecting to the X server or
launching user-specified programs.
An unfortunate side effect of this (important) security precaution is
that it may conflict with cookie-based authentication.
If you get "connection refused" errors when running xscreensaver from
xdm, then this probably means that you have xauth(1) or some other
security mechanism turned on. One way around this is to add
"xhost +localhost" to Xsetup, just before xscreensaver is launched.
Note that this will give access to the X server to anyone capable of
logging in to the local machine, so in some environments, this might
not be appropriate. If turning off file-system-based access control is
not acceptable, then running xscreensaver from the Xsetup file might
not be possible, and xscreensaver will only work when running as a nor‐
mal, unprivileged user.
For more information on the X server’s access control mechanisms, see
the man pages for X(1), Xsecurity(1), xauth(1), and xhost(1).
Using xscreensaver with gdm(1) is easy, because gdm has a configuration
tool. Just fire up gdmconfig(1) and on the Background page, type
"xscreensaver -nosplash" into the Background Program field. That will
cause gdm to run xscreensaver while nobody is logged in, and kill it as
soon as someone does log in. (The user will then be responsible for
starting xscreensaver on their own, if they want.)
Another way to accomplish the same thing is to edit the file
/etc/X11/gdm/gdm.conf to include:
BackgroundProgram=xscreensaver -nosplash
RunBackgroundProgramAlways=true
In this situation, the xscreensaver process will probably be running as
user gdm instead of root. You can configure the settings for this
nobody-logged-in state (timeouts, DPMS, etc.) by editing the
~gdm/.xscreensaver file.
To get gdm to run the BackgroundProgram, you may need to switch it from
the "Graphical Greeter" to the "Standard Greeter".
I understand that KDE has invented their own wrapper around xscreen‐
saver, that is inferior to xscreensaver-demo(1) in any number of ways.
I’ve never actually seen it, but I’m told that this is the way you dis‐
able it:
1: Switch off KDE s screen saver.
Open the ‘‘Control Center’’ and select the ‘‘Look and Feel /
Screensaver’’ page. Turn off the ‘‘Enable Screensaver’’ check‐
box.
2: Find your Autostart directory.
Open the ‘‘Look and Feel / Desktop / Paths’’ page, and see what
your ‘‘Autostart’’ directory is set to: it will probably be
~/.kde3/Autostart/ or something similar.
3: Make xscreensaver be an Autostart program.
Create a file in your autostart directory called xscreen‐
saver.desktop that contains the following five lines:
[Desktop Entry]
Exec=xscreensaver
Name=XScreensaver
Type=Application
X-KDE-StartupNotify=false
4: Make the various "lock session" buttons call xscreensaver.
Replace the file /usr/bin/kdesktop_lock with these two lines:
#!/bin/sh
xscreensaver-command -lock
Make sure the file is executable (chmod a+x).
Now use xscreensaver normally, controlling it via the usual xscreen
saver-demo(1) and xscreensaver-command(1) mechanisms.
The easiest way to use xscreensaver on a system with CDE is to simply
switch off the built-in CDE screensaver, and use xscreensaver instead;
and second, to tell the front panel to run xscreensaver-command(1) with
the -lock option when the Lock icon is clicked.
To accomplish this involves five steps:
1: Switch off CDE s locker
Do this by turning off ‘‘Screen Saver and Screen Lock’’ in the
Screen section of the Style Manager.
2: Edit sessionetc
Edit the file ~/.dt/sessions/sessionetc and add to it the line
xscreensaver &
And make sure the sessionetc file is executable. This will
cause xscreensaver to be launched when you log in. (As always,
make sure that xscreensaver and the graphics demos are on your
$PATH; the path needs to be set in .cshrc and/or .dtprofile, not
.login.)
3: Create XScreenSaver.dt
Create a file called ~/.dt/types/XScreenSaver.dt with the fol‐
lowing contents:
ACTION XScreenSaver
{
LABEL XScreenSaver
TYPE COMMAND
EXEC_STRING xscreensaver-command -lock
ICON Dtkey
WINDOW_TYPE NO_STDIO
}
This defines a ‘‘lock’’ command for the CDE front panel, that
knows how to talk to xscreensaver.
4: Create Lock.fp
Create a file called ~/.dt/types/Lock.fp with the following con‐
tents:
CONTROL Lock
{
TYPE icon
CONTAINER_NAME Switch
CONTAINER_TYPE SWITCH
POSITION_HINTS 1
ICON Fplock
LABEL Lock
PUSH_ACTION XScreenSaver
HELP_TOPIC FPOnItemLock
HELP_VOLUME FPanel
}
This associates the CDE front panel ‘‘Lock’’ icon with the lock
command we just defined in step 3.
5: Restart
Select ‘‘Restart Workspace Manager’’ from the popup menu to make
your changes take effect. If things seem not to be working,
check the file ~/.dt/errorlog for error messages.
Since CDE is a descendant of VUE, the instructions for using xscreen‐
saver under VUE are similar to the above:
1: Switch off VUE s locker
Open the ‘‘Style Manager’’ and select ‘‘Screen.’’ Turn off
‘‘Screen Saver and Screen Lock’’ option.
2: Make sure you have a Session
Next, go to the Style Manager’s, ‘‘Startup’’ page. Click on
‘‘Set Home Session’’ to create a session, then on ‘‘Return to
Home Session’’ to select this session each time you log in.
3: Edit vue.session
Edit the file ~/.vue/sessions/home/vue.session and add to it the
line
vuesmcmd -screen 0 -cmd "xscreensaver"
This will cause xscreensaver to be launched when you log in.
(As always, make sure that xscreensaver and the graphics demos
are on your $PATH; the path needs to be set in .cshrc and/or
.profile, not .login.)
3: Edit vuewmrc
Edit the file ~/.vue/vuewmrc and add (or change) the Lock con‐
trol:
CONTROL Lock
{
TYPE button
IMAGE lock
PUSH_ACTION f.exec "xscreensaver-command -lock"
HELP_TOPIC FPLock
}
This associates the VUE front panel ‘‘Lock’’ icon with the
xscreensaver lock command.
BUGS
Bugs? There are no bugs. Ok, well, maybe. If you find one, please
let me know. http://www.jwz.org/xscreensaver/bugs.html explains how to
construct the most useful bug reports.
Locking and XDM
If xscreensaver has been launched from xdm(1) before anyone has
logged in, you will need to kill and then restart the xscreen‐
saver daemon after you have logged in, or you will be confused
by the results. (For example, locking won’t work, and your
~/.xscreensaver file will be ignored.)
When you are logged in, you want the xscreensaver daemon to be
running under your user id, not as root or some other user.
If it has already been started by xdm, you can kill it by send‐
ing it the exit command, and then re-launching it as you, by
putting something like the following in your personal X startup
script:
xscreensaver-command -exit
xscreensaver &
The ‘‘Using XDM(1)’’ section, above, goes into more detail, and
explains how to configure the system to do this for all users
automatically.
Locking and root logins
In order for it to be safe for xscreensaver to be launched by
xdm, certain precautions had to be taken, among them that
xscreensaver never runs as root. In particular, if it is
launched as root (as xdm is likely to do), xscreensaver will
disavow its privileges, and switch itself to a safe user id
(such as nobody.)
An implication of this is that if you log in as root on the
console, xscreensaver will refuse to lock the screen (because
it can’t tell the difference between root being logged in on
the console, and a normal user being logged in on the console
but xscreensaver having been launched by the xdm(1) Xsetup
file.)
The solution to this is simple: you shouldn’t be logging in on
the console as root in the first place! (What, are you crazy
or something?)
Proper Unix hygiene dictates that you should log in as your‐
self, and su(1) to root as necessary. People who spend their
day logged in as root are just begging for disaster.
XAUTH and XDM
For xscreensaver to work when launched by xdm(1), programs run‐
ning on the local machine as user "nobody" must be able to con‐
nect to the X server. This means that if you want to run
xscreensaver on the console while nobody is logged in, you may
need to disable cookie-based access control (and allow all
users who can log in to the local machine to connect to the
display.)
You should be sure that this is an acceptable thing to do in
your environment before doing it. See the ‘‘Using XDM(1)’’
section, above, for more details.
Passwords
If you get an error message at startup like ‘‘couldn’t get
password of user’’ then this probably means that you’re on a
system in which the getpwent(3) library routine can only be
effectively used by root. If this is the case, then xscreen‐
saver must be installed as setuid to root in order for locking
to work. Care has been taken to make this a safe thing to do.
It also may mean that your system uses shadow passwords instead
of the standard getpwent(3) interface; in that case, you may
need to change some options with configure and recompile.
If you change your password after xscreensaver has been
launched, it will continue using your old password to unlock
the screen until xscreensaver is restarted. On some systems,
it may accept both your old and new passwords. So, after you
change your password, you’ll have to do
xscreensaver-command -restart
to make xscreensaver notice.
PAM Passwords
If your system uses PAM (Pluggable Authentication Modules),
then in order for xscreensaver to use PAM properly, PAM must be
told about xscreensaver. The xscreensaver installation process
should update the PAM data (on Linux, by creating the file
/etc/pam.d/xscreensaver for you, and on Solaris, by telling you
what lines to add to the /etc/pam.conf file.)
If the PAM configuration files do not know about xscreensaver,
then you might be in a situation where xscreensaver will refuse
to ever unlock the screen.
This is a design flaw in PAM (there is no way for a client to
tell the difference between PAM responding ‘‘I have never heard
of your module,’’ and responding, ‘‘you typed the wrong pass‐
word.’’) As far as I can tell, there is no way for xscreen‐
saver to automatically work around this, or detect the problem
in advance, so if you have PAM, make sure it is configured cor‐
rectly!
Colormap lossage: TWM
The installColormap option doesn’t work very well with the
twm(1) window manager and its descendants, on 8-bit screens.
There is a race condition between the screensaver and this
window manager, which can result in the screensaver’s colormap
not getting installed properly, meaning the graphics hacks will
appear in essentially random colors. (If the screen goes white
instead of black, this is probably why.)
The mwm(1) and olwm(1) window managers don’t have this problem.
The race condition exists because X (really, ICCCM) does not
provide a way for an OverrideRedirect window to have its own
colormap, short of grabbing the server (which is neither a good
idea, nor really possible with the current design.) What hap‐
pens is that, as soon as xscreensaver installs its colormap,
twm responds to the resultant ColormapNotify event by re-
installing the default colormap. Apparently, twm doesn’t
always do this; it seems to do it regularly if the screensaver
is activated from a menu item, but seems to not do it if the
screensaver comes on of its own volition, or is activated from
another console.
Attention, window manager authors!
You should only call XInstallColormap(3) in response to
user events. That is, it is appropriate to install a col‐
ormap in response to FocusIn, FocusOut, EnterNotify, and
LeaveNotify events; but it is not appropriate to call it in
response to ColormapNotify events. If you install col‐
ormaps in response to application actions as well as in
response to user actions, then you create the situation
where it is impossible for override-redirect applications
(such as xscreensaver) to display their windows in the
proper colors.
Colormap lossage: XV, XAnim, XEarth
Some programs don’t operate properly on visuals other than the
default one, or with colormaps other than the default one. See
the discussion of the magic "default-n" visual name in the
description of the programs resource in the Configuration sec‐
tion. When programs only work with the default colormap, you
need to use a syntax like this:
default-n: xv -root image-1.gif -quit \n\
default-n: xearth -nostars -wait 0 \n\
It would also work to turn off the installColormap option alto‐
gether, but that would deny extra colors to those programs that
can take advantage of them.
Machine Load
Although this program ‘‘nices’’ the subprocesses that it
starts, graphics-intensive subprograms can still overload the
machine by causing the X server process itself (which is not
‘‘niced’’) to consume many cycles. Care has been taken in all
the modules shipped with xscreensaver to sleep periodically,
and not run full tilt, so as not to cause appreciable load.
However, if you are running the OpenGL-based screen savers on a
machine that does not have a video card with 3D acceleration,
they will make your machine slow, despite nice(1).
Your options are: don’t use the OpenGL display modes; or, col‐
lect the spare change hidden under the cushions of your couch,
and use it to buy a video card manufactured after 1998. (It
doesn’t even need to be fast 3D hardware: the problem will be
fixed if there is any 3D hardware at all.)
XFree86 s Magic Keystrokes
The XFree86 X server traps certain magic keystrokes before
client programs ever see them. Two that are of note are
Ctrl+Alt+Backspace, which causes the X server to exit; and
Ctrl+Alt+Fn, which switches virtual consoles. The X server
will respond to these keystrokes even if xscreensaver has the
screen locked. Depending on your setup, you might consider
this a problem.
Unfortunately, there is no way for xscreensaver itself to over‐
ride the interpretation of these keys. If you want to disable
Ctrl+Alt+Backspace globally, you need to set the DontZap flag
in your /etc/X11/XF86Config file. To globally disable VT
switching, you can set the DontVTSwitch flag. See the XF86Con
fig(5) manual for details.
MIT Extension and Fading
The MIT-SCREEN-SAVER extension is junk. Don’t use it.
When using the MIT-SCREEN-SAVER extension in conjunction with
the fade option, you’ll notice an unattractive flicker just
before the fade begins. This is because the server maps a
black window just before it tells the xscreensaver process to
activate. The xscreensaver process immediately unmaps that
window, but this results in a flicker. I haven’t figured a way
to get around this; it seems to be a fundamental property of
the (mis-) design of this server extension.
It sure would be nice if someone would implement the SGI
SCREEN_SAVER extension in XFree86; it’s dead simple, and works
far better than the over-engineered and broken MIT-SCREEN-SAVER
extension.
Keyboard LEDs
If procInterrupts is on (which is the default on Linux systems)
and you’re using some program that toggles the state of your
keyboard LEDs, xscreensaver won’t work right: turning those
LEDs on or off causes a keyboard interrupt, which xscreensaver
will interpret as user activity. So if you’re using such a
program, set the procInterrupts resource to False.
Extensions
If you are not making use of one of the server extensions
(XIDLE, SGI SCREEN_SAVER, or MIT-SCREEN-SAVER), then it is pos‐
sible, in rare situations, for xscreensaver to interfere with
event propagation and make another X program malfunction. For
this to occur, that other application would need to not select
KeyPress events on its non-leaf windows within the first 30
seconds of their existence, but then select for them later. In
this case, that client might fail to receive those events.
This isn’t very likely, since programs generally select a con‐
stant set of events immediately after creating their windows
and then don’t change them, but this is the reason that it’s a
good idea to install and use one of the server extensions
instead, to work around this shortcoming in the X protocol.
In all these years, I’ve not heard of even a single case of
this happening, but it is theoretically possible, so I’m men‐
tioning it for completeness...
ENVIRONMENT
DISPLAY to get the default host and display number, and to inform the
sub-programs of the screen on which to draw.
PATH to find the sub-programs to run.
HOME for the directory in which to read the .xscreensaver file.
XENVIRONMENT
to get the name of a resource file that overrides the global
resources stored in the RESOURCE_MANAGER property.
UPGRADES
The latest version of xscreensaver, an online version of this manual,
and a FAQ can always be found at http://www.jwz.org/xscreensaver/
X(1), Xsecurity(1), xauth(1), xdm(1), gdm(1), xhost(1), xscreen
saver-demo(1), xscreensaver-command(1), xscreensaver-gl-helper(1),
xscreensaver-getimage(1), xscreensaver-text(1).
COPYRIGHT
Copyright © 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
2001, 2002, 2003, 2004, 2005 by Jamie Zawinski. Permission to use,
copy, modify, distribute, and sell this software and its documentation
for any purpose is hereby granted without fee, provided that the above
copyright notice appear in all copies and that both that copyright
notice and this permission notice appear in supporting documentation.
No representations are made about the suitability of this software for
any purpose. It is provided "as is" without express or implied war‐
ranty.
AUTHOR
Jamie Zawinski <jwz@jwz.org>. Written in late 1991; version 1.0 posted
to comp.sources.x on 17-Aug-1992.
Please let me know if you find any bugs or make any improvements.
ACKNOWLEDGEMENTS
Thanks to Angela Goodman for the XScreenSaver logo.
Thanks to the many people who have contributed graphics demos to the
package.
Thanks to David Wojtowicz for implementing lockTimeout.
Thanks to Martin Kraemer for adding support for shadow passwords and
locking-disabled diagnostics.
Thanks to Patrick Moreau for the VMS port.
Thanks to Nat Lanza for the Kerberos support.
Thanks to Bill Nottingham for the initial PAM support.
And thanks to Jon A. Christopher for implementing the Athena dialog
support, back in the days before Lesstif or Gtk were viable alterna‐
tives to Motif.