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-saving features.
xscreensaver & xscreensaver-demo
Note that xscreensaver has a client-server model: the xscreensaver program is a daemon that runs in the background;
it is controlled by the foreground
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 .xscreensaver 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 .Xdefaults file; for example, to set the timeout parameter in the .xscreensaver file, you would write the following:
whereas, in the .Xdefaults file, you would write
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/openwin/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 .Xdefaults file and the app-defaults file will never be written by xscreensaver itself.)
|The X display to use. For displays with multiple screens, XScreenSaver will manage all screens on the display simultaniously.|
|-verbose||Same as setting the verbose resource to true: print diagnostics on stderr and on the xscreensaver window.|
|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.|
|This is exactly the same as redirecting stdout and stderr to the given file (for append). This is useful when reporting bugs.|
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 screensaver decides that it's time to run a different demo: the old one is killed and a new one is launched.
You can control a running screensaver process by using the
The ~/.xscreensaver file controls the configuration of your
display's power management settings: if you have used
To change your power management settings, run
If the power management section is grayed out in the
If you're using a laptop, don't be surprised if changing the DPMS settings 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
To replace gnome-screensaver with xscreensaver:
1: Fully uninstall the gnome-screensaver package.
sudo apt-get remove gnome-screensaver
2: Launch xscreensaver at login. Select "Startup Applications" from the menu (or manually launch "gnome-session-properties") and add "xscreensaver". 3: Make "Lock Screen" use xscreensaver.
sudo ln -sf /usr/bin/xscreensaver-command \ /usr/bin/gnome-screensaver-command
1: Turn off KDE's screen saver. Open the "Control Center" and select the "Appearance & Themes / Screensaver" page. Un-check "Start Automatically". 2: Find your Autostart directory. Open the "System Administration / Paths" page, and see what your "Autostart path" is set to: it will probably be ~/.kde/Autostart/ or something similar. 3: Make xscreensaver be an Autostart program. Create a .desktop file in your autostart directory called xscreensaver.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. The file you want to replace next has moved around over the years. It might be called /usr/libexec/kde4/kscreenlocker, or it might be called "kdesktop_lock" or "krunner_lock" or "kscreenlocker_greet", and it might be in /usr/lib/kde4/libexec/ or in /usr/kde/3.5/bin/ or even in /usr/bin/, depending on the distro and phase of the moon. Replace the contents of that file 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
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".
It is safe to run xscreensaver as root (as xdm or gdm may 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 gdm, then this probably means that you have
|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
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 yourself, and
|XAUTH and XDM|
For xscreensaver to work when launched by
You should be sure that this is an acceptable thing to do in your environment before doing it. See the "Using GDM" section, above, for more details.
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
It also may mean that your system uses shadow passwords instead of the standard
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
to make xscreensaver notice.
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 password".) As far as I can tell, there is no way for xscreensaver to automatically work around this, or detect the problem in advance, so if you have PAM, make sure it is configured correctly!
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
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
Your options are: don't use the OpenGL display modes; or, collect 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 override 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
|timeout (class Time)|
|The screensaver will activate (blank the screen) after the keyboard 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
|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 activation) 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 powers down completely. Note that these settings will have no effect unless both the X server and the display hardware support power management; not all do. See the Power Management section, below, for more information.|
|dpmsQuickOff (class Boolean)|
|If mode is blank and this is true, then the screen will be powered down immediately upon blanking, regardless of other power-management settings.|
|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:
|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 automatically.) 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 diagnostic 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.|
|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
|prefsCommand (class PrefsCommand)|
|This is the shell command run when the Prefs button on the splash window is pressed. It defaults to xscreensaver-demo -prefs.|
|newLoginCommand (class NewLoginCommand)|
If set, this is the shell command that is run when the "New Login" button
is pressed on the unlock dialog box, in order to create a new desktop
session without logging out the user who has locked the screen.
Typically this will be some variant of
|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 unnecessarily. The default is 10.
(Higher numbers mean lower priority; see
|fade (class Boolean)|
|If this is true, then when the screensaver activates, the current contents of the screen will fade to black instead of simply 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 controlling 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
|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:
|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
|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
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 system-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 disables 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
Because xscreensaver was created back when dinosaurs roamed the earth, it still contains support for some things you've probably never seen, such as 1-bit monochrome monitors, grayscale monitors, and monitors capable of displaying only 8-bit colormapped images.
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:
|You shouldn't ever need to change the following resources:|
|pointerPollTime (class Time)|
|When server extensions are not in use, this controls how frequently 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...)|
|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, xscreensaver 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 console 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 screenhack. 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 captureStderr is true. Default: Yellow.|
|overlayTextBackground (class Background)|
|The background color used for the stdout/stderr text, if captureStderr is true. Default: Black.|
|bourneShell (class BourneShell)|
|The pathname of the shell that xscreensaver uses to start subprocesses. This must be whatever your local variant of /bin/sh is: in particular, it must not be csh.|
|DISPLAY||to get the default host and display number, and to inform the sub-programs of the screen on which to draw.|
|Passed to sub-programs to indicate the ID of the window on which they should draw. This is necessary on Xinerama/RANDR systems where multiple physical monitors share a single X11 "Screen".|
|PATH||to find the sub-programs to run.|
|HOME||for the directory in which to read the .xscreensaver file.|
|to get the name of a resource file that overrides the global resources stored in the RESOURCE_MANAGER property.|
Please let me know if you find any bugs or make any improvements.
And a huge thank you to the hundreds of people who have contributed, in large ways and small, to the xscreensaver collection over the past two decades!