XScreenSaver(1)

NAME
xscreensaver - extensible screen saver and screen locking framework

SYNOPSIS
xscreensaver [--display host:display.screen] [--verbose] [--version] [--no-splash] [--log filename]

DESCRIPTION
XScreenSaver waits until the user is idle, and then runs graphics demos chosen at random. It can also lock your screen, and provides configuration and control of display power management. XScreenSaver is also available on macOS, iOS and Android.

GETTING STARTED
XScreenSaver is a daemon that runs in the background. You configure it with the xscreensaver-settings(1) program.

	xscreensaver &
	xscreensaver-settings

HOW IT WORKS
When it is time to activate the screensaver, a full-screen black window is created that covers each monitor. A sub-process is launched for each one running a graphics demo, pointed at the appropriate window. Because of this, any program which can draw on a provided window can be used as a screensaver. The various graphics demos are, in fact, just standalone programs that do that. When the user becomes active again, the screensaver windows are unmapped, and the running subprocesses are killed. The display modes are run at a low process priority, and spend most of their time sleeping/idle by default, so they should not consume significant system resources.

COMMAND-LINE OPTIONS

--display host:display.screen
    The X display to use. For displays with multiple screens, XScreenSaver will manage all screens on the display simultaneously.

--verbose
    Print diagnostics to stderr.

--version
    Print the version number and exit.

--log filename
    Append all diagnostic output to the given file. This also implies --verbose. Use this when reporting bugs.

--no-splash
    Don't display the splash screen at startup.

POWER MANAGEMENT
The xscreensaver-settings(1) program is where you configure if and when your monitor should power off. It saves the settings in your ~/.xscreensaver file. Do not use xset(1) to manually change the power management settings, that won't work. When the monitor is powered down, the display hacks will stop running (though it may take a minute or two for XScreenSaver to notice).

LAPTOP LIDS
If your system uses systemd(1) or elogind(8), then closing the lid of your laptop will cause the screen to lock immediately. If not, then the screen might not lock until a few seconds after you re-open the lid. Which is less than ideal. So if you do not have systemd(1), you might want to get in the habit of manually locking your screen before closing the lid (xscreensaver-command --lock).

PLAYING VIDEOS
Likewise, if you have systemd(1) or elogind(8), then all of the popular video players and web browsers will prevent XScreenSaver from blanking the screen while video is playing. Both of these features require that xscreensaver-systemd(6) be able connect to D-Bus.

INSTALLATION
Each desktop environment has its own system for launching long-running daemons like XScreenSaver, and since many of them come bundled with their own (buggy, insecure, inferior) screen-locking frameworks, it is also necessary to disable those other frameworks before XScreenSaver can work.

  INSTALLING XSCREENSAVER ON GNOME OR UNITY
For many years, GNOME included XScreenSaver as-is, and everything just worked. Not any more!

    1: Fully uninstall the other screen saver packages:

        	sudo apt remove gnome-screensaver
        	sudo apt remove mate-screensaver
        	sudo apt remove cinnamon-screensaver
        	sudo apt remove light-locker
        or
        	sudo rpm -e gnome-screensaver
        	sudo rpm -e mate-screensaver
        	sudo rpm -e cinnamon-screensaver
        	sudo rpm -e light-locker

        Be careful that it doesn't try to uninstall all of GNOME.

    2: Turn off GNOME's built-in blanking.
        Set all of the following settings to "Never" or "Off", as these are all controlled by xscreensaver-settings(1) now: "Settings / Privacy / Screen Lock / Blank Screen Delay"
        "Settings / Privacy / Screen Lock / Automatic Screen Lock"
        "Settings / Power / Blank Screen"
        "Settings / Power / Automatic Suspend"

    3: Launch XScreenSaver at login.
        Launch "Tweaks", select "Startup Applications", click the plus sign, and select "XScreenSaver" (not "XScreenSaver Settings") from the (very long) menu. Or, see the "LAUNCHING XSCREENSAVER FROM SYSTEMD" section below. That works too.

    4: Make GNOME's "Lock" icon use XScreenSaver.
        This used to work, but no longer does with GNOME 3.38. If you figure it out, let me know! This still works for Cinnamon 4.8 and MATE 1.24:

        	sudo ln -sf /usr/bin/xscreensaver-command \
        	       /usr/bin/gnome-screensaver-command
        	sudo ln -sf /usr/bin/xscreensaver-command \
        	    /usr/bin/cinnamon-screensaver-command
        	sudo ln -sf /usr/bin/xscreensaver-command \
        	        /usr/bin/mate-screensaver-command
        	sudo ln -sf /usr/bin/xscreensaver-command \
        	       /usr/bin/xfce4-screensaver-command
        	sudo ln -sf /usr/bin/xscreensaver-command \
        	            /usr/bin/light-locker-command

        This change will get blown away when you upgrade.

  INSTALLING XSCREENSAVER ON KDE
Like GNOME, KDE also decided to re-invent the wheel. To replace the KDE screen saver with XScreenSaver, do the following:

    1: Turn off KDE's built-in blanking.
        In System Settings, un-check the following items, as these are controlled by xscreensaver-settings(1) now: "Workspace Behavior / Screen Locking / Lock automatically"
        "Workspace Behavior / Screen Locking / After waking from sleep"
        "Workspace Behavior / Screen Locking / Keyboard shortcut"
        "Hardware / Power Management / Screen Energy Saving"
        "Hardware / Power Management / Suspend session"
        "Hardware / Power Management / Laptop lid closed" = Do Nothing If there are multiple tabs, you may need to change these settings on all three of them: "On AC power", "Battery" and "Low Battery".

    2: Launch XScreenSaver at login.
        Copy the file /usr/share/applications/xscreensaver.desktop into the directory ~/.config/autostart/

    3: Make KDE's "Lock" icon use XScreenSaver.
        Find the "kscreenlocker_greet" program. It might be in "/usr/lib/*/libexec/", or it might be somewhere else. Delete that file and replace it with a file containing these two lines. Make it executable (chmod a+x).

        	#!/bin/sh
        	xscreensaver-command --lock &

        This change will get blown away when you upgrade.

    4: Turn off KDE's built-in locking on suspend, even harder.
        Even after disabling KDE's screen locking, above, it is possible that KDE will still use its built-in locker when you close your laptop's lid. If that is happening, double-check the settings above, but if those are correct, try the following. First, ensure you are running KDE 5.21 or newer. Next, enable "systemd user sessions" for KDE so that you can edit the parameters for ksmserver:

        	kwriteconfig5 --file startkderc --group General \
        	  --key systemdBoot true

        Log out and back in. Next, edit the plasma-ksmserver service to change how ksmserver is launched:

        	systemctl edit --user plasma-ksmserver.service

        Replace the contents of the file that lets you edit with this:

        	[Service]
        	ExecStart=
        	ExecStart=/usr/bin/ksmserver --no-lockscreen

        Then log out and back in again.

  LAUNCHING XSCREENSAVER FROM LXDE
Add the line @xscreensaver to /etc/xdg/lxsession/LXDE/autostart or /etc/xdg/lxsession/LXDE-pi/autostart.

  LAUNCHING XSCREENSAVER FROM SYSTEMD
If you are not using GNOME, KDE or LXDE, the way to launch XScreenSaver at login is probably systemd(1). If the file /usr/lib/systemd/user/xscreensaver.service does not already exist, copy the file /usr/share/xscreensaver/xscreensaver.service to there or to ~/.config/systemd/user/. Then enable it with:

	systemctl --user enable xscreensaver

  LAUNCHING XSCREENAVER FROM UPSTART
If you are not using GNOME, KDE or LXDE, and your system uses upstart(7) instead of systemd(1), launch the "Startup Applications" applet, click "Add", and enter these lines:

	Name: XScreenSaver
	Command: xscreensaver
	Comment: XScreenSaver

  LAPTOP LIDS WITHOUT SYSTEMD
BSD systems or other systems without systemd(1) or elogind(8) might have luck by adding "xscreensaver-command --suspend" to some appropriate spot in /etc/acpi/events/anything or in /etc/acpi/handler.sh, if those files exist.

  LAUNCHING XSCREENSAVER FROM GDM
You can run xscreensaver from your gdm(1) session, so that the screensaver will run even when nobody is logged in on the console. To do this, run gdmconfig(1). On the General page set the Local Greeter to Standard Greeter. On the Background page, type the command "xscreensaver --no-splash" 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.) If that doesn't work, you can edit the config file directly. Edit /etc/X11/gdm/gdm.conf or maybe /etc/gdm3/custom.conf to include:

	Greeter=/usr/bin/gdmlogin
	BackgroundProgram=xscreensaver --no-splash
	RunBackgroundProgramAlways=true

In this situation, the xscreensaver process will be running as user gdm. You can configure the settings for this nobody-logged-in state (timeouts, DPMS, etc.) by editing the ~gdm/.xscreensaver file. If you get "connection refused" errors when running xscreensaver from gdm, then this probably means that you are having xauth(1) problems. For information on the X server's access control mechanisms, see the man pages for X(1), Xsecurity(1), xauth(1), and xhost(1). There might be a way to accomplish this with other display managers. It's a mystery!

THE WAYLAND PROBLEM
Wayland is a completely different window system that is intended to replace X11. After 16+ years of trying, some Linux distros have finally begun enabling it by default. Most deployments of it also include XWayland, which is a compatibility layer that allows some X11 programs to continue to work within a Wayland environment. Unfortunately, XScreenSaver is not one of those programs. If your system is running Wayland, XScreenSaver will malfunction in a few ways, some small but one quite serious:

    1: It will be unable to lock the screen.
        This is because X11 grabs don't work properly under XWayland, so there is no way for XScreenSaver to prevent the user from switching away from the screen locker to another application.

    2: It won't work at all under GNOME.
        This is because the GNOME compositor does not support either of the Wayland protocols that allow us to tell when the user is idle. It works with KDE and most other compositors, however.

    2: No mouse hystersis.
        Even a single pixel of mouse motion will cause the screen to un-blank.

    3: Fading and screenshots might not work.
        Under Wayland, Fading in and out, and allowing hacks to grab and manipulate a desktop screenshot, depend on the program grim(1) being installed to grab screenshots for us. And grim(1) doesn't work under the GNOME or KDE compositors.
For XScreenSaver to be able to lock, you will need to switch off Wayland and use the X Window System like in the "good old days".

  TO DISABLE WAYLAND UNDER GNOME
The login screen should have a gear-icon menu that lets you change the session type from "GNOME" (the Wayland session) to "GNOME on Xorg" (the X11 session). Alternately, edit /etc/X11/gdm/gdm.conf or maybe /etc/gdm3/custom.conf to include:

	WaylandEnable=false

  TO DISABLE WAYLAND UNDER KDE
The login screen should have a menu that lets you change the session type to "Plasma (X11)". Alternately, edit /etc/sddm.conf and change the SessionDir line under the [Wayland] section to say:

	SessionDir=/dev/null

SECURITY CONCERNS
XScreenSaver has a decades-long track record of securely locking your screen. However, there are many things that can go wrong. X11 is a very old system, and has a number of design flaws that make it susceptible to foot-shooting.

  MAGIC BACKDOOR KEYSTROKES
The Xorg and XFree86 X servers, as well as the Linux kernel, both trap certain magic keystrokes before X11 client programs ever see them. If you care about keeping your screen locked, this is a big problem.

Ctrl+Alt+Backspace
    This keystroke kills the X server, and on some systems, leaves you at a text console. If the user launched X11 manually, that text console will still be logged in. To disable this keystroke globally and permanently, you need to set the DontZap flag in your xorg.conf(5) or XF86Config(5) file.

Ctrl-Alt-F1, Ctrl-Alt-F2, etc.
    These keystrokes will switch to a different virtual console, while leaving the console that X11 is running on locked. If you left a shell logged in on another virtual console, it is unprotected. So don't leave yourself logged in on other consoles. You can disable VT switching globally and permanently by setting DontVTSwitch in your xorg.conf(5), but that might make your system harder to use, since VT switching is an actual useful feature. There is no way to disable VT switching only when the screen is locked. It's all or nothing.

Ctrl-Alt-KP_Multiply
    This keystroke kills any X11 app that holds a lock, so typing this will kill XScreenSaver and unlock the screen. You can disable it by turning off AllowClosedownGrabs in xorg.conf(5).

Alt-SysRq-F
    This is the Linux kernel "OOM-killer" keystroke. It shoots down random long-running programs of its choosing, and so might target and kill XScreenSaver. You can disable this keystroke globally with:

    	echo 176 > /proc/sys/kernel/sysrq

    There's little that I can do to make the screen locker be secure so long as the kernel and X11 developers are actively working against security like this. The strength of the lock on your front door doesn't matter much so long as someone else in the house insists on leaving a key under the welcome mat.

  THE OOM-KILLER
Even if you have disabled the Alt-SysRq-F OOM-killer keystroke, the OOM-killer might still decide to assassinate XScreenSaver at random, which will unlock your screen. If the xscreensaver-auth(6) program is installed setuid, it attempts to tell the OOM-killer to leave the XScreenSaver daemon alone, but that may or may not work. You would think that the OOM-killer would pick the process using the most memory, but most of the time it seems to pick the process that would be most comically inconvenient, such as your screen locker, or crond(8). You can disable the OOM-killer entirely with:

	echo 2 > /proc/sys/vm/overcommit_memory
	echo vm.overcommit_memory = 2 >> /etc/sysctl.conf

In addition to the kernel's OOM-killer, systemd(1) has its own. The included xscreensaver.service file attempts to evade it, but you may want to just turn it off anyway:

	sudo systemctl disable --now systemd-oomd
	sudo systemctl mask systemd-oomd

  X SERVER ACCESS IS GAME OVER
X11's security model is all-or-nothing. If a program can connect to your X server at all, either locally or over the network, it can log all of your keystrokes, simulate keystrokes, launch arbitrary programs, and change the settings of other programs. Assume that anything that can connect to your X server can execute arbitrary code as the logged-in user. See Xsecurity(1) and xauth(1).

  PAM PASSWORDS
If your system uses PAM (Pluggable Authentication Modules), then PAM must be configured for XScreenSaver. If it is not, then you might be in a situation where you can't unlock. Probably the file you need is /etc/pam.d/xscreensaver.

  DON'T LOG IN AS ROOT
Never log in as root. Log in as a normal user and use sudo(1) as necessary. If you are logged in as root, XScreenSaver will not lock your screen or run display modes, for numerous good and proper reasons.

MULTI-USER OR SITE-WIDE CONFIGURATION
For a single user, the proper way to configure XScreenSaver is to simply run the xscreensaver-settings(1) program, and change the settings through the GUI. Changes are written to the ~/.xscreensaver file. If you want to set the system-wide defaults, then make your edits to /etc/X11/app-defaults/XScreenSaver instead. The two files have similar (but not identical) syntax. You can also make changes via the X Resource Database and xrdb(1), but that can be very confusing and is not really recommended. Options in ~/.xscreensaver override any settings in the resource database or app-defaults file. If you change a setting in the .xscreensaver file while XScreenSaver is already running, it will notice this, and reload the file as needed. But if you change a setting in the X Resource Database, you will need to restart XScreenSaver for those changes to take effect:

	xrdb < ~/.Xdefaults
	xscreensaver-command --restart

X RESOURCES
These are the X resources use by XScreenSaver program. You probably won't need to change these manually: that's what the xscreensaver-settings(1) program is for.

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. If there are multiple screens, the savers are staggered slightly so that while they all change every cycle minutes, they don't all change at the same time.

lock (class Boolean)
    Enable locking: before the screensaver will turn off, it will require you to type the password of the logged-in user.

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, lockTimeout 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). A few seconds are added each time you type a character.

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.

verbose (class Boolean)
    Whether to print diagnostics. Default false.

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.

demoCommand (class DemoCommand)
    This is the shell command run when the Demo button on the splash window is pressed. It defaults to xscreensaver-settings(1).

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 gdmflexiserver(1), kdmctl(1), lxdm(1) or dm-tool(1).

nice (class Nice)
    The sub-processes launched 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 nice(1) for details.)

fade (class Boolean)
    If this is true, then when the screensaver activates, the desktop will fade to black instead of simply winking out. Default: true.

unfade (class Boolean)
    If this is true, then when the screensaver deactivates, desktop will fade back ininstead of appearing immediately. This is only done if fade is true as well. Default: true.

fadeSeconds (class Time)
    If fade is true, this is how long the fade will be in seconds. Default 3 seconds.

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-settings(1) program will suppress the non-existent programs from the list if this is true. Default: false.

authWarningSlack (class Integer)
    After you successfully unlock the screen, a dialog may pop up informing you of previous failed login attempts. If all of those login attemps were within this amount of time, they are ignored. The assumption is that incorrect passwords entered within a few seconds of a correct one are user error, rather than hostile action. Default 20 seconds.

mode (class Mode)
    Controls the screen-saving behavior. Valid 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 setting).

    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-settings(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-settings(1) program). 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. The default XScreenSaver hacks directory (typically /usr/libexec/xscreensaver/) is prepended to $PATH before searching for these programs. To use a program as a screensaver, it must be able to render onto the window provided to it in the $XSCREENSAVER_WINDOW environment variable. If it creates and maps its own window instead, it won't work. It must render onto the provided window. Visuals: 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:

    default-n
        This is like default, but also requests the use of the default colormap, instead of a private colormap.

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.

visualID (class VisualID)
    This is an historical artifact left over from when 8-bit displays were still common. You should probably ignore this. 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.) Valid 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 behavior 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, TrueColor, GrayScale, PseudoColor, or DirectColor. Selects the deepest visual of the given class.

    N   where number (decimal or hex) is interpreted as a visual id number, as reported by the xdpyinfo(1) program; 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, above.

installColormap (class Boolean)
    This is an historical artifact left over from when 8-bit displays were still common. 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. (Which, in this century, you do.)

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. A single pixel of motion will still cause the monitor to power back on, but not un-blank. This is because the X11 server itself unfortunately handles power-management-related activity detection rather than XScreenSaver.

BUGS
https://www.jwz.org/xscreensaver/bugs.html explains how to write the most useful bug reports. If you find a bug, please let me know!

ENVIRONMENT

DISPLAY
    to get the default host and display number, and to inform the sub-programs of the screen on which to draw.

XSCREENSAVER_WINDOW
    Passed to sub-programs to indicate the ID of the window on which they should draw.

PATH
    to find the sub-programs to run, including the display modes.

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 https://www.jwz.org/xscreensaver/

SEE ALSO
X(1), Xsecurity(1), xauth(1), xdm(1), gdm(1), xhost(1), systemd(1), elogind(8), xscreensaver-settings(1), xscreensaver-command(1), xscreensaver-systemd(6), xscreensaver-gl-helper(6), xscreensaver-getimage(6), xscreensaver-text(6).

COPYRIGHT
Copyright © 1991-2026 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 warranty.

AUTHOR
Jamie Zawinski <jwz@jwz.org> 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 three decades!