Provided by: xscreensaver_6.02+dfsg1-2ubuntu1_amd64 bug


       xscreensaver - extensible screen saver and screen locking framework


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


       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

       XScreenSaver is also available on macOS, iOS and Android.


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

            xscreensaver &


       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.


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

               Print diagnostics to stderr.

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

               Don't display the splash screen at startup.


       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.

       If  the  power  management  section  is grayed out in the xscreensaver-settings(1) window,
       then that means that your X server does not support the XDPMS extension,  and  so  control
       over the monitor's power state is not available.

       When  the  monitor  is  powered  down, the display hacks are stopped (though it may take a
       minute or two for XScreenSaver to notice).

       Note: if you use xset(1) to  change  the  power  management  settings,  XScreenSaver  will
       override those changes.  Whatever is in the ~/.xscreensaver file takes precedence.


       If  your  system  has systemd(1) 221 or newer, 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 don't use systemd, you might want to get in the habit
       of doing xscreensaver-command --lock before closing the lid.


       Likewise, if you have systemd(1) 221 or newer, 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 the systemd
       bus.  Parts of KDE and GNOME may need to be disabled first for that to work; see below.


       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.

       For many years, GNOME shipped XScreenSaver as-is, and everything just  worked.   In  2005,
       however, they decided to needlessly re-invent the wheel and ship their own replacement for
       the xscreensaver daemon called gnome-screensaver(1) rather than improving XScreenSaver and
       contributing  their changes back.  As a result, the gnome-screensaver program is insecure,
       bug-ridden, and missing many features of XScreenSaver.  In  fact,  in  2011  it  lost  the
       ability to run display modes at all.

       In  2012  some  distros  forked  and  renamed it as both mate-screensaver(1) and cinnamon-
       screensaver(1), which seem to be basically the same.

       To replace gnome-screensaver with XScreenSaver:

           1: Fully uninstall the other screen saver packages:

                   sudo apt-get remove gnome-screensaver
                   sudo apt-get remove mate-screensaver
                   sudo apt-get remove cinnamon-screensaver
                   sudo rpm -e gnome-screensaver
                   sudo rpm -e mate-screensaver
                   sudo rpm -e cinnamon-screensaver

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

           2: Launch XScreenSaver at login.

              Select "Startup Applications" from the menu  (or  manually  launch  "gnome-session-
              properties")  and  add "xscreensaver".  Do this as your normal user account, not as

           3: Make GNOME's "Lock Screen" use XScreenSaver.

                   sudo ln -sf /usr/bin/xscreensaver-command \

           4: Turn off Unity's built-in blanking.

              Open "System Settings / Brightness & Lock";
              Un-check "Start Automatically";
              Set "Turn screen off when inactive for" to "Never".

              Or possibly that has been randomly renamed again:
              Set "Settings / Power / Power Settings" to "Never".

           5: Stop GNOME from blocking XScreenSaver's "systemd" integration:

                   sudo systemctl --user mask gsd-screensaver-proxy.service
                   sudo systemctl --user mask \

              Without the above, video players will not be able to tell XScreenSaver not to blank
              the  screen  while  videos  are playing, and the screen will not auto-lock when you
              close your laptop's lid.

              After running those commands, reboot.  Yes, you have to reboot; it  won't  let  you
              simply stop the service.  Logging out won't do it either.

       Like  GNOME,  KDE  also  decided  to  invent their own screen saver framework from scratch
       instead of simply using XScreenSaver.  To replace the KDE screen saver with  XScreenSaver,
       do the following:

           1: Turn off KDE's screen saver.
              Open  the "Control Center" and select the "Appearance & Themes / Screensaver" page.
              Un-check "Start Automatically".

              Or possibly: Open "System Settings" and select "Screen  Locking".   Un-check  "Lock
              Screen 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   something   like   ~/.kde/Autostart/   or

              If that doesn't work, then try this:

              Open   "System   Settings   /   Startup/Shutdown   /   Autostart",   and  then  add

              If you are lucky, that will  create  an  "xscreensaver.desktop"  file  for  you  in
              ~/.config/autostart/ or ~/.kde/Autostart/.

           3: Make XScreenSaver be an Autostart program.
              If  it  does  not  already  exist, create a file in your autostart directory called
              xscreensaver.desktop that contains the following six lines:

                   [Desktop Entry]

           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:

                   xscreensaver-command --lock

              Make sure the file is executable (chmod a+x).

              This change will probably get blown away the next time your system upgrades KDE.

           5: Stop KDE from blocking XScreenSaver's "systemd" integration:
              You must arrange for KDE's ksmserver(1) daemon to be launched with the command line
              option --no-lockscreen.

              Under  KDE  5.00  through  5.16, you can accomplish that by editing the startkde(1)
              script in /usr/bin/ by hand, then logging out and back in again.

              Under KDE 5.17 through 5.20, you must wrap ksmserver(1) instead:

                   mv /usr/bin/ksmserver /usr/bin/ksmserver-orig

              and replace /usr/bin/ksmserver with:

                   ksmserver-orig --no-lockscreen

              Either change will, of course, get blown away the next time  your  system  upgrades

              Instead  of  being  in  /usr/bin/,  the  ksmserver program might be in /usr/lib/ or
              /usr/lib*/libexec/ or usr/lib/*/libexec/  or  somewhere  else,  depending  on  your

              Under KDE 5.21+ this might work instead, and might persist through upgrades:

                   systemctl edit plasma-ksmserver.service

              and then put this in the file you get to edit:

                   ExecStart=/usr/bin/ksmserver --no-lockscreen

              Regardless  of  which approach you need to use, if you do not force ksmserver(1) to
              stop squatting on the DBus endpoint,  video  players  will  not  be  able  to  tell
              XScreenSaver  not to blank the screen while videos are playing, and the screen will
              not auto-lock when you close your laptop's lid.

       If the above didn't do it, and your system has systemd(1), maybe this is how it works:

           1: Create a service.
              Create the file ~/.config/systemd/user/xscreensaver.service containing:


           2. Enable it.

                   systemctl --user enable xscreensaver

       Then restart X11.

       If your system has upstart(7) instead of systemd(1), maybe  this  will  work:  launch  the
       "Startup Applications" applet, click "Add", enter these lines, then restart X11:

            Name: XScreenSaver
            Command: xscreensaver
            Comment: XScreenSaver

       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  --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.)

       If that doesn't work, you can edit the config file directly. Edit /etc/X11/gdm/gdm.conf to

            BackgroundProgram=xscreensaver --nosplash

       In this situation, the xscreensaver process will probably be running as user  gdm  instead
       of  as  root.   You  can configure the settings for this nobody-logged-in state (timeouts,
       DPMS, etc.) by editing the ~gdm/.xscreensaver file.

       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 xauth(1) or some other security  mechanism  turned  on.   For
       information  on  the  X  server's  access  control mechanisms, see the man pages for X(1),
       Xsecurity(1), xauth(1), and xhost(1).

       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/, if those files exist.


       Wayland is a completely different window system that is intended to  replace  X11.   After
       13+  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 XWayland, XScreenSaver will malfunction in two ways:

       1: It will be unable to detect user activity in non-X11 programs.

          This  means  that  while  a native Wayland program is selected, XScreenSaver will think
          that you are idle, and may blank the screen prematurely.

       2: 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

       In short, for XScreenSaver to work properly, you will need to switch off Wayland  and  use
       the X Window System like in the "good old days".

       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/gdm/custom.conf and make sure it includes this line:


       The login screen should have a menu that lets you  change  the  session  type  to  "Plasma

       Alternately,  edit  /etc/sddm.conf  and  change  the  SessionDir  line under the [Wayland]
       section to say:



       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.

       The XFree86 and Xorg 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.

          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  or  XF86Config or XF86Config-4 file, depending which is in use on your
          system.  See XF86Config(5) for details.

       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, 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

          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.

          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.

       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

       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).

       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.

       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).

       Proper Unix hygiene dictates that you should log in as yourself, and sudo(1)  to  root  as
       necessary.  People who spend their day logged in as root are just begging for disaster.


       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.   The  rest  of
       this  manual  describes lower-level ways of changing settings.  You shouldn't need to know
       any of the stuff described below unless you are trying to do something complicated.

       Options to XScreenSaver are stored in one of two places: in a  file  called  .xscreensaver
       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  n  the .xscreensaver file, you would write the

            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 as needed.

       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  /etc/X11/app-defaults/XScreenSaver,  but
       different systems might keep it in a different place.

       When settings are changed in the Preferences dialog box, those settings are written to the
       .xscreensaver file.  The .Xdefaults file and the app-defaults file will never  be  written
       by XScreenSaver itself.


       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

               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

       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.   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-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 current contents of the
               screen will fade to black instead of simply winking out.  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 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.

                       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

       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.

               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

               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


               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:

                    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

               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 explains how  to  write  the  most  useful  bug
       reports.  If you find a bug, please let me know!


       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, including the display modes.

       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.


       The latest version of XScreenSaver, an online version of this manual, and a FAQ can always
       be found at


       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 © 1991-2021 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.


       Jamie  Zawinski <>.  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.

       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!