Provided by: xscreensaver_5.04-4ubuntu1_i386 bug

NAME

       xscreensaver - extensible screen saver framework, plus locking

SYNOPSIS

       xscreensaver       [-display       host:display.screen]      [-verbose]
       [-no-capture-stderr] [-no-splash]

DESCRIPTION

       The xscreensaver program waits until the keyboard and mouse  have  been
       idle  for a period, and then runs a graphics demo chosen at random.  It
       turns off as soon as there is any mouse or keyboard activity.

       This program can lock your terminal in order  to  prevent  others  from
       using  it,  though  its  default mode of operation is merely to display
       pretty pictures on your screen when it is not in use.

       It also provides configuration and control  of  your  monitor’s  power-
       saving features.

GETTING STARTED

       For the impatient, try this:

            xscreensaver &
            xscreensaver-demo

       The  xscreensaver-demo(1)  program  pops  up a dialog box that lets you
       configure the screen saver, and experiment  with  the  various  display
       modes.

       Note:  unlike  xlock(1),  xscreensaver  has  a client-server model: the
       xscreensaver program is a daemon that runs in  the  background;  it  is
       controlled  by  the  foreground  xscreensaver-demo(1) and xscreensaver-
       command(1) programs.

CONFIGURATION

       The easiest  way  to  configure  xscreensaver  is  to  simply  run  the
       xscreensaver-demo(1)  program, and change the settings through the GUI.
       The rest of this manual page describes lower  level  ways  of  changing
       settings.

       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 paramter in the
       .xscreensaver file, you would write the following:

            timeout: 5

       whereas, in the .Xdefaults file, you would write

            xscreensaver.timeout: 5

       If you change a setting in the .xscreensaver file while xscreensaver is
       already  running,  it will notice this, and reload the file.  (The file
       will be reloaded the next time the screen  saver  needs  to  take  some
       action,  such  as  blanking  or unblanking the screen, or picking a new
       graphics mode.)

       If you change a setting in your X resource database,  or  if  you  want
       xscreensaver  to  notice  your  changes immediately instead of the next
       time it wakes up, then you will need to reload  your  .Xdefaults  file,
       and  then tell the running xscreensaver process to restart itself, like
       so:

            xrdb < ~/.Xdefaults
            xscreensaver-command -restart

       If you want to set the system-wide defaults, then make  your  edits  to
       the  xscreensaver  app-defaults  file, which should have been installed
       when xscreensaver itself was installed.   The  app-defaults  file  will
       usually  be named /usr/lib/X11/app-defaults/XScreenSaver, but different
       systems  might  keep  it   in   a   different   place   (for   example,
       /usr/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.)

       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  xdm(1)
               because  it  can’t know the user-id of the logged-in user.  See
               the ‘‘Using XDM(1)’’ section, below.

       lockTimeout (class Time)
               If locking is enabled, this controls the length of the  ‘‘grace
               period’’  between  when the screensaver activates, and when the
               screen becomes locked.  For example, if this is 5, and -timeout
               is 10, then after 10 minutes, the screen would blank.  If there
               was user activity at 12 minutes, no password would be  required
               to  un-blank the screen.  But, if there was user activity at 15
               minutes  or  later  (that  is,  -lock-timeout   minutes   after
               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.

       visualID (class VisualID)
               Specify which X visual to use by default.  (Note carefully that
               this resource is called visualID, not merely visual; if you set
               the visual resource instead, things will malfunction in obscure
               ways for obscure reasons.)

               Legal values for the VisualID resource are:

               default Use the screen’s default visual (the visual of the root
                       window.)  This is the default.

               best    Use the visual which supports the most  colors.   Note,
                       however,  that the visual with the most colors might be
                       a TrueColor visual, which  does  not  support  colormap
                       animation.    Some   programs   have  more  interesting
                       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.

               number  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, below.

       installColormap (class Boolean)
               On  PseudoColor  (8-bit)  displays,  install a private colormap
               while the screensaver is active, so that the graphics hacks can
               get  as  many  colors as possible.  This is the default.  (This
               only applies when the screen’s default visual  is  being  used,
               since    non-default    visuals   get   their   own   colormaps
               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.

       quad (class Boolean)
               If  true,  then  four screensavers will be run on each monitor.
               Use at your own risk!

       helpURL (class URL)
               The splash screen has a Help button on it.  When you press  it,
               it  will  display  the  web  page  indicated  here  in your web
               browser.

       loadURL (class LoadURL)
               This is the shell command used to load  a  URL  into  your  web
               browser.     The    default   setting   will   load   it   into
               Mozilla/Netscape if it  is  already  running,  otherwise,  will
               launch a new browser looking at the helpURL.

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

       prefsCommand (class PrefsCommand)
               This  is  the  shell  command  run when the Prefs button on the
               splash    window    is     pressed.      It     defaults     to
               xscreensaver-demo -prefs.

       nice (class Nice)
               The  sub-processes created by xscreensaver will be ‘‘niced’’ to
               this level, so that they are given lower  priority  than  other
               processes   on   the   system,  and  don’t  increase  the  load
               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.   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  xscreensaver-demo(1)  program
               will  suppress  the non-existent programs from the list if this
               is true.  Default: false.

       GetViewPortIsFullOfLies (class Boolean)
               Set this to true if the xscreensaver window doesn’t  cover  the
               whole  screen.   This  works  around a longstanding XFree86 bug
               #421.  See the xscreensaver FAQ for details.

       font (class Font)
               The font used for the stdout/stderr text, if  captureStderr  is
               true.   Default  *-medium-r-*-140-*-m-* (a 14 point fixed-width
               font.)

       mode (class Mode)
               Controls the behavior of xscreensaver.  Legal values are:

               random  When blanking the screen, select a random display  mode
                       from among those that are enabled and applicable.  This
                       is the default.

               random-same
                       Like random, but if there are  multiple  screens,  each
                       screen  will  run the same random display mode, instead
                       of each screen running a different one.

               one     When blanking the screen, only ever use one  particular
                       display   mode  (the  one  indicated  by  the  selected
                       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-demo(1)  do  it  for
               you!

       programs (class Programs)
               The  graphics  hacks  which  xscreensaver runs when the user is
               idle.  The value of this resource is a multi-line  string,  one
               sh-syntax command per line.  Each line must contain exactly one
               command: no semicolons, no ampersands.

               When the screensaver  starts  up,  one  of  these  is  selected
               (according  to  the  mode  setting),  and run.  After the cycle
               period expires, it is killed, and another is selected and  run.

               If  a  line begins with a dash (-) then that particular program
               is disabled: it won’t be selected at  random  (though  you  can
               still  select  it  explicitly  using  the  xscreensaver-demo(1)
               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

               Make sure your $PATH environment variable is set  up  correctly
               before  xscreensaver  is  launched, or it won’t be able to find
               the programs listed in the programs resource.

               To use a program as a screensaver,  two  things  are  required:
               that  that  program  draw  on the root window (or be able to be
               configured to draw on the root window); and that  that  program
               understand  ‘‘virtual root’’ windows, as used by virtual window
               managers such as tvtwm(1).  (Generally, this is accomplished by
               just  including  the  "vroot.h"  header  file  in the program’s
               source.)

               If there are some programs that you want to run only when using
               a  color  display,  and  others  that you want to run only when
               using a monochrome display, you can specify that like this:

                           mono:   mono-program  -root        \n\
                           color:  color-program -root        \n\

               More generally, you can specify the kind of visual that  should
               be  used  for  the window on which the program will be drawing.
               For example, if one program works best if it  has  a  colormap,
               but  another  works best if it has a 24-bit visual, both can be
               accommodated:

                           PseudoColor: cmap-program  -root   \n\
                           TrueColor:   24bit-program -root   \n\

               In addition to the symbolic visual names  described  above  (in
               the  discussion of the visualID resource) one other visual name
               is supported in the programs list:

                default-n
                    This is like default, but also requests  the  use  of  the
                    default  colormap,  instead  of a private colormap.  (That
                    is, it behaves as if the -no-install  command-line  option
                    was  specified,  but only for this particular hack.)  This
                    is provided because some third-party programs that draw on
                    the  root  window  (notably:  xv(1),  and  xearth(1)) make
                    assumptions about the visual  and  colormap  of  the  root
                    window: assumptions which xscreensaver can violate.

               If  you  specify  a  particular  visual for a program, and that
               visual does not exist on the screen, then that program will not
               be  chosen  to  run.  This means that on displays with multiple
               screens of different depths, you can  arrange  for  appropriate
               hacks  to  be run on each.  For example, if one screen is color
               and the other is monochrome, hacks that look good in  mono  can
               be run on one, and hacks that only look good in color will show
               up on the other.

       You shouldn’t ever need to change the following resources:

       pointerPollTime (class Time)
               When server extensions  are  not  in  use,  this  controls  how
               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...)

       There are a number of different X  server  extensions  which  can  make
       xscreensaver’s  job  easier.   The  next  few resources specify whether
       these extensions should be utilized if they are available.

       sgiSaverExtension (class Boolean)
               This resource controls  whether  the  SGI  SCREEN_SAVER  server
               extension  will  be  used  to  decide whether the user is idle.
               This is the default if  xscreensaver  has  been  compiled  with
               support  for  this  extension  (which  is  the  default  on SGI
               systems.).  If it is  available,  the  SCREEN_SAVER  method  is
               faster  and  more reliable than what will be done otherwise, so
               use it if you  can.   (This  extension  is  only  available  on
               Silicon Graphics systems, unfortunately.)

       mitSaverExtension (class Boolean)
               This  resource  controls  whether  the  MIT-SCREEN-SAVER server
               extension will be used to decide  whether  the  user  is  idle.
               However,  the  default for this resource is false, because even
               if this extension is available, it is flaky (and it also  makes
               the  fade  option not work properly.)  Use of this extension is
               strongly discouraged.  Support for it will probably be  removed
               eventually.

       xidleExtension (class Boolean)
               This  resource controls whether the XIDLE server extension will
               be used to decide whether  the  user  is  idle.   This  is  the
               default if xscreensaver has been compiled with support for this
               extension.  (This extension is only  available  for  X11R4  and
               X11R5 systems, unfortunately.)

       procInterrupts (class Boolean)
               This resource controls whether the /proc/interrupts file should
               be consulted to decide whether the user is idle.  This  is  the
               default  if  xscreensaver  has  been compiled on a system which
               supports this mechanism (i.e., Linux systems.)

               The benefit to doing this is that xscreensaver  can  note  that
               the  user  is  active even when the X console is not the active
               one:  if  the  user  is  typing  in  another  virtual  console,
               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.

COMMAND-LINE OPTIONS

       xscreensaver  also  accepts  a few command-line options, mostly for use
       when debugging: for normal operation, you should configure  things  via
       the ~/.xscreensaver file.

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

       -verbose
               Same as setting the verbose resource to true: print diagnostics
               on stderr and on the xscreensaver window.

       -no-capture-stderr
               Same as setting the captureStderr resource  to  false:  do  not
               redirect  the  stdout  and  stderr  streams to the xscreensaver
               window itself.  If xscreensaver is crashing, you might need  to
               do this in order to see the error message.

HOW IT WORKS

       When it is time to activate the screensaver, a full-screen black window
       is created on each screen of the display.  Each window  is  created  in
       such  a  way that, to any subsequently-created programs, it will appear
       to be a ‘‘virtual root’’ window.  Because of this,  any  program  which
       draws  on  the root window (and which understands virtual roots) can be
       used as a screensaver.

       When the  user  becomes  active  again,  the  screensaver  windows  are
       unmapped,  and  the  running  subprocesses  are  killed by sending them
       SIGTERM.  This is  also  how  the  subprocesses  are  killed  when  the
       screensaver decides that it’s time to run a different demo: the old one
       is killed and a new one is launched.

       Before launching a subprocess, xscreensaver stores an appropriate value
       for  $DISPLAY in the environment that the child will receive.  (This is
       so that if  you  start  xscreensaver  with  a  -display  argument,  the
       programs which xscreensaver launches will draw on the same display; and
       so that the child will end up drawing on the appropriate  screen  of  a
       multi-headed display.)

       When  the screensaver turns off, or is killed, care is taken to restore
       the ‘‘real’’ virtual root window if there is one.  Because of this,  it
       is  important that you not kill the screensaver process with kill -9 if
       you are running a virtual-root window manager.  If you kill it with -9,
       you may need to restart your window manager to repair the damage.  This
       isn’t an issue if you aren’t running a virtual-root window manager.

       For  all  the  gory  details,  see  the  commentary  at  the   top   of
       xscreensaver.c.

       You   can   control   a   running  screensaver  process  by  using  the
       xscreensaver-command(1) program (which see.)

POWER MANAGEMENT

       Modern X servers contain support to power down  the  monitor  after  an
       idle  period.   If the monitor has powered down, then xscreensaver will
       notice this (after a few minutes), and will not waste  CPU  by  drawing
       graphics  demos  on  a  black  screen.  An attempt will also be made to
       explicitly power the monitor back  up  as  soon  as  user  activity  is
       detected.

       As  of  version  3.28 (Feb 2001), the ~/.xscreensaver file controls the
       configuration of your display’s power management settings: if you  have
       used   xset(1)   to   change   your  power  management  settings,  then
       xscreensaver will override those changes with the values  specified  in
       ~/.xscreensaver  (or  with  its  built-in  defaults,  if  there  is  no
       ~/.xscreensaver file yet.)

       To change your power management settings, run xscreensaver-demo(1)  and
       change  the  various timeouts through the user interface.  Alternately,
       you can edit the ~/.xscreensaver file directly.

       If   the   power   management   section   is   grayed   out   in    the
       xscreensaver-demo(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.

       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  XF86Config(5)
       manual for details.

USING XDM(1)

       You  can  run  xscreensaver  from  your  xdm(1)  session,  so  that the
       screensaver will run even when nobody is logged in on the console.

       The trick to using xscreensaver with xdm is this: keep in mind the  two
       very different states in which xscreensaver will be running:

           1: Nobody logged in.

              If you’re thinking of running xscreensaver from XDM at all, then
              it’s probably because you want graphics demos to be  running  on
              the  console  when  nobody  is  logged  in there.  In this case,
              xscreensaver will function only as a screen saver, not a  screen
              locker:  it  doesn’t  make  sense  for  xscreensaver to lock the
              screen, since nobody is logged in yet!  The only  thing  on  the
              screen is the XDM login prompt.

           2: Somebody logged in.

              Once  someone  has  logged  in through the XDM login window, the
              situation is very different.  For example: now it makes sense to
              lock  the screen (and prompt for the logged in user’s password);
              and now xscreensaver should consult that user’s  ~/.xscreensaver
              file; and so on.

       The  difference  between  these two states comes down to a question of,
       which user is the xscreensaver  process  running  as?   For  the  first
       state,  it  doesn’t matter.  If you start xscreensaver in the usual XDM
       way, then xscreensaver will probably end up running as root,  which  is
       fine for the first case (the ‘‘nobody logged in’’ case.)

       However,  once someone is logged in, running as root is no longer fine:
       because xscreensaver  will  be  consulting  root’s  .xscreensaver  file
       instead  of  that of the logged in user, and won’t be prompting for the
       logged in user’s password, and so on.  (This is not a security problem,
       it’s just not what you want.)

       So,  once someone has logged in, you want xscreensaver to be running as
       that user.  The way to accomplish this is to kill the old  xscreensaver
       process and start a new one (as the new user.)

       The simplest way to accomplish all of this is as follows:

           1: Launch xscreensaver before anyone logs in.

              To the file /usr/lib/X11/xdm/Xsetup, add the lines

                   xhost +localhost
                   xscreensaver-command -exit
                   xscreensaver &

              This  will  run xscreensaver as root, over the XDM login window.
              Moving the mouse will cause the screen to  un-blank,  and  allow
              the user to type their password at XDM to log in.

           2: Restart xscreensaver when someone logs in.

              Near  the  top  of the file /usr/lib/X11/xdm/Xsession, add those
              same lines:

                   xscreensaver-command -exit
                   xscreensaver &

              When someone logs in, this will kill  off  the  existing  (root)
              xscreensaver  process,  and start a new one, running as the user
              who has just  logged  in.   If  the  user’s  .xscreensaver  file
              requests  locking, they’ll get it.  They will also get their own
              choice of timeouts, and graphics demos, and so on.

              Alternately, each user could  just  put  those  lines  in  their
              personal ~/.xsession files.

       Make  sure  you  have $PATH set up correctly in the Xsetup and Xsession
       scripts, or xdm won’t be able to find xscreensaver, and/or xscreensaver
       won’t be able to find its graphics demos.

       (If  your system does not seem to be executing the Xsetup file, you may
       need to configure it to do so: the traditional way to  do  this  is  to
       make  that  file  the value of the DisplayManager*setup resource in the
       /usr/lib/X11/xdm/xdm-config file.  See the man page for xdm(1) for more
       details.)

       It  is  safe  to run xscreensaver as root (as xdm is likely to do.)  If
       run as root, xscreensaver changes its effective user and group  ids  to
       something  safe  (like  "nobody")  before connecting to the X server or
       launching user-specified programs.

       An unfortunate side effect of this (important) security  precaution  is
       that it may conflict with cookie-based authentication.

       If  you  get "connection refused" errors when running xscreensaver from
       xdm, then this probably means that you  have  xauth(1)  or  some  other
       security   mechanism  turned  on.   One  way  around  this  is  to  add
       "xhost +localhost" to Xsetup, just before xscreensaver is launched.

       Note that this will give access to the X server to  anyone  capable  of
       logging  in  to  the local machine, so in some environments, this might
       not be appropriate.  If turning off file-system-based access control is
       not  acceptable,  then  running xscreensaver from the Xsetup file might
       not be possible, and xscreensaver will only  work  when  running  as  a
       normal, unprivileged user.

       For  more  information on the X server’s access control mechanisms, see
       the man pages for X(1), Xsecurity(1), xauth(1), and xhost(1).

USING GDM(1)

       Using xscreensaver with gdm(1) is easy, because gdm has a configuration
       tool.   Just  fire  up  gdmconfig(1)  and  on the Background page, type
       "xscreensaver -nosplash" into the Background Program field.  That  will
       cause gdm to run xscreensaver while nobody is logged in, and kill it as
       soon as someone does log in.  (The user will then  be  responsible  for
       starting xscreensaver on their own, if they want.)

       Another  way  to  accomplish  the  same  thing  is  to  edit  the  file
       /etc/X11/gdm/gdm.conf to include:

            BackgroundProgram=xscreensaver -nosplash
            RunBackgroundProgramAlways=true

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

       To get gdm to run the BackgroundProgram, you may need to switch it from
       the "Graphical Greeter" to the "Standard Greeter".

USING KDE (K DESKTOP ENVIRONMENT)

       I  understand  that  KDE  has  invented  their   own   wrapper   around
       xscreensaver, that is inferior to xscreensaver-demo(1) in any number of
       ways.  I’ve never actually seen it, but I’m told that this is  the  way
       you disable it:

           1: Switch off KDEs screen saver.
              Open the ‘‘Control Center’’ and select the ‘‘Appearance & Themes
              -> Screensaver’’ page.  Turn  off  the  ‘‘Start  Automatically’’
              checkbox.

           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.
              Replace   the   file   /usr/bin/kdesktop_lock    (or    possibly
              /usr/kde/3.5/bin/kdesktop_lock) with these two lines:

                   #!/bin/sh
                   xscreensaver-command -lock

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

       Now   use   xscreensaver   normally,   controlling  it  via  the  usual
       xscreensaver-demo(1) and xscreensaver-command(1) mechanisms.

USING CDE (COMMON DESKTOP ENVIRONMENT)

       The easiest way to use xscreensaver on a system with CDE is  to  simply
       switch  off the built-in CDE screensaver, and use xscreensaver instead;
       and second, to tell the front panel to run xscreensaver-command(1) with
       the -lock option when the Lock icon is clicked.

       To accomplish this involves five steps:

           1: Switch off CDEs locker
              Do  this  by turning off ‘‘Screen Saver and Screen Lock’’ in the
              Screen section of the Style Manager.

           2: Edit sessionetc
              Edit the file ~/.dt/sessions/sessionetc and add to it the line

                   xscreensaver &

              And make sure the sessionetc  file  is  executable.   This  will
              cause  xscreensaver to be launched when you log in.  (As always,
              make sure that xscreensaver and the graphics demos are  on  your
              $PATH; the path needs to be set in .cshrc and/or .dtprofile, not
              .login.)

           3: Create XScreenSaver.dt
              Create  a  file  called  ~/.dt/types/XScreenSaver.dt  with   the
              following contents:

                   ACTION XScreenSaver
                   {
                     LABEL         XScreenSaver
                     TYPE          COMMAND
                     EXEC_STRING   xscreensaver-command -lock
                     ICON          Dtkey
                     WINDOW_TYPE   NO_STDIO
                   }

              This  defines  a  ‘‘lock’’ command for the CDE front panel, that
              knows how to talk to xscreensaver.

           4: Create Lock.fp
              Create a file  called  ~/.dt/types/Lock.fp  with  the  following
              contents:

                   CONTROL Lock
                   {
                     TYPE             icon
                     CONTAINER_NAME   Switch
                     CONTAINER_TYPE   SWITCH
                     POSITION_HINTS   1
                     ICON             Fplock
                     LABEL            Lock
                     PUSH_ACTION      XScreenSaver
                     HELP_TOPIC       FPOnItemLock
                     HELP_VOLUME      FPanel
                   }

              This  associates the CDE front panel ‘‘Lock’’ icon with the lock
              command we just defined in step 3.

           5: Restart
              Select ‘‘Restart Workspace Manager’’ from the popup menu to make
              your  changes  take  effect.   If things seem not to be working,
              check the file ~/.dt/errorlog for error messages.

USING HP VUE (VISUAL USER ENVIRONMENT)

       Since  CDE  is  a  descendant  of  VUE,  the  instructions  for   using
       xscreensaver under VUE are similar to the above:

           1: Switch off VUEs locker
              Open  the  ‘‘Style  Manager’’  and  select ‘‘Screen.’’  Turn off
              ‘‘Screen Saver and Screen Lock’’ option.

           2: Make sure you have a Session
              Next, go to the Style Manager’s,  ‘‘Startup’’  page.   Click  on
              ‘‘Set  Home  Session’’  to create a session, then on ‘‘Return to
              Home Session’’ to select this session each time you log in.

           3: Edit vue.session
              Edit the file ~/.vue/sessions/home/vue.session and add to it the
              line

                   vuesmcmd -screen 0 -cmd "xscreensaver"

              This  will  cause  xscreensaver  to be launched when you log in.
              (As always, make sure that xscreensaver and the  graphics  demos
              are  on  your  $PATH;  the path needs to be set in .cshrc and/or
              .profile, not .login.)

           3: Edit vuewmrc
              Edit the file  ~/.vue/vuewmrc  and  add  (or  change)  the  Lock
              control:

                   CONTROL Lock
                   {
                     TYPE         button
                     IMAGE        lock
                     PUSH_ACTION  f.exec "xscreensaver-command -lock"
                     HELP_TOPIC   FPLock
                   }

              This  associates  the  VUE  front  panel  ‘‘Lock’’ icon with the
              xscreensaver lock command.

BUGS

       Bugs?  There are no bugs.  Ok, well, maybe.  If you  find  one,  please
       let me know.  http://www.jwz.org/xscreensaver/bugs.html explains how to
       construct the most useful bug reports.

       Locking and XDM
               If xscreensaver has been launched from xdm(1) before anyone has
               logged  in,  you  will  need  to  kill  and  then  restart  the
               xscreensaver daemon after you have logged in, or  you  will  be
               confused by the results.  (For example, locking won’t work, and
               your ~/.xscreensaver file will be ignored.)

               When you are logged in, you want the xscreensaver daemon to  be
               running under your user id, not as root or some other user.

               If  it  has  already  been  started  by xdm, you can kill it by
               sending it the exit command, and then re-launching it  as  you,
               by  putting  something  like  the  following in your personal X
               startup script:

                    xscreensaver-command -exit
                    xscreensaver &

               The ‘‘Using XDM(1)’’ section, above, goes into more detail, and
               explains  how  to configure the system to do this for all users
               automatically.

       Locking and root logins
               In order for it to be safe for xscreensaver to be  launched  by
               xdm,  certain  precautions  had  to  be  taken, among them that
               xscreensaver never runs as  root.   In  particular,  if  it  is
               launched  as  root  (as xdm is likely to do), xscreensaver will
               disavow its privileges, and switch itself to  a  safe  user  id
               (such as nobody.)

               An  implication  of  this  is that if you log in as root on the
               console, xscreensaver will refuse to lock the  screen  (because
               it  can’t  tell  the difference between root being logged in on
               the console, and a normal user being logged in on  the  console
               but  xscreensaver  having  been  launched  by the xdm(1) Xsetup
               file.)

               The solution to this is simple: you shouldn’t be logging in  on
               the  console  as root in the first place!  (What, are you crazy
               or something?)

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

       XAUTH and XDM
               For xscreensaver to work  when  launched  by  xdm(1),  programs
               running  on  the local machine as user "nobody" must be able to
               connect to the X server.  This means that if you  want  to  run
               xscreensaver  on the console while nobody is logged in, you may
               need to disable cookie-based  access  control  (and  allow  all
               users  who  can  log  in to the local machine to connect to the
               display.)

               You should be sure that this is an acceptable thing  to  do  in
               your  environment  before  doing  it.  See the ‘‘Using XDM(1)’’
               section, above, for more details.

       Passwords
               If you get an error message  at  startup  like  ‘‘couldn’t  get
               password  of  user’’  then this probably means that you’re on a
               system in which the getpwent(3) library  routine  can  only  be
               effectively   used   by  root.   If  this  is  the  case,  then
               xscreensaver must be installed as setuid to root in  order  for
               locking to work.  Care has been taken to make this a safe thing
               to do.

               It also may mean that your system uses shadow passwords instead
               of  the  standard  getpwent(3) interface; in that case, you may
               need to change some options with configure and recompile.

               If  you  change  your  password  after  xscreensaver  has  been
               launched,  it  will  continue using your old password to unlock
               the screen until xscreensaver is restarted.  On  some  systems,
               it  may  accept both your old and new passwords.  So, after you
               change your password, you’ll have to do

                    xscreensaver-command -restart

               to make xscreensaver notice.

       PAM Passwords
               If your system uses  PAM  (Pluggable  Authentication  Modules),
               then in order for xscreensaver to use PAM properly, PAM must be
               told about xscreensaver.  The xscreensaver installation process
               should  update  the  PAM  data  (on Linux, by creating the file
               /etc/pam.d/xscreensaver for you, and on Solaris, by telling you
               what lines to add to the /etc/pam.conf file.)

               If  the PAM configuration files do not know about xscreensaver,
               then you might be in a situation where xscreensaver will refuse
               to ever unlock the screen.

               This  is  a design flaw in PAM (there is no way for a client to
               tell the difference between PAM responding ‘‘I have never heard
               of  your  module,’’  and  responding,  ‘‘you  typed  the  wrong
               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!

       Colormap lossage: TWM
               The  installColormap  option  doesn’t  work  very well with the
               twm(1) window manager and its descendants, on 8-bit screens.

               There is a race condition  between  the  screensaver  and  this
               window  manager, which can result in the screensaver’s colormap
               not getting installed properly, meaning the graphics hacks will
               appear in essentially random colors.  (If the screen goes white
               instead of black, this is probably why.)

               The mwm(1) and olwm(1) window managers don’t have this problem.
               The  race  condition  exists because X (really, ICCCM) does not
               provide a way for an OverrideRedirect window to  have  its  own
               colormap, short of grabbing the server (which is neither a good
               idea, nor really  possible  with  the  current  design.)   What
               happens is that, as soon as xscreensaver installs its colormap,
               twm responds to  the  resultant  ColormapNotify  event  by  re-
               installing  the  default  colormap.   Apparently,  twm  doesn’t
               always do this; it seems to do it regularly if the  screensaver
               is  activated  from  a menu item, but seems to not do it if the
               screensaver comes on of its own volition, or is activated  from
               another console.

               Attention, window manager authors!
                   You  should  only  call  XInstallColormap(3) in response to
                   user events.  That is,  it  is  appropriate  to  install  a
                   colormap in response to FocusIn, FocusOut, EnterNotify, and
                   LeaveNotify events; but it is not appropriate to call it in
                   response   to   ColormapNotify   events.   If  you  install
                   colormaps in response to application actions as well as  in
                   response  to  user  actions,  then you create the situation
                   where it is impossible for  override-redirect  applications
                   (such  as  xscreensaver)  to  display  their windows in the
                   proper colors.

       Colormap lossage: XV, XAnim, XEarth
               Some programs don’t operate properly on visuals other than  the
               default one, or with colormaps other than the default one.  See
               the discussion of the magic  "default-n"  visual  name  in  the
               description  of  the  programs  resource  in  the Configuration
               section.  When programs only work with  the  default  colormap,
               you need to use a syntax like this:

                       default-n: xv -root image-1.gif -quit  \n\
                       default-n: xearth -nostars -wait 0     \n\

               It  would  also  work  to  turn  off the installColormap option
               altogether, but that would deny extra colors to those  programs
               that can take advantage of them.

       Machine Load
               Although  this  program  ‘‘nices’’  the  subprocesses  that  it
               starts, graphics-intensive subprograms can still  overload  the
               machine  by  causing  the X server process itself (which is not
               ‘‘niced’’) to consume many cycles.  Care has been taken in  all
               the  modules  shipped  with xscreensaver to sleep periodically,
               and not run full tilt, so as not to cause appreciable load.

               However, if you are running the OpenGL-based screen savers on a
               machine  that  does not have a video card with 3D acceleration,
               they will make your machine slow, despite nice(1).

               Your options are: don’t  use  the  OpenGL  display  modes;  or,
               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.)

       XFree86s 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 XF86Config(5) manual for details.

       MIT Extension and Fading
               The MIT-SCREEN-SAVER extension is junk.  Don’t use it.

               When  using  the MIT-SCREEN-SAVER extension in conjunction with
               the fade option, you’ll notice  an  unattractive  flicker  just
               before  the  fade  begins.   This  is because the server maps a
               black window just before it tells the xscreensaver  process  to
               activate.   The  xscreensaver  process  immediately unmaps that
               window, but this results in a flicker.  I haven’t figured a way
               to  get  around  this; it seems to be a fundamental property of
               the (mis-) design of this server extension.

               It sure would be  nice  if  someone  would  implement  the  SGI
               SCREEN_SAVER  extension in XFree86; it’s dead simple, and works
               far better than the over-engineered and broken MIT-SCREEN-SAVER
               extension.

       Keyboard LEDs
               If procInterrupts is on (which is the default on Linux systems)
               and you’re using some program that toggles the  state  of  your
               keyboard  LEDs,  xscreensaver  won’t  work right: turning those
               LEDs on or off causes a keyboard interrupt, which  xscreensaver
               will  interpret  as  user  activity.  So if you’re using such a
               program, set the procInterrupts resource to False.

       Extensions
               If you are not making use  of  one  of  the  server  extensions
               (XIDLE,  SGI  SCREEN_SAVER,  or  MIT-SCREEN-SAVER),  then it is
               possible, in rare situations,  for  xscreensaver  to  interfere
               with  event propagation and make another X program malfunction.
               For this to occur, that other application  would  need  to  not
               select KeyPress events on its non-leaf windows within the first
               30 seconds of their existence, but then select for them  later.
               In  this  case, that client might fail to receive those events.
               This isn’t very  likely,  since  programs  generally  select  a
               constant set of events immediately after creating their windows
               and then don’t change them, but this is the reason that it’s  a
               good  idea  to  install  and  use  one of the server extensions
               instead, to work around this shortcoming in the X protocol.

               In all these years, I’ve not heard of even  a  single  case  of
               this  happening,  but  it  is  theoretically  possible,  so I’m
               mentioning it for completeness...

ENVIRONMENT

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

       PATH    to find the sub-programs to run.

       HOME    for the directory in which to read the .xscreensaver file.

       XENVIRONMENT
               to  get  the  name of a resource file that overrides the global
               resources stored in the RESOURCE_MANAGER property.

UPGRADES

       The latest version of xscreensaver, an online version of  this  manual,
       and a FAQ can always be found at http://www.jwz.org/xscreensaver/

SEE ALSO

       X(1),     Xsecurity(1),    xauth(1),    xdm(1),    gdm(1),    xhost(1),
       xscreensaver-demo(1),                          xscreensaver-command(1),
       xscreensaver-gl-helper(1),                    xscreensaver-getimage(1),
       xscreensaver-text(1).

COPYRIGHT

       Copyright © 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
       2001,  2002,  2003,  2004,  2005 by Jamie Zawinski.  Permission to use,
       copy, modify, distribute, and sell this software and its  documentation
       for  any purpose is hereby granted without fee, provided that the above
       copyright notice appear in all copies  and  that  both  that  copyright
       notice  and  this permission notice appear in supporting documentation.
       No representations are made about the suitability of this software  for
       any  purpose.   It  is  provided  "as  is"  without  express or implied
       warranty.

AUTHOR

       Jamie Zawinski <jwz@jwz.org>.  Written in late 1991; version 1.0 posted
       to comp.sources.x on 17-Aug-1992.

       Please let me know if you find any bugs or make any improvements.

ACKNOWLEDGEMENTS

       Thanks to Angela Goodman for the XScreenSaver logo.

       Thanks  to  the  many people who have contributed graphics demos to the
       package.

       Thanks to David Wojtowicz for implementing lockTimeout.

       Thanks to Martin Kraemer for adding support for  shadow  passwords  and
       locking-disabled diagnostics.

       Thanks to Patrick Moreau for the VMS port.

       Thanks to Nat Lanza for the Kerberos support.

       Thanks to Bill Nottingham for the initial PAM support.

       And  thanks  to  Jon  A. Christopher for implementing the Athena dialog
       support,  back  in  the  days  before  Lesstif  or  Gtk   were   viable
       alternatives to Motif.