Provided by: xscreensaver_5.42+dfsg1-1ubuntu1_amd64 
NAME
xscreensaver-command - control a running xscreensaver process
SYNOPSIS
xscreensaver-command [-display host:display.screen] [-help | -demo | -prefs | -activate | -deactivate |
-cycle | -next | -prev | -select n | -exit | -restart | -lock | -version | -time | -watch]
DESCRIPTION
The xscreensaver-command program controls a running xscreensaver process by sending it client-messages.
xscreensaver(1) has a client-server model: the xscreensaver process is a daemon that runs in the
background; it is controlled by other foreground programs such as xscreensaver-command and
xscreensaver-demo(1).
This program, xscreensaver-command, is a command-line-oriented tool; the xscreensaver-demo(1). program
is a graphical tool.
OPTIONS
xscreensaver-command accepts the following command-line options:
-help Prints a brief summary of command-line options.
-demo This just launches the xscreensaver-demo(1) program, in which one can experiment with the various
graphics hacks available, and edit parameters.
-demo number
When the -demo option is followed by an integer, it instructs the xscreensaver daemon to run that
hack, and wait for the user to click the mouse before deactivating (i.e., mouse motion does not
deactivate.) This is the mechanism by which xscreensaver-demo(1) communicates with the
xscreensaver(1) daemon. (The first hack in the list is numbered 1, not 0.)
-prefs Like the no-argument form of -demo, but brings up that program's Preferences panel by default.
-activate
Tell xscreensaver to turn on immediately (that is, blank the screen, as if the user had been idle
for long enough.) The screensaver will deactivate as soon as there is any user activity, as
usual.
It is useful to run this from a menu; you may wish to run it as
sleep 5 ; xscreensaver-command -activate
to be sure that you have time to take your hand off the mouse before the screensaver comes on.
(Because if you jiggle the mouse, xscreensaver will notice, and deactivate.)
-deactivate
This tells xscreensaver to pretend that there has just been user activity. This means that if
the screensaver is active (the screen is blanked), then this command will cause the screen to un-
blank as if there had been keyboard or mouse activity. If the screen is locked, then the
password dialog will pop up first, as usual. If the screen is not blanked, then this simulated
user activity will re-start the countdown (so, issuing the -deactivate command periodically is
one way to prevent the screen from blanking.)
-cycle If the screensaver is active (the screen is blanked), then stop the current graphics demo and run
a new one (chosen randomly.)
-next This is like either -activate or -cycle, depending on which is more appropriate, except that the
graphics hack that will be run is the next one in the list, instead of a randomly-chosen one. In
other words, repeatedly executing -next will cause the xscreensaver process to invoke each
graphics demo sequentially. (Though using the -demo option is probably an easier way to
accomplish that.)
-prev This is like -next, but cycles in the other direction.
-select number
Like -activate, but runs the Nth element in the list of hacks. By knowing what is in the
programs list, and in what order, you can use this to activate the screensaver with a particular
graphics demo. (The first element in the list is numbered 1, not 0.)
-exit Causes the xscreensaver process to exit gracefully. This does nothing if the display is
currently locked.
Warning: never use kill -9 with xscreensaver while the screensaver is active. If you are using a
virtual root window manager, that can leave things in an inconsistent state, and you may need to
restart your window manager to repair the damage.
-lock Tells the running xscreensaver process to lock the screen immediately. This is like -activate,
but forces locking as well, even if locking is not the default (that is, even if xscreensaver's
lock resource is false, and even if the lockTimeout resource is non-zero.)
Note that locking doesn't work unless the xscreensaver process is running as you. See
xscreensaver(1) for details.
-version
Prints the version of xscreensaver that is currently running on the display: that is, the actual
version number of the running xscreensaver background process, rather than the version number of
xscreensaver-command. (To see the version number of xscreensaver-command itself, use the -help
option.)
-time Prints the time at which the screensaver last activated or deactivated (roughly, how long the
user has been idle or non-idle: but not quite, since it only tells you when the screen became
blanked or un-blanked.)
-restart
Causes the screensaver process to exit and then restart with the same command line arguments as
last time. You shouldn't really need to do this, since xscreensaver notices when the
.xscreensaver file has changed and re-reads it as needed.
-watch Prints a line each time the screensaver changes state: when the screen blanks, locks, unblanks,
or when the running hack is changed. This option never returns; it is intended for use by shell
scripts that want to react to the screensaver in some way. An example of its output would be:
BLANK Fri Nov 5 01:57:22 1999
RUN 34
RUN 79
RUN 16
LOCK Fri Nov 5 01:57:22 1999
RUN 76
RUN 12
UNBLANK Fri Nov 5 02:05:59 1999
The above shows the screensaver activating, running three different hacks, then locking (perhaps
because the lock-timeout went off) then unblanking (because the user became active, and typed the
correct password.) The hack numbers are their index in the `programs' list (starting with 1, not
0, as for the -select command.)
For example, suppose you want to run a program that turns down the volume on your machine when
the screen blanks, and turns it back up when the screen un-blanks. You could do that by running
a Perl program like the following in the background. The following program tracks the output of
the -watch command and reacts accordingly:
#!/usr/bin/perl
my $blanked = 0;
open (IN, "xscreensaver-command -watch |");
while (<IN>) {
if (m/^(BLANK|LOCK)/) {
if (!$blanked) {
system "sound-off";
$blanked = 1;
}
} elsif (m/^UNBLANK/) {
system "sound-on";
$blanked = 0;
}
}
Note that LOCK might come either with or without a preceding BLANK (depending on whether the
lock-timeout is non-zero), so the above program keeps track of both of them.
STOPPING GRAPHICS
If xscreensaver is running, but you want it to stop running screen hacks (e.g., if you are logged in
remotely, and you want the console to remain locked but just be black, with no graphics processes
running) you can accomplish that by simply powering down the monitor remotely. In a minute or so,
xscreensaver will notice that the monitor is off, and will stop running screen hacks. You can power off
the monitor like so:
xset dpms force off
See the xset(1) manual for more info.
You can also use xscreensaver-demo(1) to make the monitor power down after a few hours, meaning that
xscreensaver will run graphics until it has been idle for the length of time you specified; and after
that, the monitor will power off, and screen hacks will stop being run.
DIAGNOSTICS
If an error occurs while communicating with the xscreensaver daemon, or if the daemon reports an error, a
diagnostic message will be printed to stderr, and xscreensaver-command will exit with a non-zero value.
If the command is accepted, an indication of this will be printed to stdout, and the exit value will be
zero.
ENVIRONMENT
DISPLAY to get the host and display number of the screen whose saver is to be manipulated.
PATH to find the executable to restart (for the -restart command). Note that this variable is
consulted in the environment of the xscreensaver process, not the xscreensaver-command process.
UPGRADES
The latest version of xscreensaver(1) and related tools can always be found at
https://www.jwz.org/xscreensaver/
SEE ALSO
X(1), xscreensaver(1), xscreensaver-demo(1), xset(1)
COPYRIGHT
Copyright © 1992-2013 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>, 13-aug-1992.
Please let me know if you find any bugs or make any improvements.