XScreenSaver(1)XScreenSaver(1)NAMExscreensaver-command - control a running xscreensaver pro
cess
SYNOPSISxscreensaver-command [-display host:display.screen]
[-help] [-demo] [-prefs] [-activate] [-deactivate]
[-cycle] [-next] [-prev] [-select n] [-exit] [-restart]
[-lock] [-throttle] [-unthrottle] [-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 xscreen
saver 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-ori
ented tool; the xscreensaver-demo(1). program is a graph
ical tool.
OPTIONSxscreensaver-command accepts the following command-line
options:
-help Prints a brief summary of command-line options.
-demo This just launches the xscreensaver-demo(1) pro
gram, 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 pass
word 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 direc
tion.
-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 acti
vate 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 grace
fully. This is roughly the same as killing the
process with kill(1), but it is easier, since you
don't need to first figure out the pid.
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 xscreen_
saver process is running as you. See xscreen
saver(1) for details.
-throttle
Temporarily switch to ``blank screen'' mode, and
don't run any display modes at all, until the
screensaver is next de-activated. This is useful
if you're using a machine remotely, and you find
that some display modes are using too much CPU.
(If you want to do this permanently, that is, you
want the screen saver to only blank the screen and
not run demos at all, then set the programs
resource to an empty list: See xscreensaver(1)
for details.)
-unthrottle
Turn `-throttle' mode off and resume normal behav
ior.
-version
Prints the version of xscreensaver that is cur
rently running on the display: that is, the actual
version number of the running xscreensaver back
ground 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. Do this after you've changed the
resource database, to cause xscreensaver to notice
the changes.
Warning: if you have a .xscreensaver file, this
might not do what you expect. You're probably
better off killing the existing xscreensaver (with
xscreensaver-command -exit) and then launching it
again.
The important point is, you need to make sure that
the xscreensaver process is running as you. If
it's not, it won't be reading the right .xscreen_
saver file.
-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, run
ning 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
preceeding BLANK (depending on whether the lock-
timeout is non-zero), so the above program keeps
track of both of them.
DIAGNOSTICS
If an error occurs while communicating with the xscreen_
saver daemon, or if the daemon reports an error, a diag
nostic message will be printed to stderr, and xscreen_
saver-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 http://www.jwz.org/xscreensaver/
SEE ALSOX(1), xscreensaver(1)xscreensaver-demo(1)COPYRIGHT
Copyright 1992, 1993, 1997, 1998, 1999, 2000, 2001, 2002
by Jamie Zawinski. Permission to use, copy, modify, dis
tribute, 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-92.
Please let me know if you find any bugs or make any
improvements.
X Version 11 24-Feb-2002 (4.01) XScreenSaver(1)
