Recently, I was annoyed by the way my display went to sleep (power off/ stand-by mode) on Ubuntu / Linux. I have no screensaver installed so everything what happened was that after a few minutes of idling, the display would go to sleep (into stand by). But I had no means to speed this up, for example when I knew I'd be away for some time, this way, wasting a few minutes of power.
As it turns out, from command-line, you can issue the "go to sleep" command manually:
xset dpms force off
Now, on Ubuntu, you can easily define a custom Keyboard-Shortcut for this command:
Go to System > Keyboard > Shortcuts, and define / assocaited a new personal shortcut and enter "xset dpms force off" as the command. Then
define a keyboard shortcut for it to fire, for example I chose "CTRL" + "<" ...which happen to be next to each other on a QWERTZ keyboard.
... or switch your display off by clicking a desktop icon
Open terminal, and do this:
$ nano ~/Desktop/xoff.desktop
Paste this into the file:
Comment[en_EN]=switch off / turn off screen
Exec=xset dpms force off
Comment=switch off / turn off screen
and add the executable bit:
$ chmod ogw+x xoff.desktop
I found that firing the xset command, under certain circumstances which I don't understand, doesn't stick and is immediately overridden, so the screen lights up again right after going black. It could be that this happens with DRAW events on the X GUI canvas (as it's when some GUI application is doing animated updates), something like that.
Anyway, firing the xset command over and over seems to be the only solution. I was so annoyed by this, mashing the shortcut butoons until the screen remained asleep, that I wrote a small Perl script which I fire via the shortcut now, wrapping the xset command. And so far, this works great:
my $sleep = 0.3;
system("xset dpms force off");
# print "Fired xset, sleep $sleep \n";
$sleep += 0.2;