For some odd reason the Scroll Lock button doesn’t work in an Xsession in Ubuntu. There’s an old bug report here. However it works as it should in a virtual terminal.
The interesting thing though is that Xev will detect the key press. So how do you get the Scroll Lock functioning again? Well first let’s run this command
xmodmap -pm
You should get an output like this
xmodmap: up to 3 keys per modifier, (keycodes in parentheses):
shift Shift_L (0×32), Shift_R (0×3e)
lock Caps_Lock (0×42)
control Control_L (0×25), Control_R (0×6d)
mod1 Alt_L (0×40), Alt_L (0×7d), Meta_L (0×9c)
mod2 Num_Lock (0×4d)
mod3
mod4 Super_L (0×7f), Hyper_L (0×80)
mod5 Mode_switch (0×5d), ISO_Level3_Shift (0×7c)
Notice mod3 has nothing listed. This will be what we will use to assign Scroll Lock. It may be a different mod for some people. Either way use the one that has nothing listed.
Before we do anything else let’s test this to make sure it works. We’re going to run this command
xmodmap -e ‘add mod3 = Scroll_Lock’
Replace mod3 with whatever the blank mod listing was. Your Scroll Lock should work now.
I hate making changes like this locally to only my user, so I’m going to do this globally.
Now we need to create a file in /etc/X11 called Xmodmap. So start up Gedit or your favorite text editor
gksudo gedit /etc/X11/Xmodmap
Now add this to the file
add mod3 = Scroll_Lock
again, change mod3 to the one that was empty from the first command. Now the Scroll Lock key should get set when X starts now.

Very informative!
thanks man…i used this info go get my Trendnet KVM switch to work…it uses the key sequence “ScrLock + ScrLock” and my ubuntu wont recognize this…
for KVM use in Linux try use NumLock instead of ScrLock. But anyway better fix this
Thanks a lot, dude!
Thanks man !
What a strange bug! I also needed this for my KVM switch
Excellent info. I’ve used this in 8.04 to get my KVM working. I’ve recently upgraded to Intrepid Ibex 8.10, and it stopped working again. It appears that Xmodmap is no longer used and this must be taken care of though HAL. I’ve managed to do some tweaks to my mouse with a .fdi file. It looks like the same needs to be done to get scroll lock working again. How about an update here to show us noobs how it’s done?
Hey
Thanks for the info ! I have used it on a number of Ubuntu 8.04 boxes with success.
However if a make the mod in 9.04 it kills the alt-gr button. (The right alt key, which is frequently used on a danish keyboard layout as mine).
Does anyone know a workaround for this ?
I just upgraded to 9.10 and this will not work. is there a way to do this with newer versions or am SOL. also, i have been having problems with the flash plugins, i am not sure if this is just my hardware (which is very old) or if there is a known bug.