There are two keysyms for grave, grave and dead_grave, by default dead_grave is set to the ` key. xmodmap can be used to change it, and should be in Ubuntu by default (with arch install xorg-xmodmap).
To change it from the default dead_grave to grave, run:
xmodmap -e "keycode 49 = grave notsign grave notsign brokenbar notsign brokenbar notsign"
The rest of the values are various modifiers, e.g. the second one is shift.
If you want this to be permanent, create ~/.Xmodmap, and then add just:
keycode 49 = grave notsign grave notsign brokenbar notsign brokenbar notsign
If there are any other dead keys you're having trouble with, run:
xmodmap -pke | grep dead
And it should give you a list of dead keys. Alternatively you could run:
xmodmap -pke >> ~/.Xmodmap
You will then have a full list of keyboard keys and their sym values in .Xmodmap, which makes it easy to change your dead keys and any other keys to whatever custom layout you like.
xev -event keyboardand then press the key, what output do you get? – Seth May 13 '14 at 02:35