Setting up the compose key to type accented characters

In /etc/X11/xorg.conf, in the keyboard section, I added the line:

Option   "XkbOptions" "compose:ralt"

Now, I can type most accented characters and umlauts by first hitting the right ALT key.

A few examples (key combinations below all preceded by right ALT key):

• ` e: è (backtick followed by e)
• " u: ü
• , c: ç
• s s: ß

Addendum

Changed this to the Caps Lock key with:

Option   "XkbOptions" "compose:caps"

in xorg.conf

Addendum 2

In Jaunty (and maybe since Intrepid), this no longer works. The update manager comments out the entire keyboard section in xorg.conf, with the comment:

# commented out by update-manager, HAL is now used

A temporary solution is to open a terminal and execute the command:

setxkbmap -option compose:caps

You’ll have to repeat this on each login. You could put this in a shell script and add that to the commands that get executed on startup.

Addendum 3

In Xubuntu Jaunty, you can edit the file /etc/default/console-setup to contain the line:

XKBOPTIONS="compose:caps"

to make this change permanent.

Thanks to foresto on the Ubuntu Forums!