Use KDiff3 in Mercurial

Firstly install KDiff3 by
>sudo apt-get install kdiff3

Then, add ~/.hgrc

[extensions]
hgext.extdiff =

[extdiff]
cmd.kdiff3 =

[merge-tools]
kdiff3.args = $base $local $other -o $output

Now it should work. Try
>hg kdiff3

Reference:

• http://mercurial.selenic.com/wiki/KDiff3