[diff]
	tool = diffmerge

[merge]
	tool = diffmerge

...

[mergetool "diffmerge"]
	cmd = /usr/local/bin/diffmerge --merge --result=\"$MERGED\" \"$LOCAL\" \"$BASE\" \"$REMOTE\"
	trustExitCode = true
[mergetool]
	keepBackup = false
[difftool "diffmerge"]
	cmd = /usr/local/bin/diffmerge --nosplash \"$LOCAL\" \"$REMOTE\"