ubuntu:
git config --global merge.tool diffmerge
git config --global mergetool.diffmerge.cmd "/usr/bin/diffmerge --merge --result=\$MERGED \$LOCAL \$BASE \$REMOTE"
git config --global mergetool.keepBackup false
mac:
git config --global merge.tool diffmerge
git config --global mergetool.diffmerge.cmd "/Applications/DiffMerge.app/Contents/MacOS/diffmerge --merge --result=\$MERGED \$LOCAL \$BASE \$REMOTE"
git config --global mergetool.keepBackup false