Parabola package has a line like below in their PKGBUILD:
sed -i 's|google[.]com|duckduckgo.com/html|' data/defaults.khotkeys
It changes the line:
CommandURL=http://google.com
into:
CommandURL=http://duckduckgo.com/html
Converted it to a libre.patch
patch file with accompanying libre.patch.args
for storing patch parameters for it.