Best practices
From Impredicative Wiki
managing testing and live system
You don't want to edit your main .urp file for serving different deployments (testing, live) which differ in prefix and database setting only because the main .urp file is usually tracked by kind of version control system.
So you can split the main configuration from deployment specific settings by including the main config using "library"
testing.urp:
library main.urp database settings prefix ..
live.urp
library main.urp different database settings ...
Maybe you never want to commit testing.urp or live.urp but a template instead.
finding libraries no matter where they have been installed
reference libraries this way:
library $libraries/rel-path[/lib.urp]
Then use the -path option to tell urweb about where you put the libraries