Where Is the core-site.xml File in a Hadoop Installation?

Problem scenario
You downloaded and installed Hadoop core (an open source version). But you cannot find the core-site.xml file. (This is for open source Hadoop -- not a proprietary version.) What should you do?

Possible Solution #1
Run this:

sudo find / -name core-site.xml

Possible Solution #2
Did you download the installation media with a file "-site" in its name?

Try again with a .tar.gz file without "-site" (and without "-src") in its name:
https://dlcdn.apache.org/hadoop/core/stable/