The problem I am having is, I'm trying to install the Houdini Engine Plugin into Unreal but Unreal doesn't know how to find Houdini. I looked through all the Unreal and Houdini Forums but they all point to Windows or MacOS solutions. This is the error I am getting.

Generating Make project files:
Generating data for project indexing...
Houdini Engine : Houdini 19.5.605 could not be found. Houdini Engine will not be available in this build.

I keep finding the same solution "set the $HFS environment variable to your houdini install folder" but where is this ie.. /path/to/file/or/folder?