How do I initialize and share .dll on Windows and .so on Linux?

You'll find out if you try, but it's a basic thing, so I'd like to ask you how it works.

Prerequisites

• Suppose you created a program with multiple modules in C++. Eventually, this program runs on the command line. The target operating systems are Windows and Linux.
• There are several submodules called from this main program. On Windows, they are built as .dll and on Linux as .so.
• Some submodules take values from environment variables and initialize their own static data. Values are abstract, so specifically, they are paths that contain fonts. So C:\Windows\Fonts is typical for Windows.
• On Windows, if you open two DOS windows and give them different environment variables and launch each command line for this main program, the static data in the .dll submodules will be initialized separately...because dll is not shared among processes.

What do you want to ask

However, I'm not sure what will happen to Linux's .so because I don't know enough. Linux's .so (Shared Object) seems to work as a mechanism for coexisting different versions of libraries, for example, as described below.

Shared Library

A shared library is a library that is loaded when a program starts. Once the shared library is properly installed, all subsequent programs will automatically use the new shared library. In fact, it's much more flexible and sophisticated than this, because the way Linux enables shared libraries to:

• You can update your library while still supporting programs that want to use older, non-backward compatible versions of that library.
• When you run a specific program, you can override a specific library or even a specific function in the library
• All of these can be done while the program is running using an existing library

However, if the same version of .so is loaded on the system by starting the main program that started in one terminal window, how does .so in this "submodule" that initializes itself by referring to the environment variable if you start the main program by giving a different terminal window?There are probably only two answers.

I would appreciate it if you could let me know what the above will be like above.

普段 I don't usually work very close to the OS, so I think the usage of the term may be inappropriate, but I appreciate your cooperation.

[Additional note: 2020-10-11]
When I ask this kind of question, after receiving comments and answers, I realize the inaccuracy of my questioning method. I was only thinking about .dll and .so specific static data. I'm very sorry to those who already answered, but I added parts that should have been written in italics and bold.

That's it