Copyright exists at the moment you finish your product, without registration.
When developing software on Linux, as with any other OS, one must link one’s application with OS-provided libraries in order to `use the screen, write files, etc.
This linking can be to either “shared” libraries, so the application will not contain library executable code, just references to the libraries, or...
it can be done “statically”, where library executable code is copied from static copies of the libraries and included in the application executable.
One must take care to link “shared” when developing commercial software, because the “free software” folks will say you must include all your source code with your application (that you then will attempt to sell for money, but once the source is public, fat chance on that).
They say that when you statically link, your inclusion of system executable library code in your application makes it a derivative work, and thus subject to GPL’s open source requirement.
Now... if the moment I finish my last compile, and my application is done, I have a copyright in the product I created.
If I used Apple or M$ or one of many other OS’s, that would be clear.
But if I was using an open source OS, and I linked static - my copyright in my just finished work sits in conflict with the terms of my licensing of the open source OS.
Business law 101 tells us that:
If you and I sign a contract with each other, but that contract has provisions which conflict with then current statutes, the contract is null and void, unless it has an applicable severability clause, in which case only the conflicting clauses are null and void, and the rest of the contract would stand.
Not if the professor is even marginally competent it doesn't. The default rule is that a party to a commercial (as opposed to consumer) contract may waive their statutory rights unless the statute specifically forbids waiver.