Vim recognizes and cares about file types. If I edit a file with "#!/bin/sh" at the top, I'd like vim to provide syntax highlighting for a shell script.

Well I wouldn't, and the entire purpose of using UNIX or a UNIX-like operating system is that such things are a strictly intimate, individual, private affair.

The example you cite serves extremely well for the purpose of illustration, of how there are no file types in UNIX, and how neither the operating system, nor the user should care.

Why should the user care? For example, I don't want files in the bin/ directory to have .pl, .py, .sh, .exe, or .com extension! Does it have an x bit set, thereby being executable? It does? OK, run it, and I couldn't and shouldn't care less what it's written in, because that's the main reason why I use UNIX to begin with!

Same for coloring: I hate colors in vim(1); hate, hate, hate, and do not need or want coloring in order to spot syntax errors, as I have the compiler, the linker, and the shell's set -x for that ("do one thing, and do it well")! Why should I suffer if you like colors and syntax highlighting? That should, and on UNIX is, an entirely private affair. GNU/Linux broke that, because users came from Windows, expecting GNU/Linux to behave like Windows but with a shell which isn't braindead. If I wanted to use Windows, I would be using it. If I wanted to use an integrated development environment again, I would be using it instead of vi(1) to write code. vi and vim, by the way, are text editors, dedicated to doing one thing and doing it well, and to expect them to behave like an integrated development environment leads to sadness, pain, misery and confusion.

UNIX does not have, recognize, or care about file types; consequently, it is up to the application to implement mechanism for dealing with the stream of bytes which the operating system does provide. In your case, that application is vim(1), and the file type recognition is proprietary to it. It has nothing whatsoever to do with the operating system.

On AmigaOS, where vim(1) comes from, no such vimrc file is provided; consequently, vim(1) doesn't treat .h, .c, or AmigaDOS shell scripts in any special way. This is because AmigaOS does implement data types, which are generic file type drivers, and still neither the operating system, nor the user care about file type extensions!

On Solaris and illumos-based operating systems, for example, vim packages do not deliver such customizations as they do on GNU/Linux, and consequently, there is no highlighting or any other special handling of .h, .c, or any other file type. (z/OS on the mainframe is even better, there are no files or byte streams to speak of, only records, and they are all binary.)

It's just a very bad Microsoft screw-up from MS-DOS days which has conditioned an entire generation of hapless Windows-now-turned-GNU/Linux users to still think of files in terms of file types and integrated development environments, because MS-DOS and Windows came without dedicated tools out of the box, so people started writing one-program-does-it-all, monolithic applications. What would you do on z/OS, where there are no files, just records?

This is one of the core concepts of UNIX: policy over mechanism; UNIX specifies policy (stream of bytes); mechanism is left up to the implementer.

Rule of Separation: Separate policy from mechanism; separate interfaces from engines.

http://www.catb.org/esr/writings/taoup/html/ch01s06.html#id2...

As someone who authored XCB, you should be no stranger to separation of policy from mechanism.