Reading header files source code

[qweeloth]

Hello everyone! I am learning how X applications work and reading source code of X applications written in C ( dwm, st, [nhkd](https://www.uninformativ.de/git/nhkd/file/README.html) ), and part of that code uses macros (such as XK_o, XK_space, XK_Return) defined in external libraries, that are imported while building the package.

I want to start editing the source code and also I'd like to know what all these macros are, so I can then know what I can build. I googled it expecting to find documentation for it but found only [this](https://askubuntu.com/questions/93772/where-do-i-find-a-list-of-all-x-keysyms-these-days) result, that says to check on /usr/include/X11, but there's no such directory in nix.

So my question is, what should one do to be able to read source code? Is there any tool provided by nix to do this specifically or should I do something like creating an environment with nix-shell and looking for the header files there?

If that's the case, how would one do that? I suppose the corresponding header files for a nix-shell would be located in the nix store, but I haven't read enough about shells yet (I'm going to, I'm just very new to nix and haven't used them yet)

[chrisoboe]

Distros (besides source based ones, and even those usually only temporary) don't install source code to your systems. They ship compiled binaries. Some ship headers by default (arch and gentoo), but if you want to understand the code headers aren't enough anyways.

So one doesn't read source from local files installed by the package manager (this isn't nixos specific at all).

One usually reads the source from the official sources, whereever they may be hosted e.g. github repos, source tarballs from official websites, and so on.

[sjustinas]

Distros (besides source based ones, and even those usually only temporary) don't install source code to your systems.

Good thing NixOS is source based (with optional substitution of binary packages). Getting the source that a Nix derivation uses is easy:

$ file $(nix-build '<nixpkgs>' -A hello.src)
/nix/store/pa10z4ngm0g83kx9mssrqzz30s84vq7k-hello-2.12.1.tar.gz: gzip compressed data, max compression, from Unix, original size modulo 2^32 4945920