How does bat expand and canonicalize UNIX paths?

[kirusfg]

In a project of mine I have to deal with files provided by users, and those can be of the shortened form ~/path/to/some/file or be a /symlink/to/another/file.

While the canonicalize method from std::fs has been sufficient in resolving links, I am yet to find a proper way of expanding paths containing tildes (~). How does bat approach this?

[Enselic]

I don't think we have special code to expand ~? May I ask why you think we have? Most of the magic we have regarding handling of paths is likely implemented by Rust libstd.

[sharkdp]

I have experienced in the past that it is not well known that ~ is not some special path on Linux. Or something that every Linux application supports. ~ is a shell feature. If you run echo ~, you will see that your shell expands ~ to your home directory path. So if someone calls bat ~/file, bat will never see that ~ character. It does not need special handling for the ~ symbol.

The question is probably hinting at what happens if bat actually sees that ~ symbol (?). Like if you call bat '~/file'. The answer is that this will lead to a "No such file or directory" error. And that's the only reasonable thing to do (and the exact same thing that other Unix applications would also do). Because there could actually be a folder called ~, with a file called file inside. Again: there is nothing special about the ~ symbol when it comes to Linux paths.

I guess that some applications probably have a expanduser feature where they would also resolve a literal ~/file to /home/xxx/file. But I don't think that's good practice.

[Enselic]

Yeah, the way this played out in my head was that @kirusfg was going to say "but why does bat ~/file.rs work with bat then? And then I would explain what you explained above :) But I wouldn't have done such a stellar job of it as you did.

You probably want this as a top-level answer directed at @kirusfg though, right?

If not: @kirusfg see above

[kirusfg]

Thanks for your exhaustive answers!

I did not know that ~ is a shell-only feature, and the problem I have is not in expanding this character when getting the path from the shell, but rather when parsing a configuration file.

Crates like dirs and shellexpand seem to offer what I need.

Again, thanks for answering despite this having very little to do with bat itself.