What is vim.loop.fs_stat()?

Question

My question is exactly as the heading. I can't find any good documentation explaining what it is and any usecase.

I found the code being used in many many lua.init files (the file where neovim configs are kept). I've included a snippet.

I know what it's doing. It is checking whether the path exists. But, why is it under loop and why is it called fs_stat? I'd greatly appreciate it if anyone could refer me to the documentation of vim or neovim that explains it.

Answer 1

First of all, vim.loop is now called vim.uv: https://github.com/neovim/neovim/pull/22846

But before that change, the documentation said this:

vim.loop exposes all features of the Nvim event-loop.

Anyway, that's the luv library for Lua (https://github.com/luvit/luv), which is a wrapper around the libuv library for C (https://github.com/libuv/libuv). luv calls it fs_stat because the library it's wrapping calls it uv_fs_stat. The fs part of the name is because it's a file system operation. The stat part of the name is because that's the name of the underlying syscall:

Equivalent to stat(2), fstat(2) and lstat(2) respectively.

And stat is short for status, and that syscall gets a file's status. (That might be one reason for your confusion: it can do a lot more than just check if a file exists.)