Question

If I have this code

local f = io.open("../web/", "r")
print(io.type(f))

-- output: file

how can I know if f points to a directory?

Answer 1

Lua’s default libraries don’t have a way to determine this.

However, you could use the third-party LuaFileSystem library to gain access to more advanced file-system interactions; it’s cross-platform as well.

LuaFileSystem provides lfs.attributes which you can use to query the file mode:

require "lfs"
function is_dir(path)
    -- lfs.attributes will error on a filename ending in '/'
    return path:sub(-1) == "/" or lfs.attributes(path, "mode") == "directory"
end