[nvim] Add some Lua utils

nvim/lua/kdotfiles/utils.lua

@@ -0,0 +1,28 @@
+local M = require('dotfiles.autoload')('kdotfiles.utils')
+
+function M.file_exists(file)
+  local f = io.open(file, "rb")
+  if f then f:close() end
+  return f ~= nil
+end
+
+function M.lines_from(file)
+  if not M.file_exists(file) then return {} end
+  lines = {}
+  for line in io.lines(file) do
+    lines[#lines + 1] = line
+  end
+  return lines
+end
+
+function M.get_os(lines)
+  os_name = "Unknown"
+  for k,v in pairs(lines) do
+    if string.match(v, "^ID=") then
+      os_name = string.sub(v, 4)
+    end
+  end
+  return os_name
+end
+
+return M