[lua] file

--file open
-- r : Read only
-- w : overwrite or create a new file
-- a : Append or create a new file
-- r+ : Read & Write existing file
-- w+ : Overwrite read or create a file
-- a+ : Append read or create file

file = assert(io.open("test.txt", "w"))
file:write("Hello World")
file:close()

 

-- http://lua-users.org/wiki/FileInputOutput

-- see if the file exists
function file_exists(file)
  local f = io.open(file, "rb")
  if f then f:close() end
  return f ~= nil
end

-- get all lines from a file, returns an empty 
-- list/table if the file does not exist
function lines_from(file)
  if not file_exists(file) then return {} end
  lines = {}
  for line in io.lines(file) do 
    lines[#lines + 1] = line
  end
  return lines
end

-- tests the functions above
local file = 'test.lua'
local lines = lines_from(file)

-- print all line numbers and their contents
for k,v in pairs(lines) do
  print('line[' .. k .. ']', v)
end

https://stackoverflow.com/questions/6889589/create-a-new-file-in-lua-luafilesystem