How to catch and error message and how to make it create unix files instead of dos files??

[Alexandre Weffort Thenorio]

I am trying to write a small software to take info from one file and write it into another file. The problem is that when I don't give any input I get the normal haskell nosuchfile error message but I want to give my own error message. I am a newbie, how can I do that? Also I need the file that is gonna be created (A text file), to be created in UNIX type and not as a DOS file type, how can I do that? I am using ghc to compile on Windows.   Here is the main code   main :: IO() main = do  args <- getArgs  codes <- codes args  conax <- readconax "conax.txt"  makeIrdFile (lines codes) (lines conax)      --Read input file------------------------------------ codes :: [String] -> IO[Char] codes [] = return "" codes (x:xs) = do  first <- readFile x  return first   --Read Inbuilt file--------------------------------- readconax file = do  list <- readFile file  return list