005/104: logname

src/logname.hs

@@ -0,0 +1,14 @@
+{-# LANGUAGE NoImplicitPrelude #-}
+
+-- https://hackage.haskell.org/package/unix-2.7.2.2/docs/src/System.Posix.User.html#getLoginName
+
+import Prelude            (IO, putStrLn)
+import Control.Monad      ((>>=))
+import Foreign.C          (CString, peekCAString, throwErrnoIfNull)
+
+foreign import ccall unsafe "getlogin"
+    c_getlogin :: IO CString
+
+main :: IO ()
+main = throwErrnoIfNull "getLoginName" c_getlogin >>= peekCAString >>= putStrLn
+