diff --git a/diversity.cabal b/diversity.cabal
--- a/diversity.cabal
+++ b/diversity.cabal
@@ -2,7 +2,7 @@
 -- documentation, see http://haskell.org/cabal/users-guide/
 
 name:                diversity
-version:             0.3.4.1
+version:             0.3.5.0
 synopsis:            Return the diversity at each position for all sequences in a fasta file
 description:         Find the diversity of a collection of entities, mainly for use with fasta sequences. Produces a binary which works on fasta files to find the diversity of any order and rarefaction curves for a sliding window across all positions in the sequences. To analyze just a collection of entities, just use the whole sequences and list flag.
 homepage:            https://github.com/GregorySchwartz/diversity
diff --git a/src/src-exec/Main.hs b/src/src-exec/Main.hs
--- a/src/src-exec/Main.hs
+++ b/src/src-exec/Main.hs
@@ -29,6 +29,7 @@
                        , list                   :: Bool
                        , sample                 :: Bool
                        , rarefactionDF          :: Bool
+                       , std                    :: Bool
                        , outputRarefaction      :: String
                        , outputRarefactionCurve :: String
                        , output                 :: String
@@ -106,6 +107,11 @@
           ( long "rarefaction-df"
          <> short 'd'
          <> help "Whether to output the rarefaction curve as a data frame" )
+      <*> switch
+          ( long "std"
+         <> short 't'
+         <> help "Whether to output to stdout or to a file if no file is\
+                 \ supplied" )
       <*> strOption
           ( long "output-rarefaction"
          <> short 'O'
@@ -129,7 +135,9 @@
 
 generateDiversity :: Options -> IO ()
 generateDiversity opts = do
-    contentsFile <- readFile . inputFasta $ opts
+    contentsFile    <- if (null . inputFasta $ opts)
+                        then getContents
+                        else readFile . inputFasta $ opts
     let lineIt       = unlines . (:) ">" . intersperse ">" . lines
         contents     = if (list opts) then lineIt contentsFile else contentsFile
         label        = inputLabel opts
@@ -149,14 +157,16 @@
                        window
                        fastaList
 
+        howToOutput x = if std opts then putStrLn else writeFile x
+
     if (null . output $ opts)
         then return ()
-        else writeFile (output opts)
+        else howToOutput (output opts)
            . printDiversity label order window
            $ positionMap
     if (null . outputRarefaction $ opts)
         then return ()
-        else writeFile (outputRarefaction opts)
+        else howToOutput (outputRarefaction opts)
            $ printRarefaction
              (sample opts)
              (fastBin opts)
@@ -167,16 +177,16 @@
              positionMap
     if (null . outputRarefactionCurve $ opts)
         then return ()
-        else writeFile (outputRarefactionCurve opts) $
-            printRarefactionCurve
-            (rarefactionDF opts)
-            (sample opts)
-            (fastBin opts)
-            start
-            interval
-            label
-            window
-            positionMap
+        else howToOutput (outputRarefactionCurve opts)
+           $ printRarefactionCurve
+             (rarefactionDF opts)
+             (sample opts)
+             (fastBin opts)
+             start
+             interval
+             label
+             window
+             positionMap
 
 main :: IO ()
 main = execParser opts >>= generateDiversity