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diff --git a/CmdLine/Batch.hs b/CmdLine/Batch.hs
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+{- git-annex batch commands
+ -
+ - Copyright 2015 Joey Hess <id@joeyh.name>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module CmdLine.Batch where
+
+import Common.Annex
+import Command
+
+batchOption :: Option
+batchOption = flagOption [] "batch" "enable batch mode"
+
+data BatchMode = Batch | NoBatch
+type Batchable t = BatchMode -> t -> CommandStart
+
+-- A Batchable command can run in batch mode, or not.
+-- In batch mode, one line at a time is read, parsed, and a reply output to
+-- stdout. In non batch mode, the command's parameters are parsed and
+-- a reply output for each.
+batchable :: ((t -> CommandStart) -> CommandSeek) -> Batchable t -> CommandSeek
+batchable seeker starter params = ifM (getOptionFlag batchOption)
+	( batchloop
+	, seeker (starter NoBatch) params
+	)
+  where
+	batchloop = do
+		mp <- liftIO $ catchMaybeIO getLine
+		case mp of
+			Nothing -> return ()
+			Just p -> do
+				seeker (starter Batch) [p]
+				batchloop
+
+-- bad input is indicated by an empty line in batch mode. In non batch
+-- mode, exit on bad input.
+batchBadInput :: BatchMode -> Annex ()
+batchBadInput NoBatch = liftIO exitFailure
+batchBadInput Batch = liftIO $ putStrLn ""