diff --git a/Annex/Sim.hs b/Annex/Sim.hs
index d052bad763..42c3b8d437 100644
--- a/Annex/Sim.hs
+++ b/Annex/Sim.hs
@@ -531,7 +531,7 @@ applySimCommand' (CommandNotPresent _ _) _ _ = error "applySimCommand' CommandNo
 
 handleStep :: Bool -> Int -> Int -> SimState SimRepo -> Annex (SimState SimRepo)
 handleStep muststabilize startn n st
-	| n > 0 = do
+	| n >= 0 = do
 		let (st', actions) = getactions unsyncactions st
 		(st'', restactions) <- runoneaction actions st'
 		if null restactions
@@ -550,7 +550,7 @@ handleStep muststabilize startn n st
 	| otherwise = checkstabalized st
   where
 	runrest actions st' n'
-		| n' > 0 = do
+		| n' >= 0 = do
 			(st'', restactions) <- runoneaction actions st'
 			if null restactions
 				then handleStep muststabilize startn n' st'
diff --git a/Command/Sim.hs b/Command/Sim.hs
index 5682577321..f14142b069 100644
--- a/Command/Sim.hs
+++ b/Command/Sim.hs
@@ -22,19 +22,21 @@ cmd = command "sim" SectionTesting
 	paramCommand (withParams seek)
 
 seek :: CmdParams -> CommandSeek
-seek ("start":[]) = start Nothing
-seek ("start":simfile:[]) = start (Just simfile)
-seek ("end":[]) = do
-	simdir <- fromRawFilePath <$> fromRepo gitAnnexSimDir
-	whenM (liftIO $ doesDirectoryExist simdir) $ do
-		liftIO $ removeDirectoryRecursive simdir
-	showLongNote $ UnquotedString "Sim ended."
+seek ("start":[]) = startsim Nothing
+seek ("start":simfile:[]) = startsim (Just simfile)
+seek ("end":[]) = endsim
 seek ("show":[]) = do
 	simdir <- fromRepo gitAnnexSimDir
 	liftIO (restoreSim simdir) >>= \case
 		Left err -> giveup err
-		Right st -> liftIO $ putStr $ generateSimFile $
-			reverse $ simHistory st
+		Right st -> showsim st
+seek ("run":simfile:[]) = startsim' (Just simfile) >>= cleanup
+  where
+	cleanup st = do 
+		endsim
+		when (simFailed st) $ do
+			showsim st
+			giveup "Simulation shown above had errors."
 seek ps = case parseSimCommand ps of
 	Left err -> giveup err
 	Right simcmd -> do
@@ -48,8 +50,16 @@ seek ps = case parseSimCommand ps of
 				when (simFailed st' && not (simFailed st)) $
 					giveup "Simulation had errors."
 
-start :: Maybe FilePath -> CommandSeek
-start simfile = do
+startsim :: Maybe FilePath -> CommandSeek
+startsim simfile = startsim' simfile >>= cleanup
+  where
+	cleanup st = do
+		liftIO $ suspendSim st
+		when (simFailed st) $
+			giveup "Simulation had errors."
+
+startsim' :: Maybe FilePath -> Annex (SimState SimRepo)
+startsim' simfile = do
 	simdir <- fromRawFilePath <$> fromRepo gitAnnexSimDir
 	whenM (liftIO $ doesDirectoryExist simdir) $
 		giveup "A sim was previously started. Use `git-annex sim end` to stop it before starting a new one."
@@ -68,12 +78,19 @@ start simfile = do
 		repobyname <- mkGetExistingRepoByName
 		createAnnexDirectory (toRawFilePath simdir)
 		let st' = recordSeed st cs
-		st'' <- go st' repobyname cs
-		liftIO $ suspendSim st''
-		when (simFailed st'') $
-			giveup "Simulation had errors."
+		go st' repobyname cs
 
 	go st _ [] = return st
 	go st repobyname (c:cs) = do
 		st' <- runSimCommand c repobyname st
 		go st' repobyname cs
+	
+endsim :: CommandSeek
+endsim = do
+	simdir <- fromRawFilePath <$> fromRepo gitAnnexSimDir
+	whenM (liftIO $ doesDirectoryExist simdir) $ do
+		liftIO $ removeDirectoryRecursive simdir
+	showLongNote $ UnquotedString "Sim ended."
+		
+showsim :: SimState SimRepo -> Annex ()
+showsim = liftIO . putStr . generateSimFile . reverse . simHistory
diff --git a/doc/git-annex-sim.mdwn b/doc/git-annex-sim.mdwn
index 665e91fa63..09505ee9d4 100644
--- a/doc/git-annex-sim.mdwn
+++ b/doc/git-annex-sim.mdwn
@@ -12,6 +12,8 @@ git annex sim show
 
 git annex sim end
 
+git annex sim run my.sim
+
 # DESCRIPTION
 
 This command simulates the behavior of git-annex in a network of
@@ -32,6 +34,10 @@ as well as analyzing the results of the simulation.
 
 Use "git annex sim end" to finish the simulation, and clean up.
 
+As a convenience, to run a sim from a file, and then stop it, use
+"git-annex sim run". If there is a problem running the sim, it will be
+shown before it is stopped.
+
 # THE SIM FILE
 
 This text file is used to configure the simulation and also to report on
diff --git a/doc/sims/randomwanted.mdwn b/doc/sims/randomwanted.mdwn
new file mode 100644
index 0000000000..4896122346
--- /dev/null
+++ b/doc/sims/randomwanted.mdwn
@@ -0,0 +1,13 @@
+# This is a simulation of random preferred content expressions.  
+# git-annex sim run this in a loop to explore if an expression can fail to
+# stabilize
+init foo  
+init bar  
+connect foo <-> bar  
+addmulti 10 .x 100.0kB 10.0MB foo  
+addmulti 10 .y 100.0kB 10.0MB foo  
+randomwanted bar largerthan=1MB include=*.x anything present  
+randomwanted foo largerthan=1MB include=*.x anything present  
+# 40 is the maximum possible steps, in case bar wants to get all 20 files,  
+# and foo wants to drop them all  
+stepstable 40