dead --key: Can be used to mark a key as dead.

Command/Dead.hs

@@ -1,6 +1,6 @@
 {- git-annex command
  -
- - Copyright 2011 Joey Hess <id@joeyh.name>
+ - Copyright 2011, 2015 Joey Hess <id@joeyh.name>
  -
  - Licensed under the GNU GPL version 3 or higher.
  -}
@@ -8,12 +8,37 @@
 module Command.Dead where
 
 import Command
+import Common.Annex
+import qualified Annex
 import Types.TrustLevel
+import Types.Key
 import Command.Trust (trustCommand)
+import Logs.Location
+import Remote (keyLocations)
 
 cmd :: [Command]
-cmd = [command "dead" (paramRepeating paramRemote) seek
-	SectionSetup "hide a lost repository"]
+cmd = [withOptions [keyOption] $ 
+	command "dead" (paramRepeating paramRemote) seek
+		SectionSetup "hide a lost repository or key"]
 
 seek :: CommandSeek
-seek = trustCommand "dead" DeadTrusted
+seek ps = maybe (trustCommand "dead" DeadTrusted ps) (flip seekKey ps)
+	=<< Annex.getField "key"
+
+seekKey :: String -> CommandSeek
+seekKey ks = case file2key ks of
+	Nothing -> error "Invalid key"
+	Just key -> withNothing (startKey key)
+
+startKey :: Key -> CommandStart
+startKey key = do
+	showStart "dead" (key2file key)
+	ls <- keyLocations key
+	case ls of
+		[] -> next $ performKey key
+		_ -> error "This key is still known to be present in some locations; not marking as dead."
+		
+performKey :: Key -> CommandPerform
+performKey key = do
+	setDead key
+	next $ return True