Johannes Waldmann writes:
I have two (or more) threads (created by forkIO) and each does an external ( System.Cmd.system ) call. When the first of these returns, the others should be killed.
Unfortunately, 'timeout' doesn't help solving that problem. What you are looking for is 'terminateProcess': import System.IO import System.Process import Control.Concurrent ( threadDelay ) run :: FilePath -> Maybe Handle -> Maybe Handle -> IO ProcessHandle run cmd hin hout = runProcess cmd [] Nothing Nothing hin hout Nothing main :: IO () main = do pid <- withFile "/dev/urandom" ReadMode $ \hin -> withFile "/dev/null" WriteMode $ \hout -> run "/usr/bin/cat" (Just hin) (Just hout) threadDelay (5*10^6) -- sleep 5 seconds terminateProcess pid -- send kill signal waitForProcess pid >>= print -- wait on termination A mechanism that terminates all external processes once one of them terminates is easily defined using 'Control.Exception.bracket'. You'll find that the code structure is quite similar to timeout: main' :: IO () main' = do let start = withFile "/dev/urandom" ReadMode $ \hin -> withFile "/dev/null" WriteMode $ \hout -> run "/usr/bin/cat" (Just hin) (Just hout) stop p = terminateProcess p >> waitForProcess p bracket start stop $ \_ -> bracket start stop $ \_ -> bracket start stop $ \_ -> bracket start stop $ \_ -> return () -- kill em all NOW I hope this helps. Peter