From ddac5f9e5aa935f4c154253831a36e49a48cdc8d Mon Sep 17 00:00:00 2001 From: hallgren Date: Tue, 19 Nov 2013 15:18:58 +0000 Subject: GF shell: improved system_pipe (aka "?") command 1. No temporary files are created. 2. The output of a system command is read lazily, making it feasible to process large or even infinite output, e.g. the following works as expected: ? "yes" | ? "head -5" | ps -lextext --- src/compiler/GF/System/Process.hs | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) create mode 100644 src/compiler/GF/System/Process.hs (limited to 'src/compiler/GF/System/Process.hs') diff --git a/src/compiler/GF/System/Process.hs b/src/compiler/GF/System/Process.hs new file mode 100644 index 000000000..415f8a50a --- /dev/null +++ b/src/compiler/GF/System/Process.hs @@ -0,0 +1,18 @@ +module GF.System.Process where +import System.Process +import System.IO(hGetContents,hClose,hPutStr) +import Control.Concurrent(forkIO) +import GF.System.Catch(try) + +-- | Feed some input to a shell process and read the output lazily +readShellProcess :: String -- ^ shell command + -> String -- ^ input to shell command + -> IO String -- ^ output from shell command +readShellProcess cmd input = + do (Just stdin,Just stdout,Nothing,ph) <- + createProcess (shell cmd){std_in=CreatePipe,std_out=CreatePipe} + forkIO $ do try $ hPutStr stdin input + try $ hClose stdin + waitForProcess ph + return () + hGetContents stdout -- cgit v1.2.3