Connect to Unix domain socket as client in Haskel

Question

I can't find a good info on dealing with Unix Domain sockets in Haskell. I need a simple function to open a socket and write a command to it. Can anyone help me with an advice of where to read about this or maybe give an example?

Basically, I need to port this simple Ruby function (if it helps to understand what I mean):

def monitor(string_command)
  require "socket"
  socket = File.join($vbase, @name, "monitor.soc")
  raise RuntimeError, "Monitor socket does not exst!" unless File.exist? socket
  begin
    UNIXSocket.open(socket) do |s|
      s.puts string_command
      s.flush
    end
  rescue
    return false
  end
  true
end

All it does opens socket and writes a command to it returning true upon success. Thank you.

You should put your answer on as an answer and accept it, so that this question does not show up as unanswered. — singpolyma, Feb 19 '13 at 02:41

score 11 · Accepted Answer · answered Nov 15 '13 at 01:50

I think I figured it out. Well, it works and does what I need so I guess it should do for now.

Here is the snippet (without any error checks) if some one needs a similar thing:

monitor n c = do
  soc <- socket AF_UNIX Stream 0
  connect soc (SockAddrUnix (vmBaseDir </> n </> "monitor.soc"))
  send soc (c ++ "\n")
  sClose soc

score 1 · Answer 2 · answered May 27 '20 at 18:44

Here is a full example:

{-# Language OverloadedStrings #-}
module Main where

import Network.Socket hiding (send)
import Network.Socket.ByteString

main :: IO ()
main = do
  withSocketsDo $ do
    soc <- socket AF_UNIX Stream 0
    connect (soc) (SockAddrUnix "/tmp2/test2.soc")
    send soc ("test123")
    close soc

Connect to Unix domain socket as client in Haskel

2 Answers2