You can also use my process-streaming library:

import System.Process.Streaming

import qualified Pipes.ByteString as B

-- collects stdout as a lazy ByteString

execute (pipeo (fromFold B.toLazyM)) (shell "echo test")

It depends on the pipes ecosystem and some other stuff, however.

Here are some examples.

On Thursday, December 11, 2014 10:11:09 AM UTC+1, Ernesto Rodriguez wrote:

Dear All,

I have a program which invokes an external program via exec. I wish to capture the standard output of the program without using external (temporary) files.