Reading / Writing to several launched processes command lines

Question

I was wondering if it is possible to read the input stream / write to the output stream of several launched processes.

I'm asking this as from my current (weak) understanding of how reading / writing to launched processes work, it surely looks as it attaches the input / output streams to my program's console input / output stream.

Is this, indeed, the case? If that's the case, then reading/writing different data to several launched command lines would prove complicated, if not impossible, not achieve.

Is my understanding correct? How to deal with several launched command lines?

---

Some code:

open System
open System.IO
open System.Diagnostics
open System.Threading

[<EntryPoint>]
let main argv = 
    let startInfo = ProcessStartInfo()
    startInfo.FileName <- "cmd.exe"
    startInfo.UseShellExecute <- false
    startInfo.RedirectStandardInput <- true
    startInfo.RedirectStandardOutput <- true
    let proc = Process.Start(startInfo)
    proc.StandardInput.WriteLine("svn log")
    Console.ReadKey() |> ignore
    0

This code, as it is, will print

svn: E155007: 'C:\x\y\z\bin\Debug' is not a working copy

Answer 1

" it surely looks as it attaches the input / output streams to my program's console input / output stream."

Not true. You can tell the process to redirect stdin via myProcess.StartInfo.RedirectStandardInput . The Process object exposes methods to get to the input/output streams (eg Process.StandardInput ) to read/write them.

MSDN has some decent example code:

http://msdn.microsoft.com/en-us/library/system.diagnostics.process.standardinput%28v=vs.110%29.aspx