Redirecting stdout of one process object to stdin of another

Question

How can I set up two external executables to run from a c# application where stdout from the first is routed to stdin from the second?

I know how to run external programs by using the Process object, but I don't see a way of doing something like "myprogram1 -some -options | myprogram2 -some -options". I'll also need to catch the stdout of the second program (myprogram2 in the example).

In PHP I would just do this:

$descriptorspec = array(
            1 => array("pipe", "w"),  // stdout
        );

$this->command_process_resource = proc_open("myprogram1 -some -options | myprogram2 -some -options", $descriptorspec, $pipes);

And $pipes[1] would be the stdout from the last program in the chain. Is there a way to accomplish this in c#?

Answer 1

You could use the System.Diagnostics.Process class to create the 2 external processes and stick the in and outs together via the StandardInput and StandardOutput properties.

Answer 2

Use System.Diagnostics.Process to start each process, and in the second process set the RedirectStandardOutput to true, and the in the first RedirectStandardInput true. Finally set the StandardInput of the first to the StandardOutput of the second . You'll need to use a ProcessStartInfo to start each process.

Here is an example of one of the redirections.

Answer 3

Here's a basic example of wiring the standard output of one process to the standard input of another.

Process out = new Process("program1.exe", "-some -options");
Process in = new Process("program2.exe", "-some -options");

out.UseShellExecute = false;

out.RedirectStandardOutput = true;
in.RedirectStandardInput = true;

using(StreamReader sr = new StreamReader(out.StandardOutput))
using(StreamWriter sw = new StreamWriter(in.StandardInput))
{
  string line;
  while((line = sr.ReadLine()) != null)
  {
    sw.WriteLine(line);
  }
}