c# - How to write to the stdin of another app?

Question

I have a module that reads the StandardError of a process. Everything works fine, but I want to do something different. I don't know how to redirect stdin like the native way:

app1.exe -someargs | app2.exe -someargs

Where app2 reads all the stdout of app1 in its stdin.

Answer 1

Once you have the Process object representing the process you want to communicate with (either because you got it from the OS using the static method Process.GetProcesses, or because you created it yourself), you can attach a StreamWriter to the Process.StandardInput property and use that to write to the stdin of the process. Don't forget to set ProcessStartInfo.RedirectStandardInput on your newly created process to true.

On a related note, you can use a StreamReader on the Process.StandardOutput to read the output (like reading from StandardError).