c# - Redirect stdout, but stdout still appears -

i'm spawning child processes process.start. both process , child process console apps. stdout child process shows in parent console window. avoid this, redirected stdout, output still appearing. setup looks this:

        var proc = process.start(new processstartinfo         {             redirectstandardinput = true,             redirectstandardoutput = true,             redirectstandarderror = true,             useshellexecute = false,             filename = filename,             arguments = args,             createnowindow = false         });         var stderr = proc.standarderror.readtoendasync();         var stdout = proc.standardoutput.readtoendasync();         var stdin = proc.standardinput.writeasync(stdintext).continuewith(something => proc.standardinput.close());         proc.waitforexit();         task.waitall(stderr, stdout, stdin);         // process output 

i don't write stdout own stdout, it's still appearing in parent console. seems occur child processes , not others. don't have source tool being run here. how can stop output occurring?