Concatenate output of multiple processes to StreamReader

I need to capture the ouput of three processes and pass it as a StreamReader. Is this possible in C#?

Background: I need the output of another file with three different arguments, but I want to treat the "complete" output (all three together) for latter processing in my code.

Should I just call the process three times and process the output in a loop? Or is there a more efficient way?

Currently, I'm doing it like this

if (String.IsNullOrEmpty(file))
{
    Process dsget;
    dsget = Process.Start("dsget", "group \"CN=COUNTRY_DE,DC=cms,DC=local\" -members");
    dsget.StartInfo.UseShellExecute = false;
    dsget.StartInfo.RedirectStandardOutput = true;
    dsge开发者_Go百科t.Start();
    reader = dsget.StandardOutput;
}
else 
{
    reader = new StreamReader(file);
}
while ((line = reader.ReadLine()) != null)
{
    if (!line.Contains("CN"))
        continue;
    string username = line.Replace("\"", "").Split(',')[0].Split('=')[1];
    countryUsers.Add(username.ToUpperInvariant());
}

But I need two more COUNTRY_XX-groups from "dsget".

There is no other way but to call the process three times. But you can always put process invocation code into a method that accepts argument as input add return the process output so you don't have to repeat the code. For example,

var info = new StringBuilder();
info.Append(InvokeProcess(argument1));
info.Append(InvokeProcess(argument2));
info.Append(InvokeProcess(argument3));

where InvokeProcess is more or less the code that you have already given.