How to call exe with parameters in c#?

In general, for every call to outside program, you use Process and ProcessStartInfo classes. If there is a default program set for particular file type you could even call the process directly, only with file name. Process.Start("test.txt") would open Notepad++ on my computer for example.

For your particular problem:

using System;
using System.Diagnostics;

public class Processing
{
    public static void Main()
    {
        Process p = new Process();
        p.StartInfo.FileName = "log.exe";
        p.StartInfo.Arguments = "port13.dat StringTable > porttest.txt";
        p.StartInfo.UseShellExecute = false;
        p.StartInfo.RedirectStandardOutput = true;
        p.Start();

        string output = p.StandardOutput.ReadToEnd();
        p.WaitForExit(); // This waits until the program called is closed

        Console.WriteLine("Output:");
        Console.WriteLine(output);    
    }
}

If this helps, please take time to accept the solution so that others may find it. Thank you.