The / K argument will execute the following command. It may be a whole team related to and, but this is what you were missing in your attempts, they should be completely enclosed in double quotes in this case. See link SS64 cmd
In other words, the command should look like this:
cmd /K " here what ever you want to execute"
- . , String.Format, , . , , :
ProcessStartInfo startInfo = new ProcessStartInfo();
startInfo.FileName = "cmd";
startInfo.Arguments = String.Format(
"/K \"{0}\"",
" \"D:\\as df\\solver\\Swag.Console.exe\" -f \"D:\\as df\\solver\\2035.swag\" -p 5555");
Process.Start(startInfo);
Swag.Console.Exe , :
-f
D:\as df\solver\2035.swag
-p
5555