Amazon EC2 인스턴스 시작

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using System;
using System.Threading;
using System.Threading.Tasks;
using System.Collections.Generic;
using Amazon.EC2;
using Amazon.EC2.Model;

namespace EC2LaunchInstance
{
  // = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
  // Class to launch an EC2 instance
  class Program
  {
    static async Task Main(string[] args)
    {
      // Parse the command line and show help if necessary
      var parsedArgs = CommandLine.Parse(args);
      if(parsedArgs.Count == 0)
      {
        PrintHelp();
        return;
      }

      // Get the application arguments from the parsed list
      string groupID =
        CommandLine.GetArgument(parsedArgs, null, "-g", "--group-id");
      string ami =
        CommandLine.GetArgument(parsedArgs, null, "-a", "--ami-id");
      string keyPairName =
        CommandLine.GetArgument(parsedArgs, null, "-k", "--keypair-name");
      string subnetID =
        CommandLine.GetArgument(parsedArgs, null, "-s", "--subnet-id");
      if(   (string.IsNullOrEmpty(groupID) || !groupID.StartsWith("sg-"))
         || (string.IsNullOrEmpty(ami) || !ami.StartsWith("ami-"))
         || (string.IsNullOrEmpty(keyPairName))
         || (!string.IsNullOrEmpty(subnetID) && !subnetID.StartsWith("subnet-")))
        CommandLine.ErrorExit(
          "\nOne or more of the required arguments is missing or incorrect." +
          "\nRun the command with no arguments to see help.");

      // Create an EC2 client
      var ec2Client = new AmazonEC2Client();

      // Create an object with the necessary properties
      RunInstancesRequest request = GetRequestData(groupID, ami, keyPairName, subnetID);

      // Launch the instances and wait for them to start running
      var instanceIds = await LaunchInstances(ec2Client, request);
      await CheckState(ec2Client, instanceIds);
    }


    //
    // Method to put together the properties needed to launch the instance.
    private static RunInstancesRequest GetRequestData(
      string groupID, string ami, string keyPairName, string subnetID)
    {
      // Common properties
      var groupIDs = new List<string>() { groupID };
      var request = new RunInstancesRequest()
      {
        // The first three of these would be additional command-line arguments or similar.
        InstanceType = InstanceType.T1Micro,
        MinCount = 1,
        MaxCount = 1,
        ImageId = ami,
        KeyName = keyPairName
      };

      // Properties specifically for EC2 in a VPC.
      if(!string.IsNullOrEmpty(subnetID))
      {
        request.NetworkInterfaces =
          new List<InstanceNetworkInterfaceSpecification>() {
            new InstanceNetworkInterfaceSpecification() {
              DeviceIndex = 0,
              SubnetId = subnetID,
              Groups = groupIDs,
              AssociatePublicIpAddress = true
            }
          };
      }

      // Properties specifically for EC2-Classic
      else
      {
        request.SecurityGroupIds = groupIDs;
      }
      return request;
    }


    //
    // Method to launch the instances
    // Returns a list with the launched instance IDs
    private static async Task<List<string>> LaunchInstances(
      IAmazonEC2 ec2Client, RunInstancesRequest requestLaunch)
    {
      var instanceIds = new List<string>();
      RunInstancesResponse responseLaunch =
        await ec2Client.RunInstancesAsync(requestLaunch);

      Console.WriteLine("\nNew instances have been created.");
      foreach (Instance item in responseLaunch.Reservation.Instances)
      {
        instanceIds.Add(item.InstanceId);
        Console.WriteLine($"  New instance: {item.InstanceId}");
      }

      return instanceIds;
    }


    //
    // Method to wait until the instances are running (or at least not pending)
    private static async Task CheckState(IAmazonEC2 ec2Client, List<string> instanceIds)
    {
      Console.WriteLine(
        "\nWaiting for the instances to start." +
        "\nPress any key to stop waiting. (Response might be slightly delayed.)");

      int numberRunning;
      DescribeInstancesResponse responseDescribe;
      var requestDescribe = new DescribeInstancesRequest{
        InstanceIds = instanceIds};

      // Check every couple of seconds
      int wait = 2000;
      while(true)
      {
        // Get and check the status for each of the instances to see if it's past pending.
        // Once all instances are past pending, break out.
        // (For this example, we are assuming that there is only one reservation.)
        Console.Write(".");
        numberRunning = 0;
        responseDescribe = await ec2Client.DescribeInstancesAsync(requestDescribe);
        foreach(Instance i in responseDescribe.Reservations[0].Instances)
        {
          // Check the lower byte of State.Code property
          // Code == 0 is the pending state
          if((i.State.Code & 255) > 0) numberRunning++;
        }
        if(numberRunning == responseDescribe.Reservations[0].Instances.Count)
          break;

        // Wait a bit and try again (unless the user wants to stop waiting)
        Thread.Sleep(wait);
        if(Console.KeyAvailable)
          break;
      }

      Console.WriteLine("\nNo more instances are pending.");
      foreach(Instance i in responseDescribe.Reservations[0].Instances)
      {
        Console.WriteLine($"For {i.InstanceId}:");
        Console.WriteLine($"  VPC ID: {i.VpcId}");
        Console.WriteLine($"  Instance state: {i.State.Name}");
        Console.WriteLine($"  Public IP address: {i.PublicIpAddress}");
        Console.WriteLine($"  Public DNS name: {i.PublicDnsName}");
        Console.WriteLine($"  Key pair name: {i.KeyName}");
      }
    }


    //
    // Command-line help
    private static void PrintHelp()
    {
      Console.WriteLine(
        "\nUsage: EC2LaunchInstance -g <group-id> -a <ami-id> -k <keypair-name> [-s <subnet-id>]" +
        "\n  -g, --group-id: The ID of the security group." +
        "\n  -a, --ami-id: The ID of an Amazon Machine Image." +
        "\n  -k, --keypair-name - The name of a key pair." +
        "\n  -s, --subnet-id: The ID of a subnet. Required only for EC2 in a VPC.");
    }
  }


  // = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
  // Class that represents a command line on the console or terminal.
  // (This is the same for all examples. When you have seen it once, you can ignore it.)
  static class CommandLine
  {
    //
    // Method to parse a command line of the form: "--key value" or "-k value".
    //
    // Parameters:
    // - args: The command-line arguments passed into the application by the system.
    //
    // Returns:
    // A Dictionary with string Keys and Values.
    //
    // If a key is found without a matching value, Dictionary.Value is set to the key
    //  (including the dashes).
    // If a value is found without a matching key, Dictionary.Key is set to "--NoKeyN",
    //  where "N" represents sequential numbers.
    public static Dictionary<string,string> Parse(string[] args)
    {
      var parsedArgs = new Dictionary<string,string>();
      int i = 0, n = 0;
      while(i < args.Length)
      {
        // If the first argument in this iteration starts with a dash it's an option.
        if(args[i].StartsWith("-"))
        {
          var key = args[i++];
          var value = key;

          // Check to see if there's a value that goes with this option?
          if((i < args.Length) && (!args[i].StartsWith("-"))) value = args[i++];
          parsedArgs.Add(key, value);
        }

        // If the first argument in this iteration doesn't start with a dash, it's a value
        else
        {
          parsedArgs.Add("--NoKey" + n.ToString(), args[i++]);
          n++;
        }
      }

      return parsedArgs;
    }

    //
    // Method to get an argument from the parsed command-line arguments
    //
    // Parameters:
    // - parsedArgs: The Dictionary object returned from the Parse() method (shown above).
    // - defaultValue: The default string to return if the specified key isn't in parsedArgs.
    // - keys: An array of keys to look for in parsedArgs.
    public static string GetArgument(
      Dictionary<string,string> parsedArgs, string defaultReturn, params string[] keys)
    {
      string retval = null;
      foreach(var key in keys)
        if(parsedArgs.TryGetValue(key, out retval)) break;
      return retval ?? defaultReturn;
    }

    //
    // Method to exit the application with an error.
    public static void ErrorExit(string msg, int code=1)
    {
      Console.WriteLine("\nError");
      Console.WriteLine(msg);
      Environment.Exit(code);
    }
  }

}

using System;
using System.Threading;
using System.Threading.Tasks;
using System.Collections.Generic;
using Amazon.EC2;
using Amazon.EC2.Model;

namespace EC2LaunchInstance
{
  // = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
  // Class to launch an EC2 instance
  class Program
  {
    static async Task Main(string[] args)
    {
      // Parse the command line and show help if necessary
      var parsedArgs = CommandLine.Parse(args);
      if(parsedArgs.Count == 0)
      {
        PrintHelp();
        return;
      }

      // Get the application arguments from the parsed list
      string groupID =
        CommandLine.GetArgument(parsedArgs, null, "-g", "--group-id");
      string ami =
        CommandLine.GetArgument(parsedArgs, null, "-a", "--ami-id");
      string keyPairName =
        CommandLine.GetArgument(parsedArgs, null, "-k", "--keypair-name");
      string subnetID =
        CommandLine.GetArgument(parsedArgs, null, "-s", "--subnet-id");
      if(   (string.IsNullOrEmpty(groupID) || !groupID.StartsWith("sg-"))
         || (string.IsNullOrEmpty(ami) || !ami.StartsWith("ami-"))
         || (string.IsNullOrEmpty(keyPairName))
         || (!string.IsNullOrEmpty(subnetID) && !subnetID.StartsWith("subnet-")))
        CommandLine.ErrorExit(
          "\nOne or more of the required arguments is missing or incorrect." +
          "\nRun the command with no arguments to see help.");

      // Create an EC2 client
      var ec2Client = new AmazonEC2Client();

      // Create an object with the necessary properties
      RunInstancesRequest request = GetRequestData(groupID, ami, keyPairName, subnetID);

      // Launch the instances and wait for them to start running
      var instanceIds = await LaunchInstances(ec2Client, request);
      await CheckState(ec2Client, instanceIds);
    }


    //
    // Method to put together the properties needed to launch the instance.
    private static RunInstancesRequest GetRequestData(
      string groupID, string ami, string keyPairName, string subnetID)
    {
      // Common properties
      var groupIDs = new List<string>() { groupID };
      var request = new RunInstancesRequest()
      {
        // The first three of these would be additional command-line arguments or similar.
        InstanceType = InstanceType.T1Micro,
        MinCount = 1,
        MaxCount = 1,
        ImageId = ami,
        KeyName = keyPairName
      };

      // Properties specifically for EC2 in a VPC.
      if(!string.IsNullOrEmpty(subnetID))
      {
        request.NetworkInterfaces =
          new List<InstanceNetworkInterfaceSpecification>() {
            new InstanceNetworkInterfaceSpecification() {
              DeviceIndex = 0,
              SubnetId = subnetID,
              Groups = groupIDs,
              AssociatePublicIpAddress = true
            }
          };
      }

      // Properties specifically for EC2-Classic
      else
      {
        request.SecurityGroupIds = groupIDs;
      }
      return request;
    }


    //
    // Method to launch the instances
    // Returns a list with the launched instance IDs
    private static async Task<List<string>> LaunchInstances(
      IAmazonEC2 ec2Client, RunInstancesRequest requestLaunch)
    {
      var instanceIds = new List<string>();
      RunInstancesResponse responseLaunch =
        await ec2Client.RunInstancesAsync(requestLaunch);

      Console.WriteLine("\nNew instances have been created.");
      foreach (Instance item in responseLaunch.Reservation.Instances)
      {
        instanceIds.Add(item.InstanceId);
        Console.WriteLine($"  New instance: {item.InstanceId}");
      }

      return instanceIds;
    }


    //
    // Method to wait until the instances are running (or at least not pending)
    private static async Task CheckState(IAmazonEC2 ec2Client, List<string> instanceIds)
    {
      Console.WriteLine(
        "\nWaiting for the instances to start." +
        "\nPress any key to stop waiting. (Response might be slightly delayed.)");

      int numberRunning;
      DescribeInstancesResponse responseDescribe;
      var requestDescribe = new DescribeInstancesRequest{
        InstanceIds = instanceIds};

      // Check every couple of seconds
      int wait = 2000;
      while(true)
      {
        // Get and check the status for each of the instances to see if it's past pending.
        // Once all instances are past pending, break out.
        // (For this example, we are assuming that there is only one reservation.)
        Console.Write(".");
        numberRunning = 0;
        responseDescribe = await ec2Client.DescribeInstancesAsync(requestDescribe);
        foreach(Instance i in responseDescribe.Reservations[0].Instances)
        {
          // Check the lower byte of State.Code property
          // Code == 0 is the pending state
          if((i.State.Code & 255) > 0) numberRunning++;
        }
        if(numberRunning == responseDescribe.Reservations[0].Instances.Count)
          break;

        // Wait a bit and try again (unless the user wants to stop waiting)
        Thread.Sleep(wait);
        if(Console.KeyAvailable)
          break;
      }

      Console.WriteLine("\nNo more instances are pending.");
      foreach(Instance i in responseDescribe.Reservations[0].Instances)
      {
        Console.WriteLine($"For {i.InstanceId}:");
        Console.WriteLine($"  VPC ID: {i.VpcId}");
        Console.WriteLine($"  Instance state: {i.State.Name}");
        Console.WriteLine($"  Public IP address: {i.PublicIpAddress}");
        Console.WriteLine($"  Public DNS name: {i.PublicDnsName}");
        Console.WriteLine($"  Key pair name: {i.KeyName}");
      }
    }


    //
    // Command-line help
    private static void PrintHelp()
    {
      Console.WriteLine(
        "\nUsage: EC2LaunchInstance -g <group-id> -a <ami-id> -k <keypair-name> [-s <subnet-id>]" +
        "\n  -g, --group-id: The ID of the security group." +
        "\n  -a, --ami-id: The ID of an Amazon Machine Image." +
        "\n  -k, --keypair-name - The name of a key pair." +
        "\n  -s, --subnet-id: The ID of a subnet. Required only for EC2 in a VPC.");
    }
  }


  // = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
  // Class that represents a command line on the console or terminal.
  // (This is the same for all examples. When you have seen it once, you can ignore it.)
  static class CommandLine
  {
    //
    // Method to parse a command line of the form: "--key value" or "-k value".
    //
    // Parameters:
    // - args: The command-line arguments passed into the application by the system.
    //
    // Returns:
    // A Dictionary with string Keys and Values.
    //
    // If a key is found without a matching value, Dictionary.Value is set to the key
    //  (including the dashes).
    // If a value is found without a matching key, Dictionary.Key is set to "--NoKeyN",
    //  where "N" represents sequential numbers.
    public static Dictionary<string,string> Parse(string[] args)
    {
      var parsedArgs = new Dictionary<string,string>();
      int i = 0, n = 0;
      while(i < args.Length)
      {
        // If the first argument in this iteration starts with a dash it's an option.
        if(args[i].StartsWith("-"))
        {
          var key = args[i++];
          var value = key;

          // Check to see if there's a value that goes with this option?
          if((i < args.Length) && (!args[i].StartsWith("-"))) value = args[i++];
          parsedArgs.Add(key, value);
        }

        // If the first argument in this iteration doesn't start with a dash, it's a value
        else
        {
          parsedArgs.Add("--NoKey" + n.ToString(), args[i++]);
          n++;
        }
      }

      return parsedArgs;
    }

    //
    // Method to get an argument from the parsed command-line arguments
    //
    // Parameters:
    // - parsedArgs: The Dictionary object returned from the Parse() method (shown above).
    // - defaultValue: The default string to return if the specified key isn't in parsedArgs.
    // - keys: An array of keys to look for in parsedArgs.
    public static string GetArgument(
      Dictionary<string,string> parsedArgs, string defaultReturn, params string[] keys)
    {
      string retval = null;
      foreach(var key in keys)
        if(parsedArgs.TryGetValue(key, out retval)) break;
      return retval ?? defaultReturn;
    }

    //
    // Method to exit the application with an error.
    public static void ErrorExit(string msg, int code=1)
    {
      Console.WriteLine("\nError");
      Console.WriteLine(msg);
      Environment.Exit(code);
    }
  }

}

NuGet 패키지:

프로그래밍 요소:

using System;
using System.Collections.Generic;
using System.IO;
using System.Threading.Tasks;
using Amazon.EC2;
using Amazon.EC2.Model;

namespace EC2GetWindowsPassword
{
  // = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
  // Class to get the Administrator password of a Windows EC2 instance
  class Program
  {
    static async Task Main(string[] args)
    {
      // Parse the command line and show help if necessary
      var parsedArgs = CommandLine.Parse(args);
      if(parsedArgs.Count == 0)
      {
        PrintHelp();
        return;
      }

      // Get the application arguments from the parsed list
      string instanceID =
        CommandLine.GetArgument(parsedArgs, null, "-i", "--instance-id");
      string pemFileName =
        CommandLine.GetArgument(parsedArgs, null, "-p", "--pem-filename");
      if(   (string.IsNullOrEmpty(instanceID) || !instanceID.StartsWith("i-"))
         || (string.IsNullOrEmpty(pemFileName) || !pemFileName.EndsWith(".pem")))
        CommandLine.ErrorExit(
          "\nOne or more of the required arguments is missing or incorrect." +
          "\nRun the command with no arguments to see help.");

      // Create the EC2 client
      var ec2Client = new AmazonEC2Client();

      // Get and display the password
      string password = await GetPassword(ec2Client, instanceID, pemFileName);
      Console.WriteLine($"\nPassword: {password}");
    }


    //
    // Method to get the administrator password of a Windows EC2 instance
    private static async Task<string> GetPassword(
      IAmazonEC2 ec2Client, string instanceID, string pemFilename)
    {
      string password = string.Empty;
      GetPasswordDataResponse response =
        await ec2Client.GetPasswordDataAsync(new GetPasswordDataRequest{
          InstanceId = instanceID});
      if(response.PasswordData != null)
      {
        password = response.GetDecryptedPassword(File.ReadAllText(pemFilename));
      }
      else
      {
        Console.WriteLine($"\nThe password is not available for instance {instanceID}.");
        Console.WriteLine($"If this is a Windows instance, the password might not be ready.");
      }
      return password;
    }


    //
    // Command-line help
    private static void PrintHelp()
    {
      Console.WriteLine(
        "\nUsage: EC2GetWindowsPassword -i <instance-id> -p pem-filename" +
        "\n  -i, --instance-id: The name of the EC2 instance." +
        "\n  -p, --pem-filename: The name of the PEM file with the private key.");
    }
  }

  // = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
  // Class that represents a command line on the console or terminal.
  // (This is the same for all examples. When you have seen it once, you can ignore it.)
  static class CommandLine
  {
    //
    // Method to parse a command line of the form: "--key value" or "-k value".
    //
    // Parameters:
    // - args: The command-line arguments passed into the application by the system.
    //
    // Returns:
    // A Dictionary with string Keys and Values.
    //
    // If a key is found without a matching value, Dictionary.Value is set to the key
    //  (including the dashes).
    // If a value is found without a matching key, Dictionary.Key is set to "--NoKeyN",
    //  where "N" represents sequential numbers.
    public static Dictionary<string,string> Parse(string[] args)
    {
      var parsedArgs = new Dictionary<string,string>();
      int i = 0, n = 0;
      while(i < args.Length)
      {
        // If the first argument in this iteration starts with a dash it's an option.
        if(args[i].StartsWith("-"))
        {
          var key = args[i++];
          var value = key;

          // Check to see if there's a value that goes with this option?
          if((i < args.Length) && (!args[i].StartsWith("-"))) value = args[i++];
          parsedArgs.Add(key, value);
        }

        // If the first argument in this iteration doesn't start with a dash, it's a value
        else
        {
          parsedArgs.Add("--NoKey" + n.ToString(), args[i++]);
          n++;
        }
      }

      return parsedArgs;
    }

    //
    // Method to get an argument from the parsed command-line arguments
    //
    // Parameters:
    // - parsedArgs: The Dictionary object returned from the Parse() method (shown above).
    // - defaultValue: The default string to return if the specified key isn't in parsedArgs.
    // - keys: An array of keys to look for in parsedArgs.
    public static string GetArgument(
      Dictionary<string,string> parsedArgs, string defaultReturn, params string[] keys)
    {
      string retval = null;
      foreach(var key in keys)
        if(parsedArgs.TryGetValue(key, out retval)) break;
      return retval ?? defaultReturn;
    }

    //
    // Method to exit the application with an error.
    public static void ErrorExit(string msg, int code=1)
    {
      Console.WriteLine("\nError");
      Console.WriteLine(msg);
      Environment.Exit(code);
    }
  }

}

using System;
using System.Collections.Generic;
using System.IO;
using System.Threading.Tasks;
using Amazon.EC2;
using Amazon.EC2.Model;

namespace EC2GetWindowsPassword
{
  // = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
  // Class to get the Administrator password of a Windows EC2 instance
  class Program
  {
    static async Task Main(string[] args)
    {
      // Parse the command line and show help if necessary
      var parsedArgs = CommandLine.Parse(args);
      if(parsedArgs.Count == 0)
      {
        PrintHelp();
        return;
      }

      // Get the application arguments from the parsed list
      string instanceID =
        CommandLine.GetArgument(parsedArgs, null, "-i", "--instance-id");
      string pemFileName =
        CommandLine.GetArgument(parsedArgs, null, "-p", "--pem-filename");
      if(   (string.IsNullOrEmpty(instanceID) || !instanceID.StartsWith("i-"))
         || (string.IsNullOrEmpty(pemFileName) || !pemFileName.EndsWith(".pem")))
        CommandLine.ErrorExit(
          "\nOne or more of the required arguments is missing or incorrect." +
          "\nRun the command with no arguments to see help.");

      // Create the EC2 client
      var ec2Client = new AmazonEC2Client();

      // Get and display the password
      string password = await GetPassword(ec2Client, instanceID, pemFileName);
      Console.WriteLine($"\nPassword: {password}");
    }


    //
    // Method to get the administrator password of a Windows EC2 instance
    private static async Task<string> GetPassword(
      IAmazonEC2 ec2Client, string instanceID, string pemFilename)
    {
      string password = string.Empty;
      GetPasswordDataResponse response =
        await ec2Client.GetPasswordDataAsync(new GetPasswordDataRequest{
          InstanceId = instanceID});
      if(response.PasswordData != null)
      {
        password = response.GetDecryptedPassword(File.ReadAllText(pemFilename));
      }
      else
      {
        Console.WriteLine($"\nThe password is not available for instance {instanceID}.");
        Console.WriteLine($"If this is a Windows instance, the password might not be ready.");
      }
      return password;
    }


    //
    // Command-line help
    private static void PrintHelp()
    {
      Console.WriteLine(
        "\nUsage: EC2GetWindowsPassword -i <instance-id> -p pem-filename" +
        "\n  -i, --instance-id: The name of the EC2 instance." +
        "\n  -p, --pem-filename: The name of the PEM file with the private key.");
    }
  }

  // = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
  // Class that represents a command line on the console or terminal.
  // (This is the same for all examples. When you have seen it once, you can ignore it.)
  static class CommandLine
  {
    //
    // Method to parse a command line of the form: "--key value" or "-k value".
    //
    // Parameters:
    // - args: The command-line arguments passed into the application by the system.
    //
    // Returns:
    // A Dictionary with string Keys and Values.
    //
    // If a key is found without a matching value, Dictionary.Value is set to the key
    //  (including the dashes).
    // If a value is found without a matching key, Dictionary.Key is set to "--NoKeyN",
    //  where "N" represents sequential numbers.
    public static Dictionary<string,string> Parse(string[] args)
    {
      var parsedArgs = new Dictionary<string,string>();
      int i = 0, n = 0;
      while(i < args.Length)
      {
        // If the first argument in this iteration starts with a dash it's an option.
        if(args[i].StartsWith("-"))
        {
          var key = args[i++];
          var value = key;

          // Check to see if there's a value that goes with this option?
          if((i < args.Length) && (!args[i].StartsWith("-"))) value = args[i++];
          parsedArgs.Add(key, value);
        }

        // If the first argument in this iteration doesn't start with a dash, it's a value
        else
        {
          parsedArgs.Add("--NoKey" + n.ToString(), args[i++]);
          n++;
        }
      }

      return parsedArgs;
    }

    //
    // Method to get an argument from the parsed command-line arguments
    //
    // Parameters:
    // - parsedArgs: The Dictionary object returned from the Parse() method (shown above).
    // - defaultValue: The default string to return if the specified key isn't in parsedArgs.
    // - keys: An array of keys to look for in parsedArgs.
    public static string GetArgument(
      Dictionary<string,string> parsedArgs, string defaultReturn, params string[] keys)
    {
      string retval = null;
      foreach(var key in keys)
        if(parsedArgs.TryGetValue(key, out retval)) break;
      return retval ?? defaultReturn;
    }

    //
    // Method to exit the application with an error.
    public static void ErrorExit(string msg, int code=1)
    {
      Console.WriteLine("\nError");
      Console.WriteLine(msg);
      Environment.Exit(code);
    }
  }

}