fix typo, add lock file

Program.cs

@@ -13,8 +13,19 @@ namespace repomgr
     public static class Program
     {
         public static RepoMgr Repo;
+
         public static void Main(string[] args)
         {
+            if (File.Exists("/tmp/repomgr.lock"))
+            {
+                Console.WriteLine("/tmp/repomgr.lock exists, delete if you are sure that this is the only instance");
+                Environment.Exit(1);
+            }
+            else
+            {
+                File.Create("/tmp/repomgr.lock");
+            }
+
             if (args.Length < 2 || args[1].Equals("help"))
                 PrintHelp();
             Repo = new RepoMgr(args[0]);
@@ -36,6 +47,7 @@ namespace repomgr
                     {
                         Console.WriteLine("Init failed with error: " + e);
                     }
+
                     break;
                 case "add":
                     if (args.Length != 3)
@@ -48,6 +60,7 @@ namespace repomgr
                     {
                         Console.WriteLine("Add failed with error: " + e);
                     }
+
                     break;
                 case "update":
                     if (args.Length < 3 || args.Length > 4)
@@ -71,6 +84,7 @@ namespace repomgr
                     {
                         Console.WriteLine("Build failed with error: " + e);
                     }
+
                     break;
                 case "update-all":
                     if (args.Length != 2)
@@ -83,6 +97,7 @@ namespace repomgr
                     {
                         Console.WriteLine("BuildAll failed with error: " + e);
                     }
+
                     break;
                 case "remove":
                     if (args.Length != 3)
@@ -95,6 +110,7 @@ namespace repomgr
                     {
                         Console.WriteLine("Remove failed with error: " + e);
                     }
+
                     break;
                 case "list":
                     if (args.Length != 2)
@@ -107,11 +123,14 @@ namespace repomgr
                     {
                         Console.WriteLine("List failed with error " + e);
                     }
+
                     break;
                 default:
                     PrintHelp();
                     break;
             }
+
+            File.Delete("/tmp/repomgr.lock");
         }
 
         private static void PrintHelp()

RepoMgr.cs

@@ -205,7 +205,7 @@ namespace repomgr
             }
             catch (IOException)
             {
-                throw new Exception("Unable to write configuratoin. Check permissions.");
+                throw new Exception("Unable to write configuration. Check permissions.");
             }
         }
         private bool CheckPackage(string package)