Data commit

Task/Determine-if-only-one-instance-is-running/Delphi/determine-if-only-one-instance-is-running.delphi

@@ -0,0 +1,27 @@
+program OneInstance;
+
+{$APPTYPE CONSOLE}
+
+uses SysUtils, Windows;
+
+var
+  FMutex: THandle;
+begin
+  FMutex := CreateMutex(nil, True, 'OneInstanceMutex');
+  if FMutex = 0 then
+    RaiseLastOSError
+  else
+  begin
+    try
+      if GetLastError = ERROR_ALREADY_EXISTS then
+        Writeln('Program already running.  Closing...')
+      else
+      begin
+        // do stuff ...
+        Readln;
+      end;
+    finally
+      CloseHandle(FMutex);
+    end;
+  end;
+end.