Emit a warning when a destination file exists and won't be overwritten

README.md

@@ -60,4 +60,6 @@ You can also call ncp like `ncp(source, destination, options, callback)`.
 
   * `options.errs` - stream. If `options.stopOnErr` is `false`, a stream can be provided, and errors will be written to this stream.
 
+  * `options.warns` - stream of warnings (like a destination file already existing when clobber=false).
+
 Please open an issue if any bugs arise.  As always, I accept (working) pull requests, and refunds are available at `/dev/null`.

lib/ncp.js

@@ -94,6 +94,16 @@ function ncp (source, dest, options, callback) {
         rmFile(target, function () {
           copyFile(file, target);
         });
+      } else {
+        var warns = options.warns;
+        var warn = "destination file '" + target + "' already exists, skipping";
+        if (warns) {
+          if (typeof warns.write === 'undefined') {
+            warns.push(warn);
+          } else {
+            warns.write(warn);
+          }
+        }
       }
       if (modified) {
         var stat = dereference ? fs.stat : fs.lstat;