touch: add support for touching files in directory, with options for recursive, filtering and dry-run/interactive

Fixes #5301

fs/operations/operations.go

@@ -1906,6 +1906,23 @@ func SetTier(ctx context.Context, fsrc fs.Fs, tier string) error {
 	})
 }
 
+// TouchDir touches every file in f with time t
+func TouchDir(ctx context.Context, f fs.Fs, t time.Time, recursive bool) error {
+	return walk.ListR(ctx, f, "", false, ConfigMaxDepth(ctx, recursive), walk.ListObjects, func(entries fs.DirEntries) error {
+		entries.ForObject(func(o fs.Object) {
+			if !SkipDestructive(ctx, o, "touch") {
+				fs.Debugf(f, "Touching %q", o.Remote())
+				err := o.SetModTime(ctx, t)
+				if err != nil {
+					err = fs.CountError(err)
+					fs.Errorf(o, "Failed to touch %v", err)
+				}
+			}
+		})
+		return nil
+	})
+}
+
 // ListFormat defines files information print format
 type ListFormat struct {
 	separator string