diff --git a/book_with_bridge/du/go.mod b/book_with_bridge/du/go.mod
new file mode 100644
index 0000000..371eb8f
--- /dev/null
+++ b/book_with_bridge/du/go.mod
@@ -0,0 +1,3 @@
+module main
+
+go 1.25.5
diff --git a/book_with_bridge/du/main.go b/book_with_bridge/du/main.go
new file mode 100644
index 0000000..db613d2
--- /dev/null
+++ b/book_with_bridge/du/main.go
@@ -0,0 +1,58 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+	"path/filepath"
+)
+
+func main() {
+	flag.Parse()
+	roots := flag.Args()
+	if len(roots) == 0 {
+		roots = []string{"."}
+	}
+
+	fileSizes := make(chan int64)
+
+	go func() {
+		for _,root := range roots {
+			WalkDir(root,fileSizes)
+		}
+		close(fileSizes)
+	}()
+
+	var nfiles,nbytes int64
+	for size := range fileSizes {
+		nfiles++
+		nbytes += size
+	}
+	printDU(nfiles,nbytes)
+
+}
+
+func printDU(nfiles, nbytes int64) {
+	fmt.Printf("%d files, %.1f GB\n",nfiles,float64(nbytes)/1e9)
+}
+
+func WalkDir(dir string, fileSizes chan <- int64) {
+	for _, entry := range dirents(dir) {
+		if entry.IsDir() {
+			subdir := filepath.Join(dir,entry.Name())
+			WalkDir(subdir,fileSizes)	
+		} else {
+			size,_ := entry.Info()
+			fileSizes <- size.Size()
+		}
+	}
+}
+
+func dirents(dir string) []os.DirEntry{
+	entries, err := os.ReadDir(dir)
+	if err != nil {
+		fmt.Fprintf(os.Stderr,"du1: %v\n",err)
+		return  nil
+	}
+	return entries
+}