path/filepath: add example for Walk

Fixes: #22052

Change-Id: Ia056871b35ecc1a8c5ac891402fc1c5702731623
Reviewed-on: https://go-review.googlesource.com/66330
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/path/filepath/example_unix_test.go

@@ -8,6 +8,7 @@ package filepath_test
 
 import (
 	"fmt"
+	"os"
 	"path/filepath"
 )
 
@@ -79,3 +80,24 @@ func ExampleJoin() {
 	// a/b/c
 	// a/b/c
 }
+func ExampleWalk() {
+	dir := "dir/to/walk"
+	subDirToSkip := "skip" // dir/to/walk/skip
+
+	err := filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			fmt.Printf("prevent panic by handling failure accessing a path %q: %v\n", dir, err)
+			return err
+		}
+		if info.IsDir() && info.Name() == subDirToSkip {
+			fmt.Printf("skipping a dir without errors: %+v \n", info.Name())
+			return filepath.SkipDir
+		}
+		fmt.Printf("visited file: %q\n", path)
+		return nil
+	})
+
+	if err != nil {
+		fmt.Printf("error walking the path %q: %v\n", dir, err)
+	}
+}