Replace some text in a bunch of files with golang

walk.go

package main

import (
	"fmt"
	"io/ioutil"
	"os"
	"bufio"
	"path/filepath"
	"strings"
)

//https://gist.github.com/tdegrunt/045f6b3377f3f7ffa408
func visit(path string, fi os.FileInfo, err error) error {
	if err != nil {
		return err
	}
	if !!fi.IsDir() {
		return nil //
	}
	matched, err := filepath.Match("*.php", fi.Name())
	if err != nil {
		panic(err)
		return err
	}
	if matched {
		read, err := ioutil.ReadFile(path)
		if err != nil {
			panic(err)
		}
		newContents:= string(read)
		for i, _ := range toReplace {
			newContents = strings.Replace(newContents, oldKwords[i],  newKwords[i], -1)		
		}
		fmt.Println("Changed ", path)
		
		err = ioutil.WriteFile(path, []byte(newContents), 0)
		if err != nil {
			panic(err)
		}
	}
	return nil
}

//https://gist.github.com/kendellfab/7417164
func readLine(path string) []string {
	var temp []string
  inFile, _ := os.Open(path)
  defer inFile.Close()
  scanner := bufio.NewScanner(inFile)
	scanner.Split(bufio.ScanLines) 
  for scanner.Scan() {
		temp = append(temp, scanner.Text())
  }
	return temp
}

func main() {
	oldKwords := readLine("old.txt")
	newKwords := readLine("new.txt")
	
	err := filepath.Walk(".", visit)
	if err != nil {
		panic(err)
	}
}