Golang : Find and replace data in all files recursively

Alright, this tutorial is an enhancement of previous tutorial on how to search for file recursively with wildcard support. In this tutorial, we will search for files that matches the search criteria and replace data inside the files with replacement data. Kinda like refactoring.

Here you go!

 package main

 import (
  "bytes"
  "fmt"
  "io"
  "io/ioutil"
  "math/rand"
  "os"
  "path/filepath"
  "time"
 )

 var (
  targetFolder string
  targetFile string
  searchData string
  replaceData  string
  searchResult []string
 )

 func findFile(path string, fileInfo os.FileInfo, err error) error {

  // recording in progress ticker. From good old DOS days.
  ticker := []string{
 "-",
 "\\", //<--- need escape
 "/",
 "|",
  }
  rand.Seed(time.Now().UnixNano())

  if err != nil {
 fmt.Println(err)
 return nil
  }

  // get absolute path of the folder that we are searching
  absolute, err := filepath.Abs(path)

  if err != nil {
 fmt.Println(err)
 return nil
  }

  if fileInfo.IsDir() {
 //fmt.Println("Searching directory ... ", absolute)
 fmt.Printf("\rSearching and replacing data in file(s) .... [%v]", ticker[rand.Intn(len(ticker)-1)])

 // correct permission to scan folder?
 testDir, err := os.Open(absolute)

 if err != nil {
 if os.IsPermission(err) {
 fmt.Println("No permission to scan ... ", absolute)
 fmt.Println(err)
 }
 }
 testDir.Close()
 return nil
  } else {
 // ok, we are dealing with a file
 // is this the target file?

 // yes, need to support wildcard search as well
 // https://www.socketloop.com/tutorials/golang-match-strings-by-wildcard-patterns-with-filepath-match-function

 matched, err := filepath.Match(targetFile, fileInfo.Name())
 if err != nil {
 fmt.Println(err)
 }

 if matched {
 // yes, add into our search result
 add := "Found : " + absolute
 searchResult = append(searchResult, add)
 add = "Creating backup copy of " + absolute

 originalFile, err := os.Open(absolute)
 if err != nil {
 fmt.Println(err)
 }
 defer originalFile.Close()

 searchResult = append(searchResult, add)
 backup := absolute + ".bak"

 backupFile, err := os.Create(backup)
 if err != nil {
 fmt.Println(err)
 }
 defer backupFile.Close()

 // do the actual work
 _, err = io.Copy(backupFile, originalFile)
 if err != nil {
 panic(err)
 }

 add = "Backing up to " + backup
 searchResult = append(searchResult, add)

 //covert *os.File to []byte
 originalFileBytes, _ := ioutil.ReadFile(absolute)

 // ok, now we want to replace the data inside the file
 replaced := bytes.Replace(originalFileBytes, []byte(searchData), []byte(replaceData), -1)

 if err = ioutil.WriteFile(absolute, replaced, 0666); err != nil {
 panic(err)
 }

 add = "Successfully replaced the target data with replacement data"
 searchResult = append(searchResult, add)

 }
  }

  return nil
 }

 func main() {
  if len(os.Args) != 5 {
 fmt.Printf("USAGE : %s <target_directory> <target_file> <search> <replace> \n", os.Args[0])
 os.Exit(0)
  }

  targetFolder = os.Args[1]
  targetFile = os.Args[2]
  searchData = os.Args[3]
  replaceData = os.Args[4]

  fmt.Println("Searching for [", targetFile, "]")
  fmt.Println("Starting from directory [", targetFolder, "]")
  fmt.Println("Replacing [", searchData, "] with [", replaceData, "]")


  // sanity check
  testFile, err := os.Open(targetFolder)
  if err != nil {
 fmt.Println(err)
 os.Exit(-1)
  }
  defer testFile.Close()

  testFileInfo, _ := testFile.Stat()
  if !testFileInfo.IsDir() {
 fmt.Println(targetFolder, " is not a directory!")
 os.Exit(-1)
  }

  err = filepath.Walk(targetFolder, findFile)

  if err != nil {
 fmt.Println(err)
 os.Exit(-1)
  }

  // display our search result
  fmt.Println("\n@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@")

  for _, v := range searchResult {
 fmt.Println(v)
  }

 }

Sample usage:

Let's replace all the "FileSystem" words in ALL the file.go files found in ALL the sub-directories under /Users/sweetlogic

./main ../. file.go "FileSystem" "SystemFile"

Searching for [ file.go ]

Starting from directory [ ../. ]

Replacing [ FileSystem ] with [ SystemFile ]

Searching and replacing data in file(s) .... [-]

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

Found : /Users/sweetlogic/.go/src/golang.org/x/net/webdav/file.go

Creating backup copy of /Users/sweetlogic/.go/src/golang.org/x/net/webdav/file.go

Backing up to /Users/sweetlogic/.go/src/golang.org/x/net/webdav/file.go.bak

Successfully replaced the target data with replacement data

Inspecting the /Users/sweetlogic/.go/src/golang.org/x/net/webdav/file.go file will show that the word FileSystem replaced by SystemFile.

Hope this helps and happy coding!

References:

https://www.socketloop.com/tutorials/golang-command-line-ticker-to-show-work-in-progress

https://socketloop.com/tutorials/golang-simple-file-scaning-and-remove-virus-example

https://socketloop.com/tutorials/golang-search-folders-for-file-recursively-with-wildcard-support