Golang : Scan files for certain pattern and rename part of the files

It is useful to have the ability to scan filenames that match certain pattern and rename part of the filenames in a directory. This tutorial builds on from the previous tutorial on how to rename a file with Go.

This program below will first scan the given path for files with matching names and rename the first :

 package main

 import (
 "flag"
 "os"
 "path/filepath"
 "strings"
 )

 var flagPath = flag.String("path", "", "path to walk in search for dumb_* files.")

 func partialrename(path string, f os.FileInfo, err error) (e error) {

 // check each file if starts with the word "dumb_"

 if strings.HasPrefix(f.Name(), "dumb_") {
 base := filepath.Base(path) // get the file's basename
 dir := filepath.Dir(path)

 renameto := filepath.Join(dir, strings.Replace(base, "dumb_", "smart_", 1))
 os.Rename(path, renameto)
 }
 return
 }

 func init() {
 flag.Parse()
 }

 func main() {

 // check if the user specify a path
 if *flagPath == "" {
 flag.Usage() // if no, prompt usage
 os.Exit(0) // and exit
 }

 // walk through the files in the given path and perform partialrename()
 // function
 filepath.Walk(*flagPath, partialrename)
 }

Test output :

ls -la /Users/sweetlogic/testdir

total 0

drwxr-xr-x 5 sweetlogic staff 170 Oct 23 15:13 .

drwxr-xr-x+ 39 sweetlogic staff 1326 Oct 23 15:13 ..

-rw-r--r-- 1 sweetlogic staff 0 Oct 23 15:13 dumb3.txt

-rw-r--r-- 1 sweetlogic staff 0 Oct 23 15:13 dumb_1.txt

-rw-r--r-- 1 sweetlogic staff 0 Oct 23 15:13 dumb_2.txt

and after executing ./renamepartial -path="/Users/sweetlogic/testdir"

ls -la /Users/sweetlogic/testdir

total 0

drwxr-xr-x 5 sweetlogic staff 170 Oct 23 15:14 .

drwxr-xr-x+ 39 sweetlogic staff 1326 Oct 23 15:13 ..

-rw-r--r-- 1 sweetlogic staff 0 Oct 23 15:13 dumb3.txt

-rw-r--r-- 1 sweetlogic staff 0 Oct 23 15:13 smart_1.txt

-rw-r--r-- 1 sweetlogic staff 0 Oct 23 15:13 smart_2.txt

the dumb3.txt file remains the same because its name doesn't match the strings.HasPrefix() patter of "dumb_".

Hope this tutorial can be useful for your work.