windows 10 - Rewrite the first three characters of *.ext file names in a folder with a set of letters

How to rewrite the first 3 letters of file name

• Using set alphabet: ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 to randomise characters


• Targeting all files of a particular extension in a folder *.ext


• Duplication of 3 characters by chance does not matter (46,656 variables already)


• Batch script solution to run in a windows environment.


• Prefer script to be simple to reduce run time.

Suggested code and breakdown. Note: I still have no idea how to code.

• 
  

  Original:

  
  

  032_name.ext
  039_name.ext
  0D8_name.ext
  333_other.txt
  



• 
  

  Write Over the top of first three characters

  
  

  XXX-name.ext
  



• 
  

  After

  
  

  D7K_name.ext
  L2V_name.ext
  720_name.ext
  333_other.txt
  

Make batch file (SetRename.bat or SetRename.cmd) then run command like:

SetRename %r *.ext   /or/ SetRename %r3%name% *.ext  /or/ SetRename

• 
  

  Code 1 adapted from DavidPostill, example of full solution

  
  

  @echo off
  setlocal enabledelayedexpansion
  rem initialise counter
  set "alphabet=A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 0 1 2 3 4 5 6 7 8 9"
  rem process jpg and png files
  for /f "usebackq tokens=*" %%i in (`dir /b *.ext *.ex2`) do (
    rem split into name and extension
    set _name=[reduce 3 characters]]%%~ni
    set _ext=%%~xi
    rem do the rename
    ren "%%i" "!y!-!_name!-!_ext!"
    increment counter
    set /alphabet "%Random%"
    )
  endlocal
  



• 
  

  Code 2 adaptated from 3 SU posts

  
  

  @echo off
  
  setlocal enableextensions enabledelayedexpansion
  
  set "alphabet=A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 0 1 2 3 4 5 6 7 8 9"
  
  for %%a in (%alphabet%) do (
      set "a.!name!=%%a"
  set o=-%3 [reduce by 3] 
  
  )   
  set "y="
  for /l %%a in (1 1 3) do (
      set /a "r=!random!"
      for %%b do set "y=!-%3!!r!!name!"
  )
  echo(%y%
  
  endlocal
  

Current Research:

Answer

How can I rewrite the first 3 letters of a set of file names with random characters?

Use the following batch file (SetRename.cmd):

@echo off
setlocal enableDelayedExpansion
set "_chars=ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
for %%f in (%*) do (
  rem split into name and extension
  set "_name=%%~nf"
  rem remove first 3 characters from _name
  set "_name=!_name:~3!"
  set "_ext=%%~xf"
  rem create a 3 character random prefix
  set "_prefix="
  for /l %%n in (1 1 3) do (
    set /a i=!random!%%36
    for %%i in (!i!) do (
      set "_prefix=!_prefix!!_chars:~%%i,1!" (
      )
    )
  echo ren "%%f" "!_prefix!!_name!!_ext!"
  )
endlocal

Notes:

• remove echo when you are happy with the ren command

Example usage:

> dir /b
032_name.ext
039_name.ext
0D8_name.ext
333_other.txt
SetRename.cmd

> SetRename *.ext

> dir /b
333_other.txt
C42_name.ext
FZW_name.ext
MYQ_name.ext
SetRename.cmd

> SetRename *.ext

> dir /b
333_other.txt
A6O_name.ext
A8H_name.ext
H5P_name.ext
SetRename.cmd

---

Further Reading