Batch Insert the line number in each line

Question

I have a little problem and can not get on right now. I would like to batch import a .txt file and output this with line numbers to another .txt. For example, the test.txt file looks like this:

hello
how 
are 
you

The result should be the file test2.txt and look like this:

1: hello
2: how
3: are
4: you

I have tried the following batch but unfortunately I only get an empty file as output:

@echo off
setlocal enabledelayedexpansion
findstr / n; test.txt >test2.txt

Does anyone have an idea? Thanks in advance!

Answer 1

This version will do write from test.txt to test2.txt:

@echo off
setlocal enabledelayedexpansion

set "myfile=test.txt"
set "outputfile=test2.txt"

for /f "tokens=*" %%a in ('type "%myfile%" ^| find /v /n "" ^& break ^> "%myfile%"') do (
     set "str=%%a
     set "str=!str:]=: !"
     set "str=!str:[=!"
     >>%outputfile% echo(!str!
  )

This version will write back to the original file, test.txt and write back to test.txt, thus overwriting it:

@echo off
setlocal enabledelayedexpansion

set "myfile=test.txt"

for /f "tokens=*" %%a in ('type "%myfile%" ^| find /v /n "" ^& break ^> "%myfile%"') do (
     set "str=%%a
     set "str=!str:]=: !"
     set "str=!str:[=!"
     >>%myfile% echo(!str!
  )

Which will do what you want:

1: hello
2: how 
3: are 
4: you

Note, this will also number \n in other words new empty lines. So for instance, if you have:

hello

how 
are 
you

It will result in:

1: hello
2:
3: how 
4: are 
5: you