extracting specific lines of data from multiple text files, to convert to a single csv file

Question

First, apologies for my poor coding ability, however I have spent a few hours reading the forums and giving it a crack, so I would really appreciate any help with the follow

Answer 1

@echo off
setlocal EnableDelayedExpansion
if exist result.csv del result.csv
for %%f in (*.txt) do (
    set i=0
    for /F "delims=" %%l in (%%f) do (
        set /A i+=1
        set line!i!=%%l
    )
    echo %%f, !line3!, !line5!, !line7! >> result.csv
)

This Batch file process all .txt files in the directory, as you said.

Answer 2

You could read the lines with another construct.

setlocal EnableDelayedExpansion
< %1 (
Set /p line1=

Set /p line2=
Set /p line3=
Set /p line4=
Set /p line5=
Set /p line6=
Set /p line7=
)
Echo %1,!line3!,!line5!,!line7!

Or with a loop (Andriy)

Setlocal EnableDelayedExpansion
<%1 (
  For /L %%n in (1 1 7) do (
    Set /p line%%n=
  )
)
Echo %1,!line3!,!line5!,!line7!