Add a line in middle of txtfile in cmd

Question

here\'s a text file txtfile.txt

line1
line2
add after this line
line4
etc
etc

i want to create a batch file which can add a li

Answer 1

@ECHO OFF
SETLOCAL
SET /p info="enter info : "
:: read addafter line
(
FOR /f "delims=" %%i IN (poison1.txt) DO (
SET addafter=%%i
FOR /f "delims=" %%n IN (' findstr /n "^" txtfile.txt') DO (
SET line=%%n
SETLOCAL ENABLEDELAYEDEXPANSION
SET line=!line:*:=!
ECHO(!line!
IF "!line!"=="!addafter!" ECHO(%info%
ENDLOCAL
)
)
)>newfile.txt

FC newfile.txt txtfile.txt

GOTO :eof

Where poison1.txt contains the one line

"A line !of! ] many < & >var*ied %poison ^ char;ac(ters) | like "," a\nd+so=on"

and txtfile.txt contains this line.

• Read the line from the poison1.txt file to addafter
• For each line in the add-to-me file
  
  • Number the line to catch empty lines
  • Remove the number and first colon (added by FINDSTR)
  • Output the line verbatim
  • if the line matches the target, output the extra line

done!