Split a file using windows batch script

Question

I have a csv file and i need to split it in to n files such that each split file should not exceed 100 mb. I need to achieve it in windows batch script. I tried the below way but its taking lot of time as my unsplit file is in GBs

@echo off
setlocal enableextensions enabledelayedexpansion
set count=1
set maxbytesize=100000000
set size=1
type NUL > output_1.csv

FOR /F  "tokens=*" %%i in (myfile.csv) do (
FOR /F "usebackq" %%A in ('!filename!_!count!.csv') do (
set size=%%~zA) 
if !size! LSS !maxbytesize! (
echo %%i>>!filename!_!count!.csv) else (
set /a count+=1 
echo %%i>>!filename!_!count!.csv 
))

please let me know if there is a better way to achieve this. I cant go to any other scripting languages as my server is windows

Solution

This would do the trick assuming your lines are roughly the same size.

Its advantage is that it is only a 2 pass solution, One for counting the lines and the other for printing them.

@rem echo off

@rem usage: batchsplit.bat <file-to-split> <size-limit>
@rem it will generate files named <file-to-split>.part_NNN

setlocal EnableDelayedExpansion

set FILE_TO_SPLIT=%1
set SIZE_LIMIT=%2

for /f %%s in ('dir /b %FILE_TO_SPLIT%') do set SIZE=%%~Zs
for /f %%c in ('type "%FILE_TO_SPLIT%"^|find "" /v /c') do set LINE_COUNT=%%c

set /a AVG_LINE_SIZE=%SIZE%/%LINE_COUNT%
set /a LINES_PER_PART=%SIZE_LIMIT%/%AVG_LINE_SIZE%

set "cmd=findstr /R /N "^^" %FILE_TO_SPLIT%"

for /f "tokens=1,2* delims=:" %%a in ('!cmd!') do @(
    set /a ccc = %%a / %LINES_PER_PART%
    echo %%b >> %FILE_TO_SPLIT%.part_!ccc!
)

save it as batchsplit.bat and run it using:

batchsplit.bat myfile.csv 100000000