quickly write a large file?

[taripo]

Hi

How can I quickly write a large file where each line has the string "aaa"?

this method is slow

I let it run for about 20 seconds and stopped it 'cos it was slow and it wrote maybe 20,000 lines far from 200,000

C:\blah>for /L %f in (1,1,200000) do @echo aaa >>abigfile1.txt

I could write a program test.rb in eg ruby

i=0
while i < 200000 do
puts("aaa")
i+=1
end

and run ruby test.rb >bigfile

that runs fast, does the whole task within a second

But ruby is a third party program that not everybody would have installed.

i'm wondering if there is a way to do it without a third party program, that is as fast ore pretty fast like within <= 3 seconds.. That somebody can run and produce that file?

TIA

[penpen]

First, you should avoid creating thousands of filestreams where one filestream suffices:

Code: Select all

(for /L %f in (1,1,200000) do @echo aaa) >>abigfile1.txt

Then you should use a batch file, because if you execute this command in "cmd.exe" you also change the title 400,002 times (in your case).

At last you should avoid many for loop iterations as possible.

So this batch file ("test.bat") might help you:

Code: Select all

@echo off
setlocal enableExtensions disableDelayedExpansion
echo %time%
for %%a in ("abigfile1.txt") do (
	>"%%~a" (for /L %%f in (1,1,3125) do echo aaa)
	for /L %%f in (1,1,6) do >>"%%~a" findstr "^" "%%~a"
)
echo %time%

endlocal
goto :eof

This batch takes round about 0.2 seconds on my system.

penpen

[taripo]

thanks