Create an empty file of certain size

ruby-talk
1

Hi,

I need to create an empty (or at least garbage) file of a certain size.
I'm doing it the way below, but it is rather slow -- any ideas on a
quicker way?

  File.open("tmp.txt", 'w') { |f| 10.megabytes.times { f.write "a" } }

Thanks!

~ Mark

···

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2

fd.truncate( 2 ** 20 )

a @ http://codeforpeople.com/

···

On May 15, 2008, at 4:09 PM, Mark Dodwell wrote:

Hi,

I need to create an empty (or at least garbage) file of a certain size.
I'm doing it the way below, but it is rather slow -- any ideas on a
quicker way?

File.open("tmp.txt", 'w') { |f| 10.megabytes.times { f.write "a" } }

Thanks!

~ Mark

--
we can deny everything, except that we have the possibility of being better. simply reflect on that.
h.h. the 14th dalai lama

1 Like
3

fd.truncate( 2 ** 20 )

Thanks that's great, didn't know about that method!

···

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4

If it does not work on your platform, you can speed up your solution
by writing larger chunks:

BUFFER = ("a" * 1024).freeze
File.open("tmp.txt", 'wb') { |f| 10.kilobytes.times { f.write BUFFER } }

Kind regards

robert

···

2008/5/16 Mark Dodwell <seo@mkdynamic.co.uk>:

fd.truncate( 2 ** 20 )

Thanks that's great, didn't know about that method!

--
use.inject do |as, often| as.you_can - without end

5

Robert Klemme wrote:

···

2008/5/16 Mark Dodwell <seo@mkdynamic.co.uk>:

fd.truncate( 2 ** 20 )

Thanks that's great, didn't know about that method!

If it does not work on your platform, you can speed up your solution
by writing larger chunks:

BUFFER = ("a" * 1024).freeze
File.open("tmp.txt", 'wb') { |f| 10.kilobytes.times { f.write BUFFER } }

Here is another way:

size = 2**30
File.open("tmp.txt","wb"){|f|f.seek(size-1);f.write("\0")}

Regards,

Park Heesob
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