From: Eero Saynatkari <ruby-forum-reg@...>
Date: 2005-12-19T07:03:37+09:00
Subject: Re: Removing parts from a file

Thomas Dutch wrote:
> Hello,
> 
> I'm relatively new to Ruby and I have a question:
> 
> Is it possible to remove one or more lines from a file, without reading 
> the whole file and writing it away again? This because I'll have to do 
> this with files of 1 gigabyte and larger... Is there a high performance 
> solution for this?

You could read the files in small blocks or line per
line and only process that small part at once. I must
say I am not quite sure if ruby internally buffers the
file (though I assume not), so maybe try:

  File.open(fromfile, 'r') {|from|
    File.open(tofile, 'w') {|to|
      if (line = from.gets) == some_condition
        to.puts line
      end
    }
  }

> Thank you!


E

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