From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2011-07-20T15:40:05+09:00
Subject: Re: copy range of lines to another file based on regex match

On Wed, Jul 20, 2011 at 7:18 AM, Neubyr Neubyr <neubyr@gmail.com> wrote:
> Hi,
>
> I am writing a script to search for a particular string in a file and
> then copy all lines starting from matching-line to another file.
> Following should make it clear again:
> * search for first occurrence of a particular string in a file
> * find it's line number
> * copy certain text in all lines or entire line, starting from above
> line number to EOF to another file
>
> I can find the matching line's number as:
> <code>
> File.foreach(afile) do |line|
>  if line =~ /(\S+:)(\S+:)(\S+:)8055:(\S+:)(\S+)/
>    puts "Found match at #{$.}"
>    lnumber = $.
>  end
> end
> </code>
>
> But I am not sure how to copy range of line numbers to another file. I
> thought about using another File open again and then use range operators
> ($. == lnumber) as mentioned here,
> http://pleac.sourceforge.net/pleac_ruby/patternmatching.html , but
> wondering if there is any other better way that I might be missing here.
> Any suggestions?

Forget about line numbers, you are already iterating over the lines,
just iterate first until that line, then read the rest of the file and
write it out:

File.open(file) do |f|
  File.open(output, "w") do |out|
  line = f.gets until line =~ your_regex
  out.puts line
  out.write f.read
end

Jesus.