From: ni ed <lists@...>
Date: 2012-10-08T14:44:01+09:00
Subject: How to edit a specific line in a file, without using a temp file?

How to edit a specific line in a file? Writing it to a temporary file
and then replace the original file works. However, I need to edit the
file quite often and therefore prefer to do it using just 1 file.

Tried something similar to the following, but this replaces some
characters. (My intention is, if a line includes the string "my query"
then modify that line to be "my query,1")

File.open('mydata.csv', 'r+') do |file|
  file.each_line do |line|
    if line.include?"my query"
      file.seek(-line.length, IO::SEEK_CUR)
      file.puts ',1'
      break
    end
  end
end

Any suggestions are welcome.

Thank you

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