Call File.readlines (or equivalent) on zipped files WITHOUT unzipping them first

I'm trying to write a rake task to scan through some zipped up log files and extract some data that i can then use to update 开发者_StackOverflow中文版some database records. Because of space limitations on our server i can't unzip all of the files and just call File.readlines on them which is what i would normally do.

Can anyone suggest an alternative approach that doesn't involve unzipping the files? What i need to do is basically scan for lines matching a particular regex, then extract some text from the line AFTER the matched line. They are all gzipped, and are therefore .gz files.

You can open the gzipped file using Ruby, and perform your searching as if you had opened the file as normal, like this:

require 'zlib'

Zlib::GzipReader.open("myfile.gz") { |gz|
  # place your code here, something like:
  p gz.readlines.grep /my-magic-marker/
}

This will load the entire file in memory, beware of that.