hgrep - historic grep. Find the last version where some string occurred in a file in a git repository.

hgrep.rb

#!/usr/bin/env ruby

if ARGV.length < 2
  puts "#{File.basename(__FILE__)} file pattern [grep options]"
  exit 1
end

`git reflog #{ARGV[0]}`.split("\n").each do |ref|
  oid = ref.split(" ").first
  if `git cat-file -p #{oid}:#{ARGV[0]} | grep #{ARGV[1]}` != ""
    puts "Found match for '#{ARGV[1]}' in #{oid}:#{ARGV[0]}"
    puts `git cat-file -p #{oid}:#{ARGV[0]} | grep #{ARGV[2..-1].join(' ')} #{ARGV[1]}`
    exit 0
  end
end

puts "No match for '#{ARGV[1]}' in #{ARGV[0]}"
exit 1