restore lost git commits

gistfile1.rb

#!/usr/bin/env ruby

# Helps recovering lost commits, eg when you've:
# - dropped a stash
# - reset a branch to an earlier commit, dropping the changes with --hard
#
# Shows which files have been changed in which dangling commit and prints
# the commands to view details of and restore a commit.
#
# When given a parameter, only lists commits that changed a file matching
# the parameter.
#
# see:
# - http://stackoverflow.com/questions/89332/recover-dropped-stash-in-git
# - http://freeasinbeard.org/post/318519782/reflog-and-fsck-your-git-disaster-recovery-toolkit
# - http://progit.org/book/ch9-7.html

changed_file = ARGV[0]
puts "searching for changes in file #{changed_file}" if changed_file

dangling_commits = `git fsck | awk '/dangling commit/ {print $3}'`.strip.split
dangling_commits.each do |rev|
  show = `git stash show #{rev} 2>/dev/null`
  if changed_file.nil? || show =~ /#{changed_file}/
    puts
    puts "CHANGES in dangling commit #{rev}:"
    puts show
    puts "view details with:  `git stash show -v #{rev}`"
    puts "restore with:       `git stash apply #{rev}`"
  end
end