simple ruby git changelog generator

rake task

  # simple rake task to output a changelog between two commits, tags ...
  # output is formatted simply, commits are grouped under each author name
  #
  desc "generate changelog with nice clean output"
  task :changelog, :since_c, :until_c do |t,args|
    since_c = args[:since_c] || `git tag | head -1`.chomp
    until_c = args[:until_c]
    cmd=`git log --pretty='format:%ci::%an <%ae>::%s::%H' #{since_c}..#{until_c}`

    entries = Hash.new
    changelog_content = String.new

    cmd.split("\n").each do |entry|
      date, author, subject, hash = entry.chomp.split("::")
      entries[author] = Array.new unless entries[author]
      day = date.split(" ").first
      entries[author] << "#{subject} (#{hash})" unless subject =~ /Merge/
    end

    # generate clean output
    entries.keys.each do |author|
      changelog_content += author + "\n"
      entries[author].reverse.each { |entry| changelog_content += "  * #{entry}\n" }
    end

    puts changelog_content
  end

standalone script

#!/usr/bin/env ruby
# output a minimal changelog using git commit first line
# first and second args will be used as "since".."until" args for git log command
# based on http://snipplr.com/view.php?codeview&id=6261
# output is formatted simply, commits are grouped under each author name
#
cmd=`git log --pretty='format:%ci::%an <%ae>::%s::%H' #{ARGV[0]}..#{ARGV[1]}`

entries = Hash.new
changelog_content = String.new

cmd.split("\n").each do |entry|
  date, author, subject, hash = entry.chomp.split("::")
  entries[author] = Array.new unless entries[author]
  day = date.split(" ").first
  entries[author] << "#{subject} (#{hash})" unless subject =~ /Merge/
end

# generate clean output
entries.keys.each do |author|
  changelog_content += author + "\n"
  entries[author].reverse.each { |entry| changelog_content += "\t* #{entry}\n" }
end

puts changelog_content

the git log command has changed since then.

You may want to change the lines:

 #Rake
 #{since_c}..#{until_c}   

 #stand alone
 #{ARGV[0]}..#{ARGV[1]}

To:

 #Rake
 --after=#{since_c} --before=#{until_c}

 #stand alone
 --after=#{ARGV[0]} --before=#{ARGV[1]}

I've got it here in a fork if you want to copy it https://gist.github.com/cdesch/e38af06b4740817de067ba30915d0697