diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..17c3d06
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,7 @@
+.bundle/
+Gemfile.lock
+books.csv
+books/
+index.html
+tmp/
+vendor/
diff --git a/Gemfile b/Gemfile
new file mode 100644
index 0000000..6335331
--- /dev/null
+++ b/Gemfile
@@ -0,0 +1,2 @@
+source 'https://rubygems.org/'
+gem 'gepub'
diff --git a/books.csv.erb b/books.csv.erb
new file mode 100644
index 0000000..3a19787
--- /dev/null
+++ b/books.csv.erb
@@ -0,0 +1 @@
+<% books.each do |b| %>
\ No newline at end of file
diff --git a/index.rb b/index.rb
index eb93c1b..38569b6 100644
--- a/index.rb
+++ b/index.rb
@@ -1,14 +1,28 @@
 require 'gepub'
 require 'erb'
+require 'optparse'
+require 'pathname'
 
 # Parse epubs
 
-books = Dir["books/*.epub"].map do |f|
-  [f, GEPUB::Book.parse(File.new f)]
-end
+options = {:subdir => "books"}
+OptionParser.new do |opts|
+  opts.banner = "Usage: index.rb [options]"
 
-books = books.to_h
+  opts.on("-d", "--dir DIR", "directory to index (subdir specified with '-s' will be indexed)") do |d|
+    options[:dir] = d
+  end
 
+  opts.on("-s", "--subdir DIR", "subdirectory to search for books") do |s|
+    options[:subdir] = s
+  end
+end.parse!
+
+raise OptionParser::MissingArgument unless options[:dir]
+
+books = Dir["#{options[:dir]}/#{options[:subdir]}/*.epub"].map do |f|
+  [Pathname.new(f).relative_path_from(Pathname.new(options[:dir])), GEPUB::Book.parse(File.new f)]
+end.to_h
 
 # Collection of sort_by procs
 
@@ -25,15 +39,32 @@ title_sort_by = proc { |filename, book|
 
 books = books.sort_by &title_sort_by
 
+i = 0
+book_ids = books.map { |filename, book| [filename, i += 1] }.to_h
+i = nil
 
 # Generate 'index.html' from template
 
 bind = binding
 bind.local_variable_set(:books, books)
 
-template = File.read 'index.html.erb'
+html_template = File.read 'index.html.erb'
 
-result = ERB.new(template).result(bind)
-File.open "index.html", "w+" do |f|
-  f << result
+html_result = ERB.new(html_template).result(bind)
+File.open "#{options[:dir]}/index.html", "w+" do |f|
+  f << html_result
+end
+
+
+# Generate 'books.csv'
+
+File.open "#{options[:dir]}/books.csv", "w+" do |f|
+  f << "id\ttitle\tauthor\tfilename\n"
+  books.each do |filename, book|
+    f << "#{book_ids[filename]}\t"
+    f << "#{book.title.content}\t"
+    f << "#{book.creator.content}\t"
+    f << "#{filename}\t"
+    f << "\n"
+  end
 end