Xlsx2xls
The Xlsx2xls ruby library provides an easy way to convert file.xlsx to file.xls.
Installation
Install LibreOffice
$sudo apt-get install libreoffice
Add this line to your application's Gemfile:
gem 'xlsx2xls'
And then execute:
$ bundle install
Or install it yourself as:
$ gem install xlsx2xls
Usage
xls_output_file_name = Xlsx2xls.convert "file_name"