# see https://stackoverflow.com/a/36769049/17860466 Jekyll::Hooks.register :posts, :pre_render do |post| # get the current post last modified time modification_time = File.mtime( post.path ) # inject modification_time in post's datas. post.data['last-modified-date'] = modification_time end Jekyll::Hooks.register :repo, :pre_render do |repo| # get the current post last modified time modification_time = File.mtime( repo.path ) # inject modification_time in post's datas. repo.data['last-modified-date'] = modification_time end