How to convert existing redmine wiki from textile to markdown?

Since this is a once-only task why not pandoc -f textile -t markdown oldfile.text -o newfile.md? Try it at Try Pandoc.

I wrote a rake task to convert all wiki pages and their versions to markdown.

Put this into lib/tasks/convert_textile_to_markdown.rake:

task :convert_textile_to_markdown => :environment do  require 'tempfile'  WikiContent.all.each do |wiki|    ([wiki] + wiki.versions).each do |version|      textile = version.text      src = Tempfile.new('textile')      src.write(textile)      src.close      dst = Tempfile.new('markdown')      dst.close      command = [        "pandoc",        "--no-wrap",        "--smart",        "--strict",        "-f",        "textile",        "-t",        "markdown",        src.path,        "-o",        dst.path,      ]      system(*command) or raise "pandoc failed"      dst.open      markdown = dst.read      # remove the \ pandoc puts before * and > at begining of lines      markdown.gsub!(/^((\\[*>])+)/) { $1.gsub("\\", "") }      # add a blank line before lists      markdown.gsub!(/^([^*].*)\n\*/, "\\1\n\n*")      version.update_attribute(:text, markdown)    end  endend

And run:

bundle exec rake convert_textile_to_markdown RAILS_ENV=production

Building upon Michaël's answer, here is a tool to migrate from Textile to Markdown. It will migrate all content (comment, wiki, issue, message, news, document, project and journal). And it will also fixes several incompatibility between Redmine's Textile and pandoc's.

It's over there: https://github.com/Ecodev/redmine_convert_textile_to_markown