re = /(?:\/)(?!.*changelogs)(?:\/[^\/]+)*\/(\d+)\/{0,1}/mi
str = 'http://www.opera.com/docs/changelogs/unified/1215/
http://www.opera.com/docs/changelogs/anythingelse/anything/1215/
http://www.opera.com/security/advisory/1047
http://www.opera.com/security/advisory/1048/
http://www.opera.com/doesnt/matter/could/be/anything/1049/
http://www.opera.com/docs/changelogs/unified/1288/
'
# Print the match result
str.scan(re) do |match|
puts match.to_s
end
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Ruby, please visit: http://ruby-doc.org/core-2.2.0/Regexp.html