re = /(?<=utm_campaign=\w*)[^_]+/
str = 'www.sitename.com.au/landing-page?utm_source=facebook&utm_medium=social&utm_campaign=fruit_apples_kids'
# 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