Flexible redirects dynamically update URLs that have a certain structure, while keeping certain parts of the original URL structure intact. In the URL redirects tool, you can define the components that you want to add to the destination URL.
If your original URL structure contained a common pattern such as a date that you wanted to include in the destination URL, you could use a flexible URL redirect.
Example URL: http://www.example.com/2012/12/30/my-first-post
Original URL: http://www.example.com/:year/:month/:day/:post-name
Redirect to: http://blog.example.com/{month}/{day}/{year}/{post-name}
After saving this flexible redirect, the example URL would redirect to: http://blog.example.com/12/30/2012/my-first-post.
Sometimes you may want to make the entire end (up until a query string) of a URL one component.
Example URL: http://www.example.com/product-id/22/jet-ski
Original URL : http://www.example.com/product-id/*rest-of-url
Redirect to: http://info.example.com/products/{rest-of-url}
After saving this flexible redirect, the example URL would redirect to: http://info.example.com/products/22/jet-ski.
Example URL: http://www.example.com/blog/12/25/2013/marketing/merry-christmas?post-id=33
Original URL: http://www.example.com/blog/:month/:day/:year/*rest-of-url?post-id=:post-id
Redirect to: http://blog.example.com/{month}-{day}-{year}/post-{post-id}/{rest-of-url}.
After saving this flexible redirect, the example original URL would redirect to: http://blog.example.com/12-25-2013/post-33/marketing/merry-christmas.