How to use regex in selenium locators

A possible solution is to use sel.get_eval() and write a JS script that returns a list of the links. something like the following answer: selenium: Is it possible to use the regexp in selenium locators

You can use the Selenium command getAllLinks to get an array of the ids of links on the page, which you could then loop through and check the href using the getAttribute, which takes the locator followed by an @ and the attribute name. For example in Java this might be:

String[] allLinks = session().getAllLinks();
List<String> matchingLinks = new ArrayList<String>();

for (String linkId : allLinks) {
    String linkHref = selenium.getAttribute("id=" + linkId + "@href");
    if (linkHref.matches("http://[^/]*\\d+.com")) {
        matchingLinks.add(link);
    }
}

The answer above is probably the right way to find ALL of the links that match a regex, but I thought it'd also be helpful to answer the other part of the question, how to use regex in Xpath locators. You need to use the regex matches() function, like this:

xpath=//div[matches(@id,'che.*boxes')]

(this, of course, would click the div with 'id=checkboxes', or 'id=cheANYTHINGHEREboxes')

Be aware, though, that the matches function is not supported by all native browser implementations of Xpath (most conspicuously, using this in FF3 will throw an error: invalid xpath[2]).

If you have trouble with your particular browser (as I did with FF3), try using Selenium's allowNativeXpath("false") to switch over to the JavaScript Xpath interpreter. It'll be slower, but it does seem to work with more Xpath functions, including 'matches' and 'ends-with'. :)