I'm interested to know whether the user-agent is "Chrome" at the server end using PHP. Is there a reliable regular expression for parsing out the user-agent string from the request header?
At this point, too many browsers are pretending to be Chrome in order to ride on its popularity as well as combating abuse of browser detection for a simple match for "Chrome" to be effective anymore. I would recommend feature detection going forward, but Chrome (and WebKit/Blink in general) is notorious for lying to feature detection mechanisms as well, so even that isn't as great as it's cracked up to be anymore either.
I can only recommend staying on top of things by comparing its known UA strings with those of other browsers through third-party sites, and creating patterns from there. How you do this depends entirely on the strings themselves. Just keep in mind that due to the nature of browsers, and UA strings, there can never be a "reliable" regular expression for matching them.
In PHP, the relevant server var is $_SERVER['HTTP_USER_AGENT']
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