What do British people mean by greeting you with "You okay?"?

Same thing those of us in California mean when we say it. It’s a short form of asking if you are doing alright.

i haven’t heard this as a Britishism.

As far as I know, British people don’t use that as a greeting.
I’m British and I only use that if I want to know exactly what the terms suggests.
“Is the person okay and well?”. It’s usually after the person says or does something out of character or is upset.

@zenvelo & @MilkyWay, That’s what I originally thought, but for example, someone on Facebook messaged me saying “Hey, you okay?” and I’ve never talked to him before (though we have mutual friends), or given him anything to suggest that I wouldn’t be okay. So I just thought maybe that was a way for him to start a conversation, and that it must be a British thing. :P

I’m used to hearing “All right?” as an English greeting, but remember being thrown when I heard the Australian “How’re you going?” for the first time, which I guess falls somewhere between “how are you doing?” and “how’s it going?”

@ChocolateCoveredStarfish Nah, that sounds like he legitimately wants to know if you are okay. Maybe you’ve posted a sad-sounding status recently?

I’m British too orginally and like @MilkyWay, I have never heard “You okay?” used as a greeting.

In Sierra Leone, a common greeting among friends is “How’s de body?”

I’m in Canada and that’s a normal expression where I live. I think it is usually used within a certain context ..not a certain nationality.

I think it’s said after hello. Like the British equivalent of wassup.

I say it every so often when greeting someone I know. It is the same as saying “how are you?”

We use it in New Zealand too. Simply another way of saying ’ how’s it going ’