In English you might say, hey man, hey mate, hello there etc. depending on your preference (and often age, social background, region etc.) What are some similar constructions in Brazilian Portuguese?
Brazil is a very large country, larger than the continental US. It's just natural that we should have different ways in different places. More than that, within a same metropolitan area forms of greeting and address also vary according to scoioeconomic and educational level.
In Southeastern Brazil, you may well hear:
- Oi, cara, tudo bem? (very informal)
- Aí mermão, tranquilo? (very informal and slangy, ("mermão" being a junction of "meu + irmão")
- Fala aí, meu! ("meu" is the same as "cara" (mate, buddy) It's not heard in Rio de Janeiro but it's quite common in São Paulo.
- Aí, brother, cuméquié? (Hi, brother, how are you doing. "cuméquié" is a junction of words ("como é que é). This greeting sounds like the speaker is uneducated.
- "Oba, amigão, tudo tranquilo? (hi, my friend, everything fine?) This one shows some intimacy, you know the person well.
- "Eae mano" ( What's up bro*¹ ) "Eae" stands for "E + Aí" , which means "How's there?" . *¹ is an abbreviation for "brother" .
In the Brazilian Northeast, you can hear:
- "Colé parceiro , tudo beleza? (What's up partner, everything fine?) Extremely informal , "Colé" means "Qual é?" , "parceiro" stands for "mate" , also "tudo beleza" is equal to "everything fine?".
All of these are really very informal. Not to run the risk of being labeled gross, I suggest you use "bom dia/tarde/noite, fulano/a,sr/sra fulano/a, como vai?" when you address somebody you've seen only a few times.
PS Just like in any other language, you don't expect the person to tell you what their life has been like when you ask "Como vai, sr/sra fulano/a?"
As requested by @Some_guy, I expanded my short comment in an answer:
Although I've visited several cities from almost every state of Brazil, I cannot list all regional greetings, they're "endless". So, I'll list greetings that we can hear in São Paulo, but as São Paulo is a big cosmopolitan city and so it has a great mix of culture from all corners of Brazil and from the world, there is a good chance of being known and used all over Brazil.
NOTE: The expressions with bad language, is used only when the person is very intimate, or the opposite, when you want to be very rude with someone (or them).
E aí "somebody" ! : Any noun or person names can be joined with "E aí...", some: E aí meu ! E aí truta ! E aí cabra da peste ! E aí maluco ! E aí filho da puta ! E aí seus cuzão ! E aí carinha ! E aí bicho ! E aí véi ! E aí mano !
Beleza "somebody" !? : Used as exclamation and/or question and can be joined also with nouns or persons names, like: Beleza Zezinho ? Beleza meu ? Beleza cara ? Beleza mano !? Tudo beleza ? ...
The shorten version Belê !? is derived from "beleza". And is more commonly used alone, so without joining anything to it.
Fala "somebody" ! : Very old and very common in every corner of Brazil, some examples: Fala ! Fala bicho ! Fala carinha ! Fala mano ! Fala seu cabra da peste ! Fala aí truta ! Fala meu ! Fala brôu ! Fala aí seu viadinho ! Fala aí seu tanga frouxa ! ...
Tudo certo ? or Certinho !? : Used as exclamation and/or question. Used also when persons say goodbye. Examples: Tudo certo aí ? Tudo certo brôu !? Certinho !? Certinho aí maluco ? Certinho aí brôu ? ...
A lot of mixing (maybe endless) can be done, and as showed by the answer of @Centaurus, all them can be combined and added with more expressions or phrases usually after the greetings:
- E aí ! Belê ?
- Fala meu, beleza !? or Fala meu ! Beleza ?
- Tudo bem ? Belê ?
- Tudo bem ? Certinho ?
- Fala ae mano, tranquilo ?
- Eae, tudo na paz ?
- Tudo em riba ?
- Tudo em cima ?
Nowadays, at least in São Paulo, I hear more often 3 of them (of course, can be mixed and added with more phrases):
- E aí ! (very informal but very common)
- Beleza ? (very informal but very common)
- Tudo bem ? (neutral, used in every situation, even formal)
I suggest to foreigners or learners of Portuguese to use only: Olá ! Como vai ? Tudo bem ? All or a mix of them. Leave all others in a side of your vocabulary just to understand what natives speak. Let the coexistence with natives naturally lead you to use others as a more intimate response to how they talk to you.
- "brôu" is a shortening of brother (from english);
- "véi" is a shortening of "velho". The first uses of "velho" that I remember was like "E aí meu velho ! Tudo bem ?" "Fala meu velho !" where "velho" was used with a lot of respect and intimate to persons like your father, grandfather, a professor, your master, or any kind of person you have a lot of respect and intimate, like as: Bom dia meu velho amigo! Como vai meu velho e saudoso mestre? But nowadays, at least when it's said "véi" it doesn't carries anymore these tons of respect, it's just like a "dude", "guy"...