When can どうも be used as 'hello'?


I noticed this on few occasions. Unfortunately, I can't remember exact
situations.

I want to clarify if どうも in a role of 'hello' is a shortened version of some
longer phrase or just a phrase on its own. When is it okay to use it? Does it
have any hidden nuance?




In case you don't want to or can't read the article Yang linked to, it begins
by quoting two senses listed in the [日本国語大辞典]{にほんこくごだいじてん} which I will
reproduce here in Japanese and translation:

> ④感謝したり詫びたりする気持ちを含む挨拶（あいさつ）に用いる。内容も省略し、「どうもどうも」と重ねて用いることも多い。（以下、用例略。）
>
> ⑤あいまいな、または安易な挨拶のことばとして用いる（以下、用例略。）

And my translation:

> (4) Used as a greeting that include feelings of gratitude and apology.
> Frequently, both the contents [for which one is grateful or apologizing] are
> omitted and the word is repeated as "dōmo dōmo" (following usage examples
> omitted). (5) Used as a greeting ambiguously or lightly.




In case you don't want to or can't read the article Yang linked to, it begins
by quoting two senses listed in the [日本国語大辞典]{にほんこくごだいじてん} which I will
reproduce here in Japanese and translation:

> ④感謝したり詫びたりする気持ちを含む挨拶（あいさつ）に用いる。内容も省略し、「どうもどうも」と重ねて用いることも多い。（以下、用例略。）
>
> ⑤あいまいな、または安易な挨拶のことばとして用いる（以下、用例略。）

And my translation:

> (4) Used as a greeting that include feelings of gratitude and apology.
> Frequently, both the contents [for which one is grateful or apologizing] are
> omitted and the word is repeated as "dōmo dōmo" (following usage examples
> omitted). (5) Used as a greeting ambiguously or lightly.

