Is "How are you?", when used as a greeting, an idiom? Is there a better word for it? [closed]

When passing someone in the hall, you might say "How are you?" as a greeting, but not meaning it literally, as you don't really require an answer. Is "How are you?" (or "How's it going?", etc.) an idiom when used this way?

"Idiom" doesn't seem appropriate because that combination of words generally has the literal meaning. Is there another word for this?

Sorry if I am not making this clear. If I can clarify in some way, please ask.

Edit: Could someone explain why this question might have been voted down? Not complaining, just trying to learn.

Solution 1:

It's a phatic expression:

a phatic expression /ˈfætɨk/ is one whose only function is to perform a social task, as opposed to conveying information

Solution 2:

Idioms typically have meanings completely unrelated to the literal interpretation of words. This might not apply to “How are you?”, as its use as a greeting can be arguably be deduced from the words themselves.

However, the phrase is definitely idiomatic, being an expression (ie. not interpreted literally) that would seem natural to a native speaker.