I've got a virtual hosting of my Rails web-site and i have to determine kind of server, that functions as front-finish.

They are saying, that Apache sits dormant like a front-finish server, but i have to check it in some way.

Is possible ? Maybe some terminal command ?

Basically understand your question correction, you are attempting to look for the kind of web server that's serving your files, correct? If that's the case, make use of a tool like Fiddler (a stand-alone free software application) or FireBug (free plug-set for Opera) to see the HTTP reactions from the server. Generally you will notice an HTTP header known as "Server" that consists of an account from the server getting used. For instance (from cnn.com):

HTTP/1.1 200 OK
Date: Mon, 04 Apr 2011 04:24:46 GMT
Expires: Mon, 04 Apr 2011 05:21:59 GMT
Last-Modified: Fri, 29 Oct 2010 13:42:35 GMT
Cache-Control: max-age=3600
Content-Type: application/x-javascript
Accept-Ranges: bytes
**Server: Apache**
Content-Length: 1907

...or another example, from brinkster.com:

HTTP/1.1 200 OK
Date: Mon, 04 Apr 2011 04:28:02 GMT
**Server: Microsoft-IIS/6.0**
Set-Cookie: BrinksterM1=2; HttpOnly
X-Powered-By: ASP.NET
Cache-Control: private
Content-Type: text/html; charset=utf-8
Content-Length: 44943

You might get specific versions, etc. from the server--it is dependent on which information the server provides--but it might be a really quick, free way method to check and would most likely be the initial step I'd take.