How can I know to which ubuntu package does a specified file (not on my fs) belongs?

[Alan Pope]

On 30 March 2011 22:02, Nils Kassube <kassube at gmx.net> wrote:
> Kevin Wilson wrote:
>> I want to know how can I find (with apt-get), to which ubuntu package
>> does a certain file (which **does not** exist on my filesystem)
>> belong.
>
> AFAIK apt-get doesn't offer that option but you can install the package
> "apt-file". Then run the command
>
> sudo apt-file update
>
> once and after that you can search for individual files with the command
>
> apt-file search filename

I realise the OP asked for a way on the machine to do it
programmatically but also useful is packages.ubuntu.com.

http://packages.ubuntu.com/search?searchon=contents&keywords=crypto.h&mode=exactfilename&suite=maverick&arch=any

Cheers,
Al.