Question: Is there an equivalent to the yum "whatprovides" option in apt-get? 

For example on CentOS

```
yum whatprovides /usr/share/gdm/themes/TreeFlower/background.png

```

Tells me 

```
redhat-logos-4.9.99-11.el5.centos.noarch : CentOS-related icons and pictures.
Repo        : base
Matched from:
Filename    : /usr/share/gdm/themes/TreeFlower/background.png

```

Can I get similar functionality on the command line in Ubuntu?

Answer: 
This depends on whether the package containing the file is already installed. If so, use `dpkg -S filename`.

If your intention is to find out which package to install to get a certain file, one option is to use the online [packages.ubuntu.com](http://packages.ubuntu.com/): scroll down to "Search the contents of packages". Make sure that the right distribution is selected. If you're looking for a files irrespective of the path, check the appropriate option.

There is also [`apt-file`](https://wiki.ubuntu.com/AptFile). Because this method required updating the files database, however, I prefer the other, instant option.
`wajig whichpkg /usr/share/gdm/themes/TreeFlower/background.png`

You'll have to install wajig, which is a frontend to a bunch of utilities related to apt. If you use wajig, you can use all of those tools without having to memorize their names.