The rules file is what does all the work for actually creating the package. It is a Makefile with targets to compile and install the application, then create the .deb file from the installed files. It also has a target to clean up all the build files so you end up with just a source package again. As the Debian Policy Manual puts it:

This file must be an executable makefile, and contains the
package-specific recipes for compiling the package and building binary
package(s) from the source.

That's nice and all, but what is actually going on here:

%:

    dh $@

dh is a helper command that calls other Make targets and runs a series of debhelper commands. As its manpage describes it:

   dh runs a sequence of debhelper commands. The supported sequences

   correspond to the targets of a debian/rules file: build-arch, build-

   indep, build, clean, install-indep, install-arch, install, binary-arch,

   binary-indep, and binary.

Again, it's just a helper file to simplify things. You don't actually need to use it, but it makes your life much easier. To see what commands are actually run in each target, run:

dh binary-arch --no-act

Now to your specific problem... I don't think it has anything to do with your rules file. Without seeing the actual source package, it is hard to say with certainty what the issue is. Though I'd hazard to guess that there is no binary package stanza in your debian/control file. In the following snippet, the first 'stanza' describes the source package while the second describes the binary package it will build:

Source: hello

Section: devel

Priority: optional

Maintainer: Ubuntu Developers <[email protected]>

XSBC-Original-Maintainer: Jane Doe <[email protected]>

Standards-Version: 3.9.1

Build-Depends: debhelper (>= 7)

Homepage: http://www.gnu.org/software/hello/



Package: hello

Architecture: any

Depends: ${shlibs:Depends}

Description: The classic greeting, and a good example

 The GNU hello program produces a familiar, friendly greeting. It

 allows non-programmers to use a classic computer science tool which

 would otherwise be unavailable to them. Seriously, though: this is

 an example of how to do a Debian package. It is the Debian version of

 the GNU Project's `hello world' program (which is itself an example

 for the GNU Project).