Finalizing The Spec File And Building Your Own Linux RPM

Hey There,

We're finally ready to create our very own Linux RPM package! Following up on yesterday's post regarding beginning to write your spec file and the preceding initial software build, we're now going to look at the "build" section of the RPM spec file and compile our new RPM.

The "build" section of the spec file follows the "header section" we went over previously, and contains all that the "rpmbuild" command needs to know in order to create your RPM for you. I should note here that, on some systems, this command may be called "rpm-build" and, on yet others, the rpmbuild flags may simply be options to the rpm command itself (as with SUSE 8.x)

The declarations required in this section are:

%clean <--- Well, not really required, but keeps things nice and tidy ;)
%prep
%setup
%files
%build
%install

These sections are defined as follows (Note that for these declarations, the values are listed beginning on the line below, rather than on the same line, as we did in the "header section":

%clean - this deletes everything in the RPM_BUILD_ROOT, as defined by either the BuildRoot declaration in the "header section" (Which we didn't use for this build) or by the system default. In our case, this should be /usr/src/packages/BUILD. Cautious users may want to add a line of code in front of this, assuring that the RPM_BUILD_ROOT variable isn't set to /. This method is not absolutely necessary, either, so the incredibly cautious can just not call it and remove old garbage files, whenever they want to, manually. It can also cause issues when running concurrent builds if using the same RPM_BUILD_ROOT! Some folks prefer to run this method at the end of the spec file, or script out what it does automatically. It's a matter of preference :)

%prep - This simply indicates that we're moving on to the next section of our spec file. It is necessary, as everything beyond it will be considered part of the build process, rather than part of the RPM definition process, listed above it.

%setup - This part of the spec file indicates that "rpmbuild" should do whatever is necessary to prepare the source for building/compilation. Of course, we've done this already (to make sure we could build from source properly), but this declaration is necessary so that rpmbuild sets everything up for the following sections. Note that without any arguments, in our setup, it's just going to unzip and untar our source package in /usr/src/packages/SOURCES to the /usr/src/packages/BUILD directory.

%files - This is where we have to list all of the files that are going to be in our RPM, for reference when its installed and/or removed using the "rpm" command. In our previous post on building the software from source, we created a file called FILELIST (from the output of the find command). On the line following the %files declaritive, you can just read that file list into your spec file. If you elect to type each file name in, that's your decision, but you should include only one file per line (which can make your spec file pretty long depending on what you're installing. Given how many files most software packages contain, you'll grow sick and tired of this method soon enough ;)

%build - Here you'll provide all the information required to build the software. This can be culled from the notes you took while compiling the program initially.

%install - And finally, here you'll provide all the information required to install the program (Basically, the "make install" command and all arguments from the original compile of the software that you did earlier.

Our spec file will look something like this:

%clean
%prep
%setup
%files
/usr/local/PACKAGE-3.2-1/bin/list
/usr/local/PACKAGE-3.2.1/lib/liblist.so
...
%build
./configure --prefix=%{prefix}
make
make check
%install
make install
/bin/chown -Rv root:root %{prefix}

Before we actually build our RPM, we'll want to change the names of all the files listed in the %files section, that we got from our initial build. Assuming you wanted the RPM to install in /usr/local, you would want to use your favorite editor to replace all instances of "/usr/local/PACKAGE-3.2-1" in this section with "/usr/local" - this would change our %files section from:

%files
/usr/local/PACKAGE-3.2-1/bin/list
/usr/local/PACKAGE-3.2.1/lib/liblist.so
...

to

%files
/usr/local/bin/list
/usr/local/lib/liblist.so
...

Now our spec file is complete and we can create our RPM using this one simple command: rpmbuild. For our purposes, we'll run:

host # rpmbuild -ba PACKAGE.spec

then we'll kick back and watch the magic happen :) Note that I used the "-ba" option to build both source and binary RPM packages. This created the files /usr/src/packages/SRPMS/PACKAGE-3.2-1.src.rpm and /usr/src/packages/RPMS/x86_64/PACKAGE-3.2-1.x86_64.rpm <--- Note that this directory may be slightly different depending on what OS version of Linux you're running.

Now, you're all set to run "rpm -ivh PACKAGE-3.2-1.x86_64.rpm" and your software package will be installed, and can be manipulated by all the standard "rpm" facilities.

Of course there are tons of other options and additions to the spec file (%post, etc) and rpmbuild command, but this should be enough to get you started. For more specific information, check out the online man pages and chat boards - You'd be surprised at what you can do with this software if you use your imagination :)

Best wishes,

, Mike

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