Given all these differences, how can you create RPMs while avoiding problems? With some work setting things up, you can create an RPM build environment that solves most vendor issues. This depends on taking a methodical approach to building your packages and using techniques to avoid vendor issues wherever possible.
When building RPMs, you will face many of the same problems@@mdand solutions@@mdas when installing RPMs. For example, due to the different ways Linux vendors divide software into packages, your RPMs will likely have issues defining the proper dependencies. There are also a number of issues that apply only when building RPMs.
18.2.1. Writing distribution-specific packages
One of the ways around all the differences between Linux distributions in RPM usage is to define distribution-specific packages. To do this, you create a separate package on each Linux distribution you support.
That’s a lot of work. If possible, fit the differences into macros and use a single spec file to reduce some of this work. This technique works up to a point. Sometimes, your spec file becomes too complicated and you may decide that it is easier to create multiple spec files, one per Linux distribution.
One way to help make vendor-specific packages, or to see which RPM macros are defined on a given Linux distribution, is to look for an RPM that contains the distribution-specific RPM configuration. For example, on Red Hat Linux systems, the Red Hat RPM configuration is defined by the redhat-rpm-config package.
You can list the files in this package to see where Red Hat defines macros specific to their Linux distribution.
$ rpm -ql redhat-rpm-config
/usr/lib/rpm/redhat
/usr/lib/rpm/redhat/brp-compress
/usr/lib/rpm/redhat/brp-redhat
/usr/lib/rpm/redhat/brp-sparc64-linux
/usr/lib/rpm/redhat/brp-strip
/usr/lib/rpm/redhat/brp-strip-comment-note
/usr/lib/rpm/redhat/brp-strip-shared
/usr/lib/rpm/redhat/find-lang.sh
/usr/lib/rpm/redhat/find-provides
/usr/lib/rpm/redhat/find-requires
/usr/lib/rpm/redhat/macros
/usr/lib/rpm/redhat/perl.prov
/usr/lib/rpm/redhat/perl.req
/usr/lib/rpm/redhat/rpmrc
These files, such as /usr/lib/rpm/redhat/macros, show you what is specific to a given Linux distribution. You can then look at the macros defined in these files to identify settings for a particular distribution, in this case, Red Hat. Armed with this knowledge, you can better create portable RPM spec files.
