Everything you can do with RPM you can program in C. That’s because the source code for the entire RPM system is available. In addition, the rpm and rpmbuild programs make use of a published API, called rpmlib, to access RPM functionality. You can use this library yourself.

The popt library, short for parse options, provides a lot of handy utilities for parsing very complex command-line options. You can use popt inside your own programs, even if you don’t use the rest of the RPM functionality.

Most RPM programs start up by calling rpmcliInit, which sets up RPM variables for the large set of command-line options supported by most RPM commands.

Call rpmReadPackageFile to read in the Header object from a package file. You can also get Header objects for the packages installed in a system by initializing an iterator to iterate over a set of packages that meet a certain criteria.

This chapter covers a fairly low level of access to RPM functionality. The next chapter, on Python programming, shows a higher level of abstraction for working with RPM.