RPM takes special care with a user's config files. By using MD5 checksums, RPM can determine what action is most appropriate with a config file. If a config file has been modified by the user and has to be replaced, it is saved. That way a user's modifications are never lost.

9.4.3. Powerful Query Capabilities

RPM uses a database to keep track of all files it installs. RPM's database provides other benefits, such as the wide variety of information that can be easily retrieved from it. RPM's query command makes it easy for users to quickly answer a number of questions, such as the following:

• Where did this file come from? Is it part of a package?
• What does this package do?
• What packages are installed on my system?

These are just a few examples of the many ways RPM can provide information about one or more packages on a user's system.

9.4.4. Easy Package Verification

Another way that RPM leverages the information stored in its database is by providing an easy way to verify that a package is properly installed. With this capability, RPM makes it easy to determine, for example, what packages were damaged by a wildcard delete in /usr/bin. In addition, RPM's verification command can detect changes to file attributes, such as a file's permissions, ownership, and size.

9.5. To Summarize

RPM was written by developers for developers. It makes building packages as easy as possible, even if the software being packaged hasn't been developed in-house. In addition, RPM presents some significant advantages to users, thereby reducing support needs.

Chapter 10, "The Basics of Developing with RPM," introduces the basic concepts of package building with RPM.