Red Hat Enterprise Linux 5 Administration Unleashed

CHAPTER 5Working with RPMSoftwareA large part of a system administrator’s job is to maintainthe software on a company’s servers as well as the softwareon the users’ desktops. This can be a very daunting task,especially for a large corporation. The software must beupdated for security fixes, compatibility with other software,and feature enhancements if they are needed. Before thesoftware updates are applied to production systems, theupdated software must be tested and verified to be compatiblewith the existing programs. To efficiently maintain thesoftware on a Red Hat Enterprise Linux system, Red HatNetwork (RHN) should be used as discussed in Chapter 3,“Operating System Updates.” Red Hat Network is based on asoftware maintenance utility called RPM (Red Hat PackageManager). Entire books have been written on RPM, so thischapter will not attempt to cover every aspect of the softwarepackaging tool. Instead, it gives an overview of thebasic topics with which an administrator should be familiar.IN THIS CHAPTER. Understanding How RPMWorks. Finding the Software. Installing Software. Updating Software. Removing Software. Verifying Software Files. Querying Package Files. Building RPM PackagesUnderstanding How RPM WorksHow does RPM work? Each software program consists offiles and directories, most of which must be located in aparticular place on the filesystem. If the software programis distributed in RPM format, these files are compressedtogether into one RPM file along with instructions onwhere the files should be located on the filesystem and anyadditional scripts or executables that must be run before orafter the files are installed. These RPM files are oftenreferred to as packages.A software program, such as the Firefox web browser, mightconsist of one RPM file. However, some programs aredivided into multiple RPM files to allow the administrator