Chapter 5

Getting Information
About Packages

Table 5.1. Query-mode command syntax and options.

5.1. rpm -q: What Does It Do?

One of the nice things about using RPM is that the packages you manage don't end up going into some kind of black hole. Nothing would be worse than to install, upgrade, and erase several different packages and not have a clue as to what's on your system. In fact, RPM's query function can help you get out of sticky situations such as the following:

• You're poking around your system and you come across a file that you just can't identify. Where did it come from?
• Your friend sends you a package file and you have no idea what the package does, what it installs, or where it originally came from.
• You know that you installed XFree86 a couple months ago, but you don't know what version and you can't find any documentation on it.

The list could go on, but you get the idea. The rpm -q command is what you need. If you're the kind of person who doesn't like to have more options than you know what to do with, rpm -q might look imposing. But fear not. Once you have a handle on the basic structure of an RPM query, it'll be a piece of cake.

5.2. The Parts of an RPM Query

It becomes easy to construct a query command when you understand the individual parts. First is the -q (you can also use --query, if you like). After all, you need to tell RPM what function to perform, right? The rest of a query command consists of two distinct parts: package selection (or what packages you'd like to query) and information selection (or what information you'd like to see). Let's take a look at package selection first.

5.2.1. Query Commands, Part I: Package Selection

The first thing you'll need to decide when issuing an RPM query is what package (or packages) you'd like to query. RPM has several ways to specify packages, so you have quite an assortment to choose from.

Earlier chapters discuss RPM's package label, a string that uniquely identifies every installed package. Every label contains three pieces of information:

• The name of the packaged software
• The version of the packaged software
• The package's release number

When issuing a query command using package labels, you must always include the package name. You can also include the version and even the release, if you like. The only restrictions are that each part of the package label specified must be complete and that if any parts of the package label are missing, all parts to the right must be omitted as well. This second restriction is just a long way of saying that if you specify the release, you must specify the version as well. Let's look at a few examples.

Say, for instance, you've recently installed a new version of the C libraries, but you can't remember the version number:

# rpm -q libc

libc-5.2.18-1

#

In this type of query, RPM returns the complete package label for all installed packages that match the given information. In this example, if version 5.2.17 of the C libraries were also installed, its package label would have been displayed, too.

In this example, we've included the version as well as the package name:

# rpm -q rpm-2.3

rpm-2.3-1

#

Note, however, that RPM is a bit picky about specifying package names. Here are some queries for the C library that won't work:

# rpm -q LibC

package LibC is not installed

#



# rpm -q lib

package lib is not installed

#



# rpm -q "lib*"

package lib* is not installed

#



# rpm -q libc-5

package libc-5 is not installed

#



# rpm -q libc-5.2.1

package libc-5.2.1 is not installed

#

As you can see, RPM is case sensitive about package names and cannot match partial names, version numbers, or release numbers. Nor can it use the wildcard characters we've come to know and love. As we've seen, however, RPM can perform the query when more than one field of the package label is present. In this case, rpm -q libc-5.2.18, or even rpm -q libc-5.2.18-1 would have found the package, libc-5.2.18-1.