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7.2. Using RPM

RPM has five basic modes of operation (not counting package building): installing, uninstalling, upgrading, querying, and verifying. This section contains an overview of each mode. For complete details and options, try rpm --help or refer to Section 7.5 Additional Resources for more information on RPM.

7.2.1. Finding RPM Packages

Before using an RPM, you must know where to find them. An Internet search returns many RPM repositories, but if you are looking for RPM packages built by Red Hat, they can be found at the following locations:

7.2.2. Installing

RPM packages typically have file names like foo-1.0-1.i386.rpm. The file name includes the package name (foo), version (1.0), release (1), and architecture (i386). To install a package, log in as root and type the following command at a shell prompt:

rpm -Uvh foo-1.0-1.i386.rpm

If installation is successful, the following output is displayed:

Preparing...                ########################################### [100%]
   1:foo                    ########################################### [100%]

As you can see, RPM prints out the name of the package and then prints a succession of hash marks as the package is installed as a progress meter.

The signature of a package is checked automatically when installing or upgrading a package. The signature confirms that the package was signed by an authorized party. For example, if the verification of the signature fails, an error message such as the following is displayed:

error: V3 DSA signature: BAD, key ID 0352860f

If it is a new, header-only, signature, an error message such as the following is displayed:

error: Header V3 DSA signature: BAD, key ID 0352860f

If you do not have the appropriate key installed to verify the signature, the message contains the word NOKEY such as:

warning: V3 DSA signature: NOKEY, key ID 0352860f

Refer to Section 7.3 Checking a Package's Signature for more information on checking a package's signature.

WarningWarning
 

If you are installing a kernel package, you should use rpm -ivh instead. Refer to Chapter 29 Manually Upgrading the Kernel for details.

Installing packages is designed to be simple, but you may sometimes see errors.

7.2.2.1. Package Already Installed

If the package of the same version is already installed, the following is displayed:

Preparing...                ########################################### [100%]
package foo-1.0-1 is already installed

If the same version you are trying to install is already installed, and you ewant to install the package anyway, you can use the --replacepkgs option, which tells RPM to ignore the error:

rpm -ivh --replacepkgs foo-1.0-1.i386.rpm

This option is helpful if files installed from the RPM were deleted or if you want the original configuration files from the RPM to be installed.

7.2.2.2. Conflicting Files

If you attempt to install a package that contains a file which has already been installed by another package or an earlier version of the same package, the following is displayed:

Preparing...                ########################################### [100%]
file /usr/bin/foo from install of foo-1.0-1 conflicts with file from package bar-2.0.20

To make RPM ignore this error, use the --replacefiles option:

rpm -ivh --replacefiles foo-1.0-1.i386.rpm

7.2.2.3. Unresolved Dependency

RPM packages can, essentially, depend on other packages, which means that they require other packages to be installed to run properly. If you try to install a package which has an unresolved dependency, output similar to the following is displayed:

error: Failed dependencies:
        bar.so.2 is needed by foo-1.0-1
    Suggested resolutions:
        bar-2.0.20-3.i386.rpm

If you are installing a package from the Red Hat Enterprise Linux CD-ROM set, it usually suggest the package(s) needed to resolve the dependency. Find the suggested package(s) on the Red Hat Enterprise Linux CD-ROMs or from the Red Hat FTP site (or mirror), and add it to the command:

rpm -ivh foo-1.0-1.i386.rpm bar-2.0.20-3.i386.rpm

If installation of both packages is successful, output similar to the following is displayed:

Preparing...                ########################################### [100%]
   1:foo                    ########################################### [ 50%]
   2:bar                    ########################################### [100%]

If it does not suggest a package to resolve the dependency, you can try the --redhatprovides option to determine which package contains the required file. You need the rpmdb-redhat package installed to use this option.

rpm -q --redhatprovides bar.so.2

If the package that contains bar.so.2 is in the installed database from the rpmdb-redhat package, the name of the package is displayed:

bar-2.0.20-3.i386.rpm

To force the installation anyway (which is not recommended since the package may not run correctly), use the --nodeps option.

7.2.3. Uninstalling

Uninstalling a package is just as simple as installing one. Type the following command at a shell prompt:

rpm -e foo

NoteNote
 

Notice that we used the package name foo, not the name of the original package file foo-1.0-1.i386.rpm. To uninstall a package, replace foo with the actual package name of the original package.

You can encounter a dependency error when uninstalling a package if another installed package depends on the one you are trying to remove. For example:

error: Failed dependencies:
        foo is needed by (installed) bar-2.0.20-3.i386.rpm

To cause RPM to ignore this error and uninstall the package anyway, which may break the package depending on it, use the --nodeps option.

7.2.4. Upgrading

Upgrading a package is similar to installing one. Type the following command at a shell prompt:

rpm -Uvh foo-2.0-1.i386.rpm

As part of upgrading a package, RPM automatically uninstalls any old versions of the foo package. In fact, you may want to always use -U to install packages which works even when there are no previous versions of the package installed.

TipTip
 

You don't want to use the -U option for installing kernel packages because RPM replaces the previous kernel package. This does not affect a running system, but if the new kernel is unable to boot during your next restart, there would be no other kernel to boot instead.

Using the -i option adds the kernel to your GRUB boot menu (/etc/grub.conf). Similarly, removing an old, unneeded kernel removes the kernel from GRUB.

Because RPM performs intelligent upgrading of packages with configuration files, you may see a message like the following:

saving /etc/foo.conf as /etc/foo.conf.rpmsave

This message means that your changes to the configuration file may not be forward compatible with the new configuration file in the package, so RPM saved your original file and installed a new one. You should investigate the differences between the two configuration files and resolve them as soon as possible, to ensure that your system continues to function properly.

Upgrading is really a combination of uninstalling and installing, so during an RPM upgrade you can encounter uninstalling and installing errors, plus one more. If RPM thinks you are trying to upgrade to a package with an older version number, the output is similar to the following:

package foo-2.0-1 (which is newer than foo-1.0-1) is already installed

To force RPM to upgrade anyway, use the --oldpackage option:

rpm -Uvh --oldpackage foo-1.0-1.i386.rpm

7.2.5. Freshening

Freshening a package is similar to upgrading one. Type the following command at a shell prompt:

rpm -Fvh foo-1.2-1.i386.rpm

RPM's freshen option checks the versions of the packages specified on the command line against the versions of packages that have already been installed on your system. When a newer version of an already-installed package is processed by RPM's freshen option, it is upgraded to the newer version. However, RPM's freshen option does not install a package if no previously-installed package of the same name exists. This differs from RPM's upgrade option, as an upgrade does install packages, whether or not an older version of the package was already installed.

RPM's freshen option works for single packages or package groups. If you have just downloaded a large number of different packages, and you only want to upgrade those packages that are already installed on your system, freshening does the job. If you use freshening, you do not have to delete any unwanted packages from the group that you downloaded before using RPM.

In this case, issue the following command:

rpm -Fvh *.rpm

RPM automatically upgrades only those packages that are already installed.

7.2.6. Querying

Use the rpm -q command to query the database of installed packages. The rpm -q foo command displays the package name, version, and release number of the installed package foo:

foo-2.0-1

NoteNote
 

To query a package, replace foo with the actual package name.

Instead of specifying the package name, use the following options with -q to specify the package(s) you want to query. These are called Package Selection Options.

There are a number of ways to specify what information to display about queried packages. The following options are used to select the type of information for which you are searching. These are called Information Query Options.

For the options that display lists of files, add -v to the command to display the lists in a familiar ls -l format.

7.2.7. Verifying

Verifying a package compares information about files installed from a package with the same information from the original package. Among other things, verifying compares the size, MD5 sum, permissions, type, owner, and group of each file.

The command rpm -V verifies a package. You can use any of the Package Verify Options listed for querying to specify the packages you wish to verify. A simple use of verifying is rpm -V foo, which verifies that all the files in the foo package are as they were when they were originally installed. For example:

If everything verified properly, there is no output. If there are any discrepancies, they are displayed. The format of the output is a string of eight characters (a c denotes a configuration file) and then the file name. Each of the eight characters denotes the result of a comparison of one attribute of the file to the value of that attribute recorded in the RPM database. A single period (.) means the test passed. The following characters denote failure of certain tests:

If you see any output, use your best judgment to determine if you should remove or reinstall the package, or fix the problem in another way.