16.2. Using RPM

16.2.1. 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:

• The Red Hat Enterprise Linux CD-ROMs

• The Red Hat Errata Page available at http://www.redhat.com/apps/support/errata/

• A Red Hat FTP Mirror Site available at http://www.redhat.com/download/mirror.html

• Red Hat Network — Refer to Chapter 18 Red Hat Network for more details on Red Hat Network

16.2.2. 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). Installing a package is as simple as logging in as root and typing 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.

Starting with version 4.1 of RPM, the signature of a package is checked automatically when installing or upgrading a package. If verifying 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 16.3 Checking a Package's Signature for more information on checking a package's signature.

	Note
	If you are installing a kernel package, you should use rpm -ivh instead. Refer to Chapter 39 Upgrading the Kernel for details.

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

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

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

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

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

Preparing...                ########################################### [100%]
error: Failed dependencies:
        bar.so.2 is needed by foo-1.0-1
    Suggested resolutions:
        bar-2.0.20-3.i386.rpm

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

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

rpm -q --redhatprovides bar.so.2

bar-2.0.20-3.i386.rpm

16.2.3. Uninstalling

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

rpm -e foo

	Note
	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:

Preparing...                ########################################### [100%]
error: removing these packages would break dependencies:
        foo is needed by  bar-2.0.20-3.i386.rpm

To cause RPM to ignore this error and uninstall the package anyway (which is also a bad idea since the package that depends on it will probably fail to work properly), use the --nodeps option.

16.2.4. 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

What you do not see above is that RPM automatically uninstalled any old versions of the foo package. In fact, you may want to always use -U to install packages, since it works even when there are no previous versions of the package installed.

Since 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 cause RPM to "upgrade" anyway, use the --oldpackage option:

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

16.2.5. 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 a group of packages. 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.

16.2.6. 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

	Note
	Notice that we used the package name foo. To query a package, you need to replace foo with the actual package name.

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

• -a queries all currently installed packages.

• -f <file> queries the package which owns <file>. When specifying a file, you must specify the full path of the file (for example, /usr/bin/ls).

• -p <packagefile> queries the package <packagefile>.

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 Selection Options.

• -i displays package information including name, description, release, size, build date, install date, vendor, and other miscellaneous information.

• -l displays the list of files that the package contains.

• -s displays the state of all the files in the package.

• -d displays a list of files marked as documentation (man pages, info pages, READMEs, etc.).

• -c displays a list of files marked as configuration files. These are the files you change after installation to adapt the package to your system (for example, sendmail.cf, passwd, inittab, etc.).

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

16.2.7. 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 Selection 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:

• To verify a package containing a particular file:

  rpm -Vf /bin/vi

• To verify ALL installed packages:

  rpm -Va

• To verify an installed package against an RPM package file:

  rpm -Vp foo-1.0-1.i386.rpm

  This command can be useful if you suspect that your RPM databases are corrupt.

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 . (a period) means the test passed. The following characters denote failure of certain tests:

• 5 — MD5 checksum

• S — file size

• L — symbolic link

• T — file modification time

• D — device

• U — user

• G — group

• M — mode (includes permissions and file type)

• ? — unreadable file

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.