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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 turn to the section called Additional Resources for more information on RPM.
Before using an RPM, you must know where to find them. An Internet search will return many RPM repositories, but if you are looking for RPM packages built by Red Hat, they can be found at the following locations:
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 typing the following command at a shell prompt:
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.
Installing packages is designed to be simple, but you may sometimes see errors:
If the package of the same version is already installed, you will see:
If you want to install the package anyway and the same version you are trying to install is already installed, you can use the --replacepkgs option, which tells RPM to ignore the error:
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.
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, you'll see:
To make RPM ignore this error, use the --replacefiles option:
RPM packages can "depend" on other packages, which means that they require other packages to be installed in order to run properly. If you try to install a package which has an unresolved dependency, you'll see:
To handle this error you should install the requested packages. If you want to force the installation anyway (a bad idea since the package probably will not run correctly), use the --nodeps option.
Uninstalling a package is just as simple as installing one. Type the following command at a shell prompt:
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:
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.
Upgrading a package is similar to installing one. Type the following command at a shell prompt:
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 will work 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:
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, you will see:
To cause RPM to "upgrade" anyway, use the --oldpackage option:
Freshening a package is similar to upgrading one. Type the following command at a shell prompt:
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 will be upgraded to the newer version. However, RPM's freshen option will not install a package if no previously-installed package of the same name exists. This differs from RPM's upgrade option, as an upgrade will 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 will do the job. If you use freshening, you will not have to deleting any unwanted packages from the group that you downloaded before using RPM.
In this case, you can simply issue the following command:
RPM will automatically upgrade only those packages that are already installed.
Use the rpm -q command to query the database of installed packages. The rpm -q foo command will print the package name, version, and release number of the installed package foo:
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.
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.
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.
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:
If everything verified properly, there will be no output. If there are any discrepancies they will be 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:
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.
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