B.2.2. Installing and Upgrading

RPM packages typically have file names like tree-1.5.3-2.el6.x86_64.rpm. The file name includes the package name (tree), version (1.5.3), release (2), operating system major version (el6) and CPU architecture (x86_64).
You can use rpm's -U option to:
  • upgrade an existing but older package on the system to a newer version, or
  • install the package even if an older version is not already installed.
That is, rpm -U <rpm_file> is able to perform the function of either upgrading or installing as is appropriate for the package.
Assuming the tree-1.5.3-2.el6.x86_64.rpm package is in the current directory, log in as root and type the following command at a shell prompt to either upgrade or install the tree package as determined by rpm: 
rpm -Uvh tree-1.5.3-2.el6.x86_64.rpm

Note

The -v and -h options (which are combined with -U) cause rpm to print more verbose output and display a progress meter using hash signs.
If the upgrade/installation is successful, the following output is displayed: 
Preparing...                ########################################### [100%]
   1:tree                   ########################################### [100%]

Warning

rpm provides two different options for installing packages: the aforementioned -U option (which historically stands for upgrade), and the -i option, historically standing for install. Because the -U option subsumes both install and upgrade functions, we recommend to use rpm -Uvh with all packages except kernel packages.
You should always use the -i option to install a new kernel package instead of upgrading it. This is because using the -U option to upgrade a kernel package removes the previous (older) kernel package, which could render the system unable to boot if there is a problem with the new kernel. Therefore, use the rpm -i <kernel_package> command to install a new kernel without replacing any older kernel packages. For more information on installing kernel packages, see Chapter 30, Manually Upgrading the Kernel.
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: tree-1.5.3-2.el6.x86_64.rpm: Header V3 RSA/SHA256 signature: BAD, key ID
d22e77f2
If it is a new, header-only, signature, an error message such as the following is displayed: 
error: tree-1.5.3-2.el6.x86_64.rpm: Header V3 RSA/SHA256 signature: BAD,
key ID d22e77f2
If you do not have the appropriate key installed to verify the signature, the message contains the word NOKEY: 
warning: tree-1.5.3-2.el6.x86_64.rpm: Header V3 RSA/SHA1 signature: NOKEY, key ID 57bbccba
See Section B.3, “Checking a Package's Signature” for more information on checking a package's signature.

B.2.2.1. Package Already Installed

If a package of the same name and version is already installed, the following output is displayed: 
Preparing...                ########################################### [100%]
  package tree-1.5.3-2.el6.x86_64 is already installed
However, if you want to install the package anyway, you can use the --replacepkgs option, which tells RPM to ignore the error: 
rpm -Uvh --replacepkgs tree-1.5.3-2.el6.x86_64.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.