Explanation
The rpm command is used to install, upgrade, query, verify and remove RPM packages on Linux systems. The
-U option is used to upgrade an existing package to a newer version, or install a package if it does not exist in the RPM database. The -U option is equivalent to -e (erase) followed by -i (install). The other options are not valid for upgrading a package. The -q option is for querying a package, the -e option is for erasing a package, the --force option is for overriding conflicts, and the -u option is not a valid option for the rpm command.
References: Using RPM Command to Install, Upgrade and Remove Packages, Linux package management with YUM and RPM