yum update
command is required to try to update a package or group of packages already installed. The yum update
verifies that the packages to be updated are installed, this is a difference in behavior shown by rpm -U paquete.rpm
command.
# yum update zzuf Loaded plugins:aliases, downloadonly, fastestmirror, list-data, ... Setting up Update Process Package zzuf available but not instaled. No package selected for update
# su -c "yum update xfig"