# rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-fedora-23-$(uname -i) # dnf upgrade # dnf clean all # dnf --releasever=23 --setopt=deltarpm=false distro-sync --nogpgcheck
# rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-fedora-22-$(uname -i) # yum update yum # yum clean all # yum --releasever=22 distro-sync
# rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-fedora-21-$(uname -i) # yum update yum # yum clean all # yum --releasever=21 distro-sync