500  yum check all
  501  package-cleanup --problems
  502  package-cleanup --dupes
  503  package-cleanup --cleandupes
  504  yum-complete-transaction
  505  yum update -y
  506  yum update --skip-broken -y
  507  yum-complete-transaction --cleanup-only
  508  yum update --skip-broken -y
  509  yum check all
  510  yum clean all
  511  yum makecache
  512  rpm --rebuilddb
  513  yum update
  514  package-cleanup
  515  package-cleanup --cleandupes
  516  package-cleanup --cleandupes --skip-broken
  517  yum history
  518  yum history undo 78
  519  yum history undo 78 --skip-broken
  525  package-cleanup --cleandupes
  526  package-cleanup --cleandupes --skip-broken

--> Finished Dependency Resolution
Error: Trying to remove "systemd", which is protected
Error: Trying to remove "yum", which is protected
** Found 394 pre-existing rpmdb problem(s), 'yum check' output follows:
ModemManager-1.4.4-2.fc21.x86_64 is a duplicate with ModemManager-1.4.0-1.fc21.x86_64