Package management w/ dnf is fast

Yum feels slow sometimes. That's not new. I was impressed by zif and how much quicker it is. And now, once again I'm impressed how quick dnf is.
Besides beeing quick - dnf is also looking quite clean.
So let's see when it get's into a prominent position, for now you can install it on Fedora 18 by using

$ sudo yum install -y dnf

The commandset is not yet as comprehensive as yums, but the basics are working.

Migrate your fav. packages to a new workstation.

Once in a while we are setting up our workstations - yet again.
I often faced the problem to migrate my finest selection of packages from my former system, to the new one.
Groups are surely one way to install roughly those packages you need on the new system, but in very rare cases your package selection is unique.

The following snippet might help you, to install the packages of DA_OLD_HOST on your new system.
On your new host:

$ ssh $DA_OLD_HOST 'rpm -qa --qf "%{NAME}\n"' \
  | xargs yum install -y --skip-broken

Hint: It seems as if something is broken with the fedora mirros, you can work around problems by commenting the mirrorlist and uncommenting the baseurl option in the appropriate yum repo .conf.

Package management using zif.

As yum was introduced I was happy about it's features. Also some of the later features like history and the rollback are nice and handy.
But yum can be slow.

If you want to use a different rpm high-level management system with a comparable featureset to yum give zif a try:

$ sudo yum install -y zif-tools PackageKit-zif

This also installs the zif backend for PackageKit - which appears to the user as the package update dialog.
Many known commands will work:

$ zif search yum
$ sudo zif install -y livecd-tools
$ zif # will print help

yum update fails in Fedora 16 because of broken certificates

Today (and also the last days) I ran into trouble when updating my system.
yum update ran silently in to the error:

$ sudo yum update -y
Geladene Plugins: auto-update-debuginfo, langpacks, presto, refresh-packagekit
Fehler: Cannot retrieve repository metadata (repomd.xml) for repository:
fedora. Please verify its path and try again

That didn't tell me a lot about the error, also a yum clean metadata didn't help.
After a bit of googling I stumbled across the URLGRABBER_DEBUG variable which tells yum to debug all URL fetching stuff, this lead me to the error:

$ sudo URLGRABBER_DEBUG=1 yum update -y
Geladene Plugins: auto-update-debuginfo, langpacks, presto, refresh-packagekit
...
Could not get metalink https://mirrors.fedoraproject.org/metalink?
repo=fedora-debug-16&arch=x86_64 error was
14: Peer cert cannot be verified or peer cert invalid
Fehler: Cannot retrieve repository metadata (repomd.xml) for repository: 
fedora. Please verify its path and try again

It was discovered last year that such errors are not passed to the user, but it might be a good idea to fix this.
To get around the error you can temporarily disable the verification of hosts using yum's setopt switch:

$ sudo yum update --setopt=sslverify=false