Category Archives: Uncategorized

Printing at CERN

Using an operating system other than those officially supported, printers can be added via CUPS.

Example from Fedora 34:

Find your printer from cern’s printservice webpage. Copy the printer ppd from lxplus and install deps:

sudo dnf install -y cups-lpd system-config-printer
scp lxplus:/etc/cups/ppd/your-printer-name.ppd ~

From here, run system-config-printer and configure a new LPD/LPR printer.

Host: <your-printer-name>

Queue: <your-print-name>

then simply accept the rest of the default settings & test print!

Enabling h264 and others on Windows N insider

Windows 10 N is essentially the same version as the non-N version, with specific licensed codecs and other materials excluded. You can install these normally via the Microsoft Windows Media Feature Packs.

I made the unfortunate mistake of selecting Windows 10 Pro N for a computer, and being stubborn and not wanting to change the license, I have been continuously running into problems created when you update early with Windows Insider program.

So far, Microsoft does not rebuild the media feature packs for insider builds. Microsoft has not released a script to let you do this yourself (ala source rebuild for those familiar with Linux).

If you want to use Netflix, youtube, or any other modern web content that requires these media codecs, you were SOL on Windows 10 N and insider builds.

Until I stumbled across these instructions:

  1. Download the latest Windows Media Feature Pack & extract the contents:
    • expand -f:* Windows-media-packxx.msu . ; expand -f:* .
  2. Copy the following files into Windows/System32:
  • mfperfhelper.dll
  • msmpeg2vdec.dll
  • mf.dll
  • mfplat.dll
  • evr.dll
  1. Install the following registry keys: (copy/paste to .reg file and import by double-clicking the file)
  2. Windows Registry Editor Version 5.00
    @="Microsoft H264 Video Decoder MFT"
    @="MF Media Source Activate"

Using Fedora 24+ at CERN

Updated Spring 2018

It seems RHEL8/CC7 will likely be branched from Fedora27 development, so hopefully these things will hold for future. Tracking down the sssd bug for Fedora 26+ was a pain!

CERN has decided that future linux releases will be a stock version of centos + cern repository. This makes things quite simple for anyone who might want to use fedora, as we are very close to stock system.

add CERN repo
cat>/etc/yum.repo.d/cern.repo << EOF [cern] name=cern baseurl= enabled=1 gpgcheck=0 EOF
Install kerberos and afs
Install gotcha dependencies

ocsinventory-agent -this package is not any longer from default Fedora repos. Get it here.

# for Fedora 27. See above link for other versions of Fedora
dnf install
Install packages from cern repo
  • dnf may complain about per(Module::Install) or other perl libraries missing – these are simply called perl-Module-Install in fedora repos. is your friend here.
sudo dnf install CERN-CA-certs cern-get-keytab cern-get-sso-cookie cern-wrappers locmap useraddcern

Now we install everything with dnf. Finally, you can simply follow the cern cc7 instructions and add your cern account native with addusercern afsid

One final note: If you have Fedora 26+, there is a bug from sssd. You need to add the following line to your /etc/sssd/sssd.conf under [sssd]:


You can read more about this particular “feature” here

Building KDE (Plasma) 5 on RHEL / CentOS 7

With a fresh install of CentOS 7 I’m going to try and install KDE (Plasma) 5.

For fun, I’ll try and make it available to all users from the /opt/ directory.

According to KDE Developers the reason why Plasma is not available from repositories is due to missing support for cmake 2.8.12+.

UPDATED – CMAKE 3.5+ is now available in the epel-testing repo! QT5.6 is now available as well!

SO! Step1: Install dependencies:

yum-config-manager --enable epel-testing
yum install cmake3*, qt5-* 
ln -s /usr/bin/cmake3 /usr/bin/cmake

*cmake for centos7 does not install as `cmake’ but cmake3. I do not know why.

Test with “qtdiag” (should return 5.5.1) and “cmake3 -version”(should return 3.5.0)


To build latest* we need wayland. New(er) Wayland. Without building yourself from source, you can get it from jmliger’s copr. Once you have that saved in /etc/yum.repos.d/ you can simply

yum install wayland*


Step 2: Build KDE*

I chose to use the KDE src-build script to make life easier.

Note: my kdesrc-builrc file was in /opt/kde/sources/kdesrc-build/ and the contents are as follows:


    source-dir  /opt/kde/sources
    build-dir  /opt/kde/build
    kdedir  /opt/kde/install
    log-dir  /opt/kde/logs

    git-repository-base     kde-projects kde:
    cmake-options -DCMAKE_BUILD_TYPE:STRING=debug

    cxxflags -pipe -DQT_STRICT_ITERATORS -DQURL_NO_CAST_FROM_STRING -DQT_NO_HTTP -DQT_NO_FTP -Wformat -Werror=format-security -Werror=return-type -Wno-variadic-macros -Wlogical-op -Wmissing-include-dirs -std=c++11

    make-options -j4

    ignore-kde-structure    true       
    stop-on-failure         true       

end global

include /opt/kde/sources/kdesrc-build/kf5-frameworks-build-include
include /opt/kde/sources/kdesrc-build/kf5-workspace-build-include

In addition to the above official instructions, I needed bzr, and some other additional *-devel libraries (build with –debug flag to see what you’re missing)

Working KDE/Plasma 5.21 on Centos 7.2