These instructions are for attendees of the 2025 CMS Data Analysis School at the Fermilab LHC Physcis Center. Others can follow the instructions specific to Fermilab site and computing access, but the chats and support sections will not be active outside the school.

Mattermost (chat)

There is a dedicated Mattermost team, called CMSDAS@LPC 2025, created to facilitate communication and discussions via live chat (which is also archived). Please join the team now! This is how most of the real-time communication will take place during the school.

If you have never used Mattermost at CERN, start by clicking on the links above, and login with CERN SSO (single sign-on). The link above should auto-join you to the CMSDAS “Team”; you can also find it by searching (click “+” in your list of teams; not channels, mind!).

If you already have used Mattermost at CERN, please know that when you click direct links to channels (as you will find below) that are within the CMSDAS@LPC 2025 team, you may be redirected to the last Mattermost team you used. If this happens, remember to click the signup link to join the CMSDAS@LPC 2025 team) to switch to the correct team from which you should be able to see the individual channels. If that still doesn’t work, remove all cookies associated with cern.ch and restart your browser.

The PreExercisesChannel will be available once you join or switch to the CMSDAS@LPC 2025 team!

Note that you can access Mattermost via browser or you can download the corresponding application running standalone on your laptop or smartphone. The laptop application does not work with CERN certificate login.

Support email

For CMSDAS@LPC 2025, you may e-mail cmsdasatlpc@fnal.gov with a detailed description of your problem. The instructors will be happy to help you.

Obtain a Computer Account

To get a CERN account, please have a look at Get Account at CERN. Obtaining a CERN account can be time-consuming and requires response from people at CERN during CERN business hours. CERN is closed for the winter holiday (Dec. 21, 2024 - Jan. 5, 2025). CERN account application starts with the institutional team leader filling out a pre-registration form, so your institutional team leader also needs to be available for this task.

Site specific instructions

• LPC/Fermilab - this can take some time (up to 4-6 weeks!) and also requires people to be available to approve accounts, start the request early!
  • Configure your laptop to connect to the cmslpc-el8.fnal.gov LPC UAF cluster at Fermilab
  • Windows Kerberos at FNAL

Here are some additional links in case you are using Windows:

• Hints for setting up Cygwin - preferred
• How to install and configure PuTTy

Warning

If you are attending CMSDAS at the LPC, you should do the pre-exercises on the cmslpc-el8.fnal.gov cluster using the computer you intend to use at CMSDAS.

Obtain a Grid Certificate and CMS VO Registration

A Grid Certificate and CMS VO registration will be needed for the next set of exercises. The registration process can be time-consuming (actions by several people are required), so it is important to start it as soon as possible. There are two main requirements which can be simply summarized: A certificate ensures that you are who you claim to be. A registration in the VO recognizes you (identified by your certificate) as a member of CMS. Use the following link for this: Fermilab guide to getting CMS CERN grid certificate and CMS VO. Both are needed to submit jobs to the grid and access files remotely using XRootD. Make sure you follow any additional instructions for US-CMS users.

Obtain a GitHub Account

Most CMS software is hosted on GitHub. GitHub is a Git repository web-based hosting service, while git is a distributed version control system. In your future analysis work, version control of your analysis code will become a very important task and git will be very useful.

In order to checkout and develop CMS software, you will need a github account, which is free.

• In case you don’t have one already, simply go to https://github.com/join and follow the instructions to create a new account. Choose your username wisely, ideally based on your actual name, as it will be used to sign all of your contributions to CMS code!
• In case you already have an account you can simply use the “Sign in” dialog and put your username and password.
• Make sure you register an SSH key in GitHub, following these instruction. Remember, when you generate an SSH key, two files are generated; the public key (ending in .pub) is uploaded to github.com, while the private key (not ending in .pub) is put on cmslpc at ~/.ssh/. Make sure the permissions of your private key are set using chmod 600 ~/.ssh/id_rsa. You can register more than one SSH key and it’s usually a good idea to do so for every computer/cluster on which you regularly work (i.e. your laptop, cmslpc, your university cluster, etc.). You don’t need to use an ssh-agent, but you can try if you want to. For more about ssh-agents, see CMSGitTutorial#SSH_agent_in_logon_file.
• You may also find it useful to launch ssh-agent at login time. Instructions are at CMSGitTutorialPublic#bash .

Windows specific setup

If you would like to use cygwin, you will need to install winpty and prefix your docker command like winpty docker. Windows Subsystem for Linux can also be used; once installed (whichever flavor of Linux you prefer), you can largely follow the Unix instructions.