This page provides answers to some commonly asked questions. Feel free to use the GitLab issues if you cannot find an answer here.

I just enrolled in the course, what should I do?

Welcome! Take a look around the website, especially the links in the side bar which lead to additional pages with information about lectures and labs (along with links to resources).

These are the essential points for getting started:

  • Most information in this course is disseminated through Git repositories in MFF GitLab. It is therefore imperative that you have a working account. You should be able to log in using your SIS user identifier and password — the account will be automatically created on your first login.

  • Visit the course project group and open your repository. The repository name consists of a student- prefix followed by your SIS identifier. The repository title page contains links to information about course organization (the rules document), self study instructions for each lecture, graded quizzes, and assignment specifications.

  • Read the rules document.

  • Keep in mind that self study is a mandatory prerequisite to lecture participation and the lecture will not substitute for self study. Similarly, labs are meant for discussion about assignments and we assume that you will have read the assignment specifications.

  • Check for quizzes and assignments that you can still submit within the deadline, and start working on them as soon as possible.

If you have any questions, please post an issue in the forum GitLab project.

GitLab: where is it and how do I sign in?

When we refer to GitLab in this course, we always mean the faculty instance available at https://gitlab.mff.cuni.cz.

Use your CAS credentials to log in, i.e., the same credentials you use to access SIS. Use the username derived from your first and family name (such as doejohn) instead of the numerical identifier.

Your first login will activate your GitLab account. Without that, it is impossible to provide you with access to project repositories required for participation in this course and you will not be able to submit the assignments and quizzes required to pass this course.

Troubleshooting

If you cannot log in, try changing your CAS password (even to a temporary one — you can change it back to your original password later) to trigger password synchronization. Note that you may need to wait up to one full day before the effect of the synchronization becomes visible.

For some new accounts (typically Erasmus students and, in certain situations, also BIOINF students) it is necessary to wait for an extra synchronization round that is performed at midnight every day. Try to change the password the next morning and try logging in to GitLab few hours after that.

Note also that you need to have an account with so-called verified password (this typically applies to Erasmus students). You need to visit one of these offices to verify your account.

Also note that for some accounts, projects were enabled only after you filled-in your e-mail address in your profile.

If nothing helps, contact us as soon as possible at teachers-nswi004@d3s.mff.cuni.cz.

Logging to the lab machine

Connect to port 22004 (standard SSH port + course code) of the machine lab.d3s.mff.cuni.cz using your SIS credentials.

Consider adding the following fragment to your ~/.ssh/config to simplify the login to bare ssh nswi004.

Host nswi004
    HostName lab.d3s.mff.cuni.cz
    User YOUR_SIS_LOGIN
    Port 22004

Note that this machine contains all that is needed to compile and run the assignments.

Logging to GNU/Linux machines in Rotunda lab

You will need a Secure Shell (SSH) client. On GNU/Linux machines, the SSH client is typically part of a base installation, so you should be able to simply run the ssh command. Windows 10 (21H2 and possibly earlier versions) provide an OpenSSH client as an optional component. If the OpenSSH client is not available, you will need to install an external SSH client. We recommend using PuTTY, but feel free to use any other client.

Connect to u-plN.ms.mff.cuni.cz (where N is a number between 1 and 23) using your SIS credentials (i.e. the same username and password).

Note that machines in Rotunda use AFS and Kerberos and thus it is not possible to setup a login via a public SSH key.

Generally, you should prefer the lab machine (see above) as it contains the latest versions of the toolchain. And it supports authentication via public key too.

Keeping your fork up-to-date

Most of the (later) assignments and the self-study material will be published in form of changes committed to the respective upstream repository. You are expected to merge these updates into your private repositories. When you view your private repository in GitLab, the corresponding upstream repository will be shown as the repository you Forked from.

For example, when we add a new quiz, we will commit the changes to the upstream repository and announce the update via e-mail.

To merge these changes into your student-LOGIN repository for the first time, you need to perform the following steps (for subsequent updates, you will only need to perform the last 3 steps):

  1. Clone your private repository and/or change to the directory with the clone.

    git clone git@gitlab.mff.cuni.cz:teaching/nswi004/2022/student-LOGIN.git

    cd student-LOGIN

    You need to be inside the clone directory for the subsequent steps.

  2. Add a remote pointing to the upstream repository.

    git remote add upstream git@gitlab.mff.cuni.cz:teaching/nswi004/2022/upstream/student.git

    This only needs to be done once per clone.

  3. Fetch changes from the upstream repository.

    git fetch upstream

  4. Merge the changes.

    git merge -m "Merge upstream changes" upstream/master

    Git will respond with an "Already up to date." message and do nothing if there is nothing to merge.

  5. Push the merged changes from your (local) clone back to your private repository on faculty GitLab.

    git push

A more detailed explanation is also available in the labs for Introduction to Linux course (NSWI177).

Merging partial changes from upstream

Sometimes it may happen that we will publish minor updates to the assignment (e.g. when we find a bug in the tests). And thus sometimes you may need to merge only certain upstream changes.

To merge only certain commits (note that it is possible to select any commit via cherry-picking, the following focuses on the simpler case when we want to merge up to some commit) following commands will do the trick.

Assuming we are inside team-whatever directory:

  1. Ensure we have upstream up-to-date.

    git remote add upstream git@gitlab.mff.cuni.cz:teaching/nswi004/2022/upstream/team.git
git fetch upstream

  2. Merge changes up to a certain commit first (the commit mentioned relates to updates to A02).

    git checkout master
git merge ee551427e853808e04f6bf611500025bd390fb06 -m "Merge upstream changes"

  3. Optionally, we may create a new branch where we would merge rest of upstream changes (here, because A03 breaks all tests as they are not even launched).

    git branch a03-import
git checkout a03-import
git merge upstream/master -m "Merge A03"

Introductory materials

The materials from the Computer Systems (NSWI170) course can help in refreshing your knowledge of the C language and basic principles of program execution.

The materials from the Introduction to Linux (NSWI177) course can help in refreshing your knowledge in the following areas: