Dependencies and available compilers

These are our requirements (in particular we highlight those that are not usually installed by default) - previous versions may or may not work:

You will also require a Linux kernel with support for control groups and namespaces. Support has been in the Linux kernel since 2.6.32. Other distributions, or systems with custom kernels, may not have support enabled. At a minimum, you will need to enable the following Linux kernel options: CONFIG_CGROUPS, CONFIG_CGROUP_CPUACCT, CONFIG_MEMCG (previously called as CONFIG_CGROUP_MEM_RES_CTLR), CONFIG_CPUSETS, CONFIG_PID_NS, CONFIG_IPC_NS, CONFIG_NET_NS. It is anyway suggested to use Linux kernel version at least 3.8.

Then you require the compilation and execution environments for the languages you will use in your contest:

  • GNU compiler collection (for C, C++ and Java, respectively with executables gcc, g++ and gcj);
  • alternatively, for Java, your choice of a JDK, for example OpenJDK (but any other JDK behaving similarly is fine, for example Oracle’s);
  • Free Pascal (for Pascal, with executable fpc);
  • Python >= 2.7 (for Python, with executable python2 or python3; in addition you will need zip);
  • PHP >= 5 (for PHP, with executable php);
  • Glasgow Haskell Compiler (for Haskell, with executable ghc);
  • Rust (for Rust, with executable rustc);
  • C# (for C#, with executable mcs).

All dependencies can be installed automatically on most Linux distributions.


On Ubuntu 18.04, one will need to run the following script to satisfy all dependencies:

# Feel free to change OpenJDK packages with your preferred JDK.
sudo apt-get install build-essential openjdk-8-jdk-headless fp-compiler \
    postgresql postgresql-client python3.6 cppreference-doc-en-html \
    cgroup-lite libcap-dev zip

# Only if you are going to use pip/venv to install python dependencies
sudo apt-get install python3.6-dev libpq-dev libcups2-dev libyaml-dev \
    libffi-dev python3-pip

# Optional
sudo apt-get install nginx-full python2.7 php7.2-cli php7.2-fpm \
    phppgadmin texlive-latex-base a2ps gcj-jdk haskell-platform rustc \

The above commands provide a very essential Pascal environment. Consider installing the following packages for additional units: fp-units-base, fp-units-fcl, fp-units-misc, fp-units-math and fp-units-rtl.

Arch Linux

On Arch Linux, unofficial AUR packages can be found: cms or cms-git. However, if you do not want to use them, the following command will install almost all dependencies (some of them can be found in the AUR):

sudo pacman -S base-devel jdk8-openjdk fpc postgresql postgresql-client \
    python libcap

# Install the following from AUR.

# Only if you are going to use pip/venv to install python dependencies
sudo pacman -S --needed postgresql-libs libcups libyaml python-pip

# Optional
sudo pacman -S --needed nginx python2 php php-fpm phppgadmin texlive-core \
    a2ps ghc rust mono

Preparation steps

Download CMS 1.4.rc1 from GitHub as an archive, then extract it on your filesystem. You should then access the cms folder using a terminal.


If you decided to git clone the repository instead of downloading the archive, and you didn’t use the --recursive option when cloning, then you need to issue the following command to fetch the source code of the sandbox:

git submodule update --init

In order to run CMS there are some preparation steps to run (like installing the sandbox, compiling localization files, creating the cmsuser, and so on). You can either do all these steps by hand or you can run the following command:

sudo python3 install

This script will add you to the cmsuser group if you answer Y when asked. If you want to handle your groups by yourself, answer N and then run:

sudo usermod -a -G cmsuser <your user>

You can verify to be in the group by issuing the command:


Remember to logout, to make the change effective.


Users in the group cmsuser will be able to launch the isolate program with root permission. They may exploit this to gain root privileges. It is then imperative that no untrusted user is allowed in the group cmsuser.

Installing CMS and its Python dependencies

There are a number of ways to install CMS and its Python dependencies:

Method 1: Global installation with pip

There are good reasons to install CMS and its Python dependencies via pip (Python Package Index) instead of your package manager (e.g. apt-get). For example: two different Linux distro (or two different versions of the same distro) may offer two different versions of python-sqlalchemy. When using pip, you can choose to install a specific version of sqlalchemy that is known to work correctly with CMS.

Assuming you have pip installed, you can do this:

sudo pip3 install -r requirements.txt
sudo python3 install

This command installs python dependencies globally. Note that on some distros, like Arch Linux, this might interfere with the system package manager. If you want to perform the installation in your home folder instead, then you can do this instead:

pip3 install --user -r requirements.txt
python3 install --user

Method 2: Virtual environment

An alternative method to perform the installation is with a virtual environment, which is an isolated Python environment that you can put wherever you like and that can be activated/deactivated at will.

You will need to create a virtual environment somewhere in your filesystem. For example, let’s assume that you decided to create it under your home directory (as ~/cms_venv):

python3 -m venv ~/cms_venv

To activate it:

source ~/cms_venv/bin/activate

After the activation, the pip command will always be available (even if it was not available globally, e.g. because you did not install it). In general, every python command (python, pip) will refer to their corresponding virtual version. So, you can install python dependencies by issuing:

pip3 install -r requirements.txt
python3 install


Once you finished using CMS, you can deactivate the virtual environment by issuing:


Method 3: Using apt-get on Ubuntu


It is usually possible to install python dependencies using your Linux distribution’s package manager. However, keep in mind that the version of each package is controlled by the package mantainers and could be too new or too old for CMS. On Ubuntu, this is generally not the case since we try to build on the python packages that are available for the current LTS version.

To install CMS and its Python dependencies on Ubuntu, you can issue:

sudo python3 install

sudo apt-get install python3-setuptools python3-tornado python3-psycopg2 \
     python3-sqlalchemy python3-psutil python3-netifaces python3-crypto \
     python3-six python3-bs4 python3-coverage python3-mock python3-requests \
     python3-werkzeug python3-gevent python3-bcrypt python3-chardet patool \
     python3-babel python3-xdg python3-future python3-jinja2

# Optional.
# sudo apt-get install python3-yaml python3-sphinx python3-cups python3-pypdf2

Method 4: Using pacman on Arch Linux


It is usually possible to install python dependencies using your Linux distribution’s package manager. However, keep in mind that the version of each package is controlled by the package mantainers and could be too new or too old for CMS. This is especially true for Arch Linux, which is a bleeding edge distribution.

To install CMS python dependencies on Arch Linux (again: assuming you did not use the aforementioned AUR packages), you can issue:

sudo python3 install

sudo pacman -S --needed python-setuptools python-tornado python-psycopg2 \
     python-sqlalchemy python-psutil python-netifaces python-crypto \
     python-six python-beautifulsoup4 python-coverage python-mock \
     python-requests python-werkzeug python-gevent python-bcrypt \
     python-chardet python-babel python-xdg python-future python-jinja

# Install the following from AUR.

# Optional.
# sudo pacman -S --needed python-yaml python-sphinx python-pycups
# Optionally install the following from AUR.

Configuring the worker machines

Worker machines need to be carefully set up in order to ensure that evaluation results are valid and consistent. Just running the evaluations under isolate does not achieve this: for example, if the machine has an active swap partition, memory limit will not be honored.

Apart from validity, there are many possible tweaks to reduce the variability in resource usage of an evaluation.

We suggest following isolate’s guidelines for reproducible results.

Running CMS non-installed

To run CMS without installing it in the system, you need first to build the prerequisites:

python3 build

There are still a few steps to complete manually in this case. First, add CMS and isolate to the path and create the configuration files:

export PATH=$PATH:./isolate/
export PYTHONPATH=./
cp config/cms.conf.sample config/cms.conf
cp config/cms.ranking.conf.sample config/cms.ranking.conf

Second, perform these tasks (that require root permissions):

  • create the cmsuser user and a group with the same name;
  • add your user to the cmsuser group;
  • set isolate to be owned by root:cmsuser, and set its suid bit.

For example:

sudo useradd cmsuser
sudo usermod -a -G cmsuser <your user>
sudo chown root:cmsuser ./isolate/isolate
sudo chmod u+s ./isolate/isolate

Updating CMS

As CMS develops, the database schema it uses to represent its data may be updated and new versions may introduce changes that are incompatible with older versions.

To preserve the data stored on the database you need to dump it on the filesystem using cmsDumpExporter before you update CMS (i.e. with the old version).

You can then update CMS and reset the database schema by running:


To load the previous data back into the database you can use cmsDumpImporter: it will adapt the data model automatically on-the-fly (you can use cmsDumpUpdater to store the updated version back on disk and speed up future imports).