In Debian derived distributions, you can use the official Crystal repository.
First you have to add the repository to your APT configuration. For easy setup just run in your command line:
curl https://dist.crystal-lang.org/apt/setup.sh | sudo bash
That will add the signing key and the repository configuration. If you prefer to do it manually, execute the following commands as root:
apt-key adv --keyserver keys.gnupg.net --recv-keys 09617FD37CC06B54 echo "deb https://dist.crystal-lang.org/apt crystal main" > /etc/apt/sources.list.d/crystal.list apt-get update
Once the repository is configured you're ready to install Crystal:
sudo apt-get install crystal
When a new Crystal version is released you can upgrade your system using:
sudo apt-get update sudo apt-get install crystal
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https://crystal-lang.org/docs/installation/on_debian_and_ubuntu.html