apertium-cat software package provides Apertium single language data for Catalan, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install apertium-cat
apertium-cat is installed in your system.
Make ensure the apertium-cat package were installed using the commands given below,
$ sudo dpkg-query -l | grep apertium-cat *
You will get with apertium-cat package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Science |
| Package | apertium-cat |
| Version | 1.0.0~r65787-1 |
| Description | Apertium single language data for Catalan |
| Sub Section | Science |