gkrellm software package provides GNU Krell Monitors, 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 gkrellm
gkrellm is installed in your system.
Make ensure the gkrellm package were installed using the commands given below,
$ sudo dpkg-query -l | grep gkrellm *
You will get with gkrellm package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | X Window System software |
| Package | gkrellm |
| Version | 2.3.8-1 |
| Description | GNU Krell Monitors |
| Sub Section | x11 |