i3blocks software package provides highly flexible status line for the i3 window manager, 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 i3blocks
i3blocks is installed in your system.
Make ensure the i3blocks package were installed using the commands given below,
$ sudo dpkg-query -l | grep i3blocks *
You will get with i3blocks package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | X Window System software |
| Package | i3blocks |
| Version | 1.4-3 |
| Description | highly flexible status line for the i3 window manager |
| Sub Section | x11 |