adb software package provides Android Debug Bridge, 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 adb
adb is installed in your system.
Make ensure the adb package were installed using the commands given below,
$ sudo dpkg-query -l | grep adb *
You will get with adb package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Development |
| Package | adb |
| Version | 1:6.0.1+r55-1 |
| Description | Android Debug Bridge |
| Sub Section | devel |