esptool software package provides create and flash firmware files to ESP8266 or ESP32 chips, 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 esptool
esptool is installed in your system.
Make ensure the esptool package were installed using the commands given below,
$ sudo dpkg-query -l | grep esptool *
You will get with esptool package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Electronics |
| Package | esptool |
| Version | 0.4.6-1 |
| Description | create and flash firmware files to ESP8266 or ESP32 chips |
| Sub Section | Electronics |