flightcrew software package provides C++ epub validator, 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 flightcrew
flightcrew is installed in your system.
Make ensure the flightcrew package were installed using the commands given below,
$ sudo dpkg-query -l | grep flightcrew *
You will get with flightcrew package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Text Processing |
| Package | flightcrew |
| Version | 0.7.2+dfsg-7+b1 |
| Description | C++ epub validator |
| Sub Section | Text |