a2jmidid software package provides Daemon for exposing legacy ALSA MIDI in JACK MIDI systems, 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 a2jmidid
a2jmidid is installed in your system.
Make ensure the a2jmidid package were installed using the commands given below,
$ sudo dpkg-query -l | grep a2jmidid *
You will get with a2jmidid package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Sound |
| Package | a2jmidid |
| Version | 8~dfsg0-2 |
| Description | Daemon for exposing legacy ALSA MIDI in JACK MIDI systems |
| Sub Section | Sound |