docker-transmission-openvpn/docs/custom-scripts.md

If you ever need to run custom code before or after transmission is executed or stopped, you can use the custom scripts feature. Custom scripts are located in the /scripts directory which is empty by default. To enable this feature, you'll need to mount the /scripts directory.

Once /scripts is mounted you'll need to write your custom code in the following bash shell scripts:

Script	Function
/scripts/openvpn-pre-start.sh	This shell script will be executed before openvpn start
/scripts/transmission-pre-start.sh	This shell script will be executed before transmission start
/scripts/transmission-post-start.sh	This shell script will be executed after transmission start
/scripts/transmission-pre-stop.sh	This shell script will be executed before transmission stop
/scripts/transmission-post-stop.sh	This shell script will be executed after transmission stop

Don't forget to include the #!/bin/bash shebang and to make the scripts executable using chmod a+x