Here are some notes for setting up an autorun script on my QNAP TS-231:

Connect via ssh and issue the following commands to mount the partition where the configuration resides:

ubiattach -m  6  -d  2 
/ bin / mount  -t ubifs ubi2:config / tmp / config

Edit the autorun.sh file:

vi  / tmp / config / autorun.sh

Assign execute permissions and unmount the configuration partition:

chmod + x /tmp/config/autorun.sh umount / tmp / config​​​​
 
ubidetach -m  6

Enable autorun.sh to start automatically from the web interface by going to “Control Panel / System / Hardware / General” and enable the “Run user-defined processes during startup” checkbox:

Source: https://wiki.qnap.com/wiki/Running_Your_Own_Application_at_Startup