[BlueOnyx:01207] Where can I put my .sh files without them being overwritten?

[Support]

Hello,

I initially put my start.sh in /etc/rc.d/rc.local but the recent update has
recreated rc.local with the result that my code doesn't start.

I am not familiar with Linux, my code is Java so it is a Windows port, so if
you could point me to a file that will not be changed (and any steps
required to make use of that file expect for editing it) I would appreciate
it.

Tony