I was hoping to use it to allow my first cgminer-dmaxl to start in rc.local, which will pick up all my Gridseed minis in SHA256 mode, then have the Minera cgminer-dmaxl instance start say 1 minute later in scrypt mode.
It seems if I set a delay in settings, both my rc.local entry AND the minera instance get delayed exactly the same. So i then have to kill the scrypt instance (sometimes via the api instead of the minera menu as it wont always work, seems to be 50/50) once Scrypt is stopped, the SHA will generally pick up all the gridseeds over the next minute (hotplug for the win) and then i can start the scrypt instance again (works fine from the dashboard).
Note: the rc.local entry is via the minera dashboard option, as putting it directly into etc/rc.local gets overwritten on reboot ( i presume by minera dashboard)
rc.local is always overwritten by Minera, but you have the textarea on settings page to add your personal lines.
the delay option does only one simple thing: it changes the sleep time in the rc.local file, by default it's 5 seconds.
[...]
sleep 5
su - minera -c "/usr/bin/screen -dmS cpuminer /var/www/minera/minera-bin/minerd --retries=1 -c /var/www/minera/conf/miner_conf.json"
[...]
If you have more then one miner starting from rc.local you should add sleep before each one.