The preferred way to run on-shot commands after boot when using Archlinux + initscripts, is placing them in the rc.local file. Also, initscripts provide a handy helper which creates a service file that runs these commands on boot when using systemd. If you want to completely move away from initscripts, to a pure systemd-based system, you need to create service file(s) for these commands.

The following is an example service file that adjust the HDD spindown levels.

Description=Fix excessive HDD parking frequency

ExecStart=/sbin/hdparm -B 220 /dev/sda


The most notable options here are the oneshot service type and the RemainAfterExit option. The oneshot service type is used to indicate that the command should exit before starting any follow-up units. We also set the RemainAfterExit option to true to indicate that this service should be considered active after it exits. Finally, keep in mind that you need the full command path in ExecStart.