Like most things in the GUI, the Power Management system has a tool in the CLI, pmset, that will give you access to the various power settings. This would be useful for headless “servers” like a Mac Mini media center or old G4 hidden away in a closet or the like.
The items in the below chart can be controlled with the pmset utility. Call pmset with -c to change the settings when on a charger (wall power), -b for battery power, -u for UPS power, or -a for all.
| Name |
Function |
Unit |
Default |
| dim |
Time until display dims |
minutes |
5 |
| spindown |
Time until the disk spins down |
minutes |
5 |
| sleep |
Time until sleep |
minutes |
15 |
| womp |
Enable Wake on Ethernet Magic Packet (WOMP) |
boolean |
Yes |
| ring |
Enable wake on ring |
boolean |
No |
| autorestart |
Automatically restart after power failure |
boolean |
No |
| dps |
Cycle up CPU on high load |
boolean |
Yes |
| reduce |
Variable CPU speed |
boolean |
No |
| powerbutton |
Sleep on power button |
boolean |
Yes |
| lidwake |
Toggle system wake when the lid is opened (closed clamshell mode) |
boolean |
Yes |
| acwake |
Toggle system wake when power mode is changed (on/off battery) |
boolean |
No |
As of 10.3.3 pmset also controls the system’s response to USB UPS devices. The following controls are available:
| Name |
Function |
Unit |
Default |
| haltlevel |
When draining UPS battery power, the percent capacity to trigger a system halt |
percent |
off |
| haltafter |
When draining UPS battery power, the amount of time allowed to elapse before system halt |
minutes |
off |
| haltremain |
When draining UPS battery power, trigger a system halt when this much time is left on the battery |
minutes |
off |
If you want to know the current settings, run pmset -g with one of: live for current settings, disk for settings on-disk, ups for the current UPS settings, sched for the scheduled startup/shutdown configuration, or cap for power management capabilities (listed as the commands in the above charts).
