12-30-2019
They mean: copying a file, especially a big file, is done in steps. If there is a power loss in between, the status of the file is unknown: can be empty or partially copied.
In contrast, renaming/moving a file is "atomic": after a power loss it's either 100% the new file or 100% the old file.
But with a copy speed of >100 Mbyte per second and "journaling" it is a bit paranoid to assume a power loss within these microseconds, IMHO.
So that's why I prefer to keep the inode intact (including attributes and link count), and simply assume that power will last for the next microseconds.
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LEARN ABOUT OPENDARWIN
pmset
PMSET(1) BSD General Commands Manual PMSET(1)
NAME
pmset -- modify power management settings
SYNOPSIS
pmset [-a | -b | -c] [dim minutes] [spindown minutes] [sleep minutes] [womp 1/0] [ring 1/0] [autorestart 1/0] [dps 1/0] [reduce 1/0]
[powerbutton 1/0] [lidwake 1/0] [acwake 1/0] [boot]
pmset -g [disk | live | cap | sched]
DESCRIPTION
pmset changes and reads power management settings such as idle sleep timing, wake on administrative access, automatic restart on power loss,
etc.
SETTING
The -a, -b, -c flags determine whether the settings apply to battery (-b), charger (wall power) (-c), or all (-a).
Use a minutes argument of 0 to set the idle time to never.
pmset must be run as root.
The boot argument tells power management that system bootup is complete. Loginwindow handles this on a normal Mac OS X system.
GETTING
The -g flag outputs the settings currently in use (same as -g live ). -g disk will tell you the settings on disk. -g cap will tell you
which power management features the machine supports. -g sched will show scheduled startup/wake and shutdown/sleep events.
ARGUMENTS
dim - display dim timer (value in minutes)
spindown - disk spindown timer (value in minutes)
sleep - system sleep timer (value in minutes)
womp - wake on ethernet magic packet (value = 0/1)
ring - wake on modem ring (value = 0/1)
autorestart - automatic restart on power loss (value = 0/1)
dps - dynamically change processor speed based on load (value = 0/1)
reduce - reduce processor speed (value = 0/1)
powerbutton - sleep the machine when power button is pressed (value = 0/1)
lidwake - wake the machine when the laptop lid(or clamshell) is opened (value = 0/1)
acwake - wake the machine when power source (AC/battery) is changed (value = 0/1)
OTHER ARGUMENTS
These arguments don't directly affect power management settings:
boot - tell the kernel that system boot is complete
EXAMPLES
pmset -b dim 5
pmset -a dim 10 spindown 10 sleep 30 womp 1
pmset -g live
FILES
All changes made through pmset are saved in a persistent preferences file (per-system, not per-user) at
/Library/Preferences/SystemConfiguration/com.apple.PowerManagement.plist
pmset modifies the same file that System Preferences Energy Saver modifies.
Darwin August 19, 2002 Darwin