caffeinate

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Control system power states (sleeping, preventing sleep, screen locking, etc)
NOTE: Any sleep preventions will be removed when hs.reload() is called. A future version of the module will save/restore state across reloads.
Submodules
​hs.caffeinate.watcher​
API Overview
Functions - API calls offered directly by the extension
​currentAssertions​
​declareUserActivity​
​fastUserSwitch​
​get​
​lockScreen​
​logOut​
​restartSystem​
​sessionProperties​
​set​
​shutdownSystem​
​startScreensaver​
​systemSleep​
​toggle​
API Documentation
Functions
​currentAssertions​
Signature
hs.caffeinate.currentAssertions()
Type
Function
Description
Fetches information about processes which are currently asserting display/power sleep restrictions
Parameters
None
Returns
A table containing information about current power assertions, with process IDs (PID) as the keys, each of which may contain multiple assertions
​declareUserActivity​
Signature
hs.caffeinate.declareUserActivity([id])
Type
Function
Description
Informs the OS that the user performed some activity
Parameters
id - An option number containing the assertion ID returned by a previous call of this function
Returns
A number containing the ID of the assertion generated by this function
Notes
This is intended to simulate user activity, for example to prevent displays from sleeping, or to wake them up
It is not mandatory to re-use assertion IDs if you are calling this function mulitple times, but it is recommended that you do so if the calls are related
​fastUserSwitch​
Signature
hs.caffeinate.fastUserSwitch()
Type
Function
Description
Show the Fast User Switch screen (ie a login screen without logging out first)
Parameters
None
Returns
None
​get​
Signature
hs.caffeinate.get(sleepType) -> bool or nil
Type
Function
Description
Queries whether a particular sleep type is being prevented
Parameters
sleepType - A string containing the type of sleep to inspect (see hs.caffeinate.set() for information about the possible values)
Returns
True if the specified type of sleep is being prevented, false if not. nil if sleepType was an invalid value
​lockScreen​
Signature
hs.caffeinate.lockScreen()
Type
Function
Description
Locks the displays
Parameters
None
Returns
None
Notes
This function uses private Apple APIs and could therefore stop working in any given release of macOS without warning.
​logOut​
Signature
hs.caffeinate.logOut()
Type
Function
Description
Request the system log out the current user
Parameters
None
Returns
None
​restartSystem​
Signature
hs.caffeinate.restartSystem()
Type
Function
Description
Request the system reboot
Parameters
None
Returns
None
​sessionProperties​
Signature
hs.caffeinate.sessionProperties()
Type
Function
Description
Fetches information from the display server about the current session
Parameters
None
Returns
A table containing information about the current session, or nil if an error occurred
Notes
The keys in this dictionary will vary based on the current state of the system (e.g. local vs VNC login, screen locked vs unlocked).
​set​
Signature
hs.caffeinate.set(sleepType, aValue, acAndBattery)
Type
Function
Description
Configures the sleep prevention settings
Parameters
sleepType - A string containing the type of sleep to be configured. The value should be one of:
displayIdle - Controls whether the screen will be allowed to sleep (and also the system) if the user is idle.
systemIdle - Controls whether the system will be allowed to sleep if the user is idle (display may still sleep).
system - Controls whether the system will be allowed to sleep for any reason.
aValue - A boolean, true if the specified type of sleep should be prevented, false if it should be allowed
acAndBattery - A boolean, true if the sleep prevention should apply to both AC power and battery power, false if it should only apply to AC power.
Returns
None
Notes
These calls are not guaranteed to prevent the system sleep behaviours described above. The OS may override them if it feels it must (e.g. if your CPU temperature becomes dangerously high).
The acAndBattery argument only applies to the system sleep type.
You can toggle the acAndBattery state by calling hs.caffeinate.set() again and altering the acAndBattery value.
The acAndBattery option does not appear to work anymore - it is based on private API that is not allowed in macOS 10.15 when running with the Hardened Runtime (which Hammerspoon now uses).
​shutdownSystem​
Signature
hs.caffeinate.shutdownSystem()
Type
Function
Description
Request the system log out and power down
Parameters
None
Returns
None
​startScreensaver​
Signature
hs.caffeinate.startScreensaver()
Type
Function
Description
Request the system start the screensaver (which may lock the screen if the OS is configured to do so)
Parameters
None
Returns
None
​systemSleep​
Signature
hs.caffeinate.systemSleep()
Type
Function
Description
Requests the system to sleep immediately
Parameters
None
Returns
None
​toggle​
Signature
hs.caffeinate.toggle(sleepType) -> bool or nil
Type
Function
Description
Toggles the current state of the specified type of sleep
Parameters
sleepType - A string containing the type of sleep to toggle (see hs.caffeinate.set() for information about the possible values)
Returns
True if the specified type of sleep is being prevented, false if not. nil if sleepType was an invalid value
Notes
If systemIdle is toggled to on, it will apply to AC only