Process is too verbose, how to stop it from flooding system.log? I'm using this application (Solar.app) from Logitech to monitor the solar cells and batteries from their own solar keyboard (K750)

One process is much too verbose and logs approx. 400 bytes in /var/log/system.log at each keystroke.

I'm looking for various solutions to prevent the process from flooding system.log.

Jan  5 17:32:11 pc96 Solar Service[702]: Input data callback for device 0x6047d0
Jan  5 17:32:11 pc96 Solar Service[702]: End of data
Jan  5 17:32:11 pc96 Solar Service[702]: Event = 1 device index = 1
Jan  5 17:32:11 pc96 Solar Service[702]: Input data callback for device 0x6047d0
Jan  5 17:32:11 pc96 Solar Service[702]: End of data
Jan  5 17:32:11 pc96 Solar Service[702]: Event = 1 device index = 1


I have been able to  find a rule to match those messages, but:

1/

# ? [= Facility com.Logitech.Solar-Service] file solar-Service.log format=raw


This rule (when used alone) actually logs the messages to a different file, in addition to system.log. Here is solar-Service.log:

[Level 4] [Time 1452071909] [TimeNanoSec 309468000] [PID 702] [Sender Solar Service] [Facility com.Logitech.Solar-Service] [CFLog Local Time 2016-01-06 10:18:29.309] [CFLog Thread 160b] [ReadUID 501] [Message Event = 1 device index = 1] [UID 501] [GID 20] [SenderMachUUID C4A60E0E-5968-829C-BC55-931BBEB0A7F7] [Host pc96]
[Level 4] [Time 1452071909] [TimeNanoSec 951289000] [PID 702] [Sender Solar Service] [Facility com.Logitech.Solar-Service] [CFLog Local Time 2016-01-06 10:18:29.951] [CFLog Thread 160b] [ReadUID 501] [Message Input data callback for device 0x6047d0] [UID 501] [GID 20] [Host pc96] [SenderMachUUID C4A60E0E-5968-829C-BC55-931BBEB0A7F7]


2/ 

? [= Facility com.Logitech.Solar-Service] ignore


.. but this rule (when used alone), does not ignore the messages.

and I don't understand why it is so.
To follow up on bmike's answer, the app identifier is com.logitech.Solar-App.  So the code you want to put in your asl.conf is

? [= Facility com.logitech.Solar-App] ignore


If you want to confirm that I'm right about your app identifier, try:

/usr/libexec/PlistBuddy -c 'Print CFBundleIdentifier' /Applications/Solar\ App.app/Contents/Info.plist 


And if you want this to go into effect right away, you can restart syslogd with something like this:

sudo launchctl unload /System/Library/LaunchDaemons/com.apple.syslogd.plist 
sudo launchctl load /System/Library/LaunchDaemons/com.apple.syslogd.plist