Android O: identify battery sucking apps

Source: Android O: How to Identify and Bitch Slap Those Battery Sucking Apps
On my Oneplus 5T, Android 8.1:

List apps. running in background permanently

• Settings > Dev. Options > Running Services 

Kill the background activity of an app.

• Settings > Apps > Application list > Select app > Battery > Uncheck Background activity

macOS mojave: bluetooth headphones keep on disconnecting

Uncheck "Allow Handoff between this Mac and your iCloud devices" in Preferences | General.

macOS: xcrun: error: invalid active developer path

Source: macOS Mojave: invalid active developer path
If after upgrading from High Sierra to Mojave, you get the following error:

[jerome@jeroboam] > make
xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools),
missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun

Then re-install xcode developer tools like in:

[jerome@jeroboam] > xcode-select --install
xcode-select: note: install requested for command line developer tools