Switch magic trackpad to pair with another mac.

trackpad-pairing-toggle.md

1. install blueutil

   brew install blueutil

2. Find your trackpad address by running

   blueutil --paired
   
   # address: 3c-a6-f6-b9-c6-c7, connected (master, 0 dBm), not favourite, paired, name: "Magic Trackpad", recent access date: 2022-05-30 2:41:17 PM +0000

   Replace - with :, you'll get 3c:a6:f6:b9:c6:c7
3. Open Automator
4. Create a new application
5. Search for Run a shell script
6. Drag to the right panel
7. Enter following script

   res=$(/opt/homebrew/bin/blueutil --is-connected 3c:a6:f6:b9:c6:c7)
   
   if [[ "$res" = '1' ]]
     then
       /opt/homebrew/bin/blueutil --unpair 3c:a6:f6:b9:c6:c7
     else
       /opt/homebrew/bin/blueutil --unpair 3c:a6:f6:b9:c6:c7
       sleep 1
       /opt/homebrew/bin/blueutil --pair 3c:a6:f6:b9:c6:c7
       sleep 1
       /opt/homebrew/bin/blueutil --connect 3c:a6:f6:b9:c6:c7
   fi

8. Save as Trackpad Pairing Toggle.app
9. Move to /Application
10. Copy this script to another device (don't forget to also install blueutil)

Now when you want to switch devices, you can use Spotlight or Alfred to search for "Trackpad Pairing Toggle" and just run the app on the connected device, it will disconnect from the current device. Then run the app on another device, it will connect to the trackpad.