nandorocker / alfred-tdm-workflow

Target Display Mode is not made easy by Apple. I'm trying to do it myself.

Target Display Mode script

How it works (currently)

iMac

I made a shell script ~/bin/tdm.ssh:

osascript -e 'tell application "System Events" to key code 144 using command down'

It invokes an AppleScript which presses CMD+F2. I also added laptop's RSA to the authorized_keys list.

Laptop

I connect to the iMac (hardwired address) and run that shell script:

ssh -t [e-mail] "sh ~/bin/tdm.sh"

Goals

• To recognize and locate the iMac dynamically ("Mac connected via Thunderbolt")
• To execute the command directly, without the shell script on the iMac
• To wake the iMac remotely

Finding the IP

With this command, you can find the IP of whatever's connected as bridge0:

arp -a | grep "bridge0" | grep -oE "(\d{1,3}\.){3}\d{1,3}" | uniq

However, there are two issues with this approach:

• It doesn't uniquely identify the device connected to the laptop, as bridge0 repeats. You should instead somehow locate the device with the laptop's Thunderbolt's MAC address, and then locate whatever device is connected to it (assuming you only have one device connected)
• Most importantly, the laptop doesn't immediately connect to the iMac when you plug in the Thunderbolt.
  If you connect to it even once, now it shows up on arp -a but not before that. So either there's a way to make the Mac automatically connect, or there has to be another way to locate the machine.