1. Disable iMac bluetooth keyboard auto-request

Open the Bluetooth pane in System Preferences. Click the Advanced button. Uncheck the boxes marked
Open Bluetooth Setup Assistant... Disable the Bluetooth Setup Assistant.

Open System Preferences
Click Bluetooth
Click Advanced…
Uncheck Open Bluetooth Setup Assistant at startup if no keyboard is detected
Uncheck Open Bluetooth Setup Assistant at startup if no mouse or trackpad is detected
Click "OK"

2. Use Applescript to save to application

tell application "System Events" to key code 144 using command down

3. Use Applescript to add TDM application to Dock

my add_item_to_dock(choose file of type {"APPL"} with prompt "Choose an application to add to the Dock:")

on add_item_to_dock(item_path)
   try
       get item_path as alias -- you need a POSIX path so this coerces the path in case it's an HFS path, alias, file ref, etc.
       set item_path to POSIX path of item_path
   end try
   try
       tell application "Dock" to quit
   end try
   do shell script "defaults write com.apple.dock persistent-apps -array-add '<dict><key>tile-data</key><dict><key>file-data</key><dict><key>_CFURLString</key><string>" & item_path & "</string><key>_CFURLStringType</key><integer>0</integer></dict></dict></dict>'"
   try
       tell application "Dock" to activate
   end try
end add_item_to_dock

Make Mac OS icon file icns

mkdir MyIcon.iconset  
sips -z 16 16     Icon1024.png --out MyIcon.iconset/icon_16x16.png  
sips -z 32 32     Icon1024.png --out MyIcon.iconset/[email protected]  
sips -z 32 32     Icon1024.png --out MyIcon.iconset/icon_32x32.png  
sips -z 64 64     Icon1024.png --out MyIcon.iconset/[email protected]  
sips -z 128 128   Icon1024.png --out MyIcon.iconset/icon_128x128.png  
sips -z 256 256   Icon1024.png --out MyIcon.iconset/[email protected]  
sips -z 256 256   Icon1024.png --out MyIcon.iconset/icon_256x256.png  
sips -z 512 512   Icon1024.png --out MyIcon.iconset/[email protected]  
sips -z 512 512   Icon1024.png --out MyIcon.iconset/icon_512x512.png  
cp Icon1024.png MyIcon.iconset/[email protected]  
iconutil -c icns MyIcon.iconset  
rm -R MyIcon.iconset

+---------------------+--------------------+--------------+  
|      filename       | resolution, pixels | density, PPI |  
+---------------------+--------------------+--------------+  
| icon_16x16.png      | 16x16              |           72 |  
| [email protected]   | 32x32              |          144 |  
| icon_32x32.png      | 32x32              |           72 |  
| [email protected]   | 64x64              |          144 |  
| icon_128x128.png    | 128x128            |           72 |  
| [email protected] | 256x256            |          144 |  
| icon_256x256.png    | 256x256            |           72 |  
| [email protected] | 512x512            |          144 |  
| icon_512x512.png    | 512x512            |           72 |  
| [email protected] | 1024x1024          |          144 |  
+---------------------+--------------------+--------------+  

tdm-via-ssh

Target Display Mode via SSH

Slightly modified from http://aaronrutley.com/target-display-mode-via-ssh/

Installation

iMac:

1. Move all files to ~/tdm/

2. brew install blueutil

3. Set up permissions:

   • System Preferences > Sharing > Remote Login ☑
   • You will also need to give some apps accessibility access (Security & Privacy > Privacy > Accessibility). Can add it after you run the code.

MacBook:

• create alias (by pasting into ~/.bash_profile)

  • username: the user you're logging into iMac
  • hostname: the iMac's name (run hostname in iMac's terminal to get it)
  • after adding the below code, source ~/.bash_profile to take effect

  # imac target display mode function
  alias imac='function _imac(){
  	if [ $1 = "start" ]; then
  		echo "--- MacBook Bluetooth on...";
  	    blueutil -p 1;	
  		sleep 1;
  		echo "--- Connecting to iMac via ssh...";
  		ssh -2 -p 22 [email protected] sh ~/tdm/start.sh;
  	fi
  	if [ $1 = "end" ]; then
  		echo "--- MacBook Bluetooth off...";
  		blueutil -p 0;
  		sleep 1;
  		echo "--- Connecting to iMac via ssh...";
  		ssh -2 -p 22 [email protected] sh ~/tdm/end.sh;
  	fi
  	if [ $1 = "shutdown" ]; then
  		echo "--- MacBook Bluetooth off...";
  		blueutil -p 0;
  		echo "--- Shutting down remote imac.....";
  		ssh -2 -p 22 [email protected] sh ~/tdm/shutdown.sh;
  	fi
  	if [ $1 = "ssh" ]; then
  		echo "--- Connecting via ssh.....";
  		ssh [email protected];
  	fi
  };_imac'

• SSH into iMac without password:

  • Snippet from: https://danielpataki.com/target-display-mode-remotely/ (archived)

  # when you issue the following command you'll be asked some questions, keep hitting enter until done.
  ssh-keygen
  scp ~/.ssh/id_rsa.pub [email protected]:~/
  ssh [email protected]
  mkdir .ssh # skip this if you already have the folder
  cat id_rsa.pub >> ~/.ssh/authorized_keys
  rm -f id_rsa.pub
  exit

Usage

imac start: start TDM

imac end: end TDM

imac shutdown

imac ssh: ssh into iMac

https://medium.com/@gutofoletto/how-to-share-your-imac-keyboard-on-target-display-mode-abfaf10a7992

#!/usr/bin/env bash
# Disable BT on remote machine and enable it on local machine, so KB/Mouse reconnect to local machine.  
#ensure local bluetooth is off  
blueutil off  
#disable imac bluetooth  
ssh [email protected] '/usr/local/bin/blueutil off'  
#enable local bluetooth  
blueutil on  

#!/usr/bin/env bash  
# Disable BT on local machine and enable it on remote machine, so KB/Mouse reconnect to remote machine.  
#ensure local bluetooth is off  
blueutil off  
#enable imac bluetooth  
ssh [email protected] '/usr/local/bin/blueutil on'