MacOS – Auto run a UI app and click a button on startup

You could try inspecting the output of

$ pkgutil --pkgs

to see if any of the names look like the package that claims to be installed, then

$ pkgutil --pkg-info thatpackage

to see where it was installed. If it's not actually found there, you could try

$ sudo pkgutil --forget thatpackage

and see if the App Store will let you re-download; but at that point I'd probably contact App Store support first, as mucking with the package database might cause bigger problems (like, conceivably, forgetting that you ever bought the program — although I would hope Apple's programmers were smarter than that).

Logout hooks were deprecated in 10.4, but they still work as of 10.9.

sudo defaults write com.apple.loginwindow LogoutHook ~/.logouthook
echo $'#!/bin/bash\nsay a' > ~/.logouthook
chmod +x ~/.logouthook

The value of the LogoutHook key can only be a path to an executable and not a shell command. The logout hook is run as root.

The defaults command modifies /var/root/Library/Preferences/com.apple.loginwindow.plist. Adding a LogoutHook key to /Library/Preferences/com.apple.loginwindow.plist doesn't work.

If a logout hook takes long enough to run, a gray screen is shown until the logout hook terminates. There doesn't seem to be any time limit after which logout hooks are forced to terminate.

I haven't figured out any way to run programs on logout reliably with launchd. When I tried trapping signals like EXIT, the code in the trap was only run when I logged out to the login window and not when I shut down or restarted.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
  <key>Label</key>
  <string>test</string>
  <key>ProgramArguments</key>
  <array>
    <string>bash</string>
    <string>-c</string>
    <string>trap 'echo a>/Users/username/Desktop/a;say a' EXIT;while :;do sleep 10;done</string>
  </array>
  <key>RunAtLoad</key>
  <true/>
</dict>
</plist>