Run a script only at shutdown (not log off or restart) on Mac OS X

Question

Is there any way to run a script only at shutdown?

I mean, only when the computer is really shutting down to off state. This script should not run when doing just a log off or restart.

Answer 1

Few days ago I published on github a configuration/script able to be executed at boot/shutdown.

Basically on Mac OS X you could/should use a System wide and per-user daemon/agent configuration file (plist) in conjunction with a bash script file. This is a sample of the plist file you could use:

<?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>boot.shutdown.script.name</string>

<key>ProgramArguments</key>
<array>
  <string>SCRIPT_PATH/boot-shutdown.sh</string>
</array>

<key>RunAtLoad</key>
<true/>

<key>StandardOutPath</key>
<string>LOG_PATH/boot-shutdown.log</string>

<key>StandardErrorPath</key>
<string>LOG_PATH/boot-shutdown.err</string>

</dict>
</plist>

You can place this file into /Library/LaunchDaemons. There are many directories where the plist file could be placed, it depends from what you need, the rights of the process and so on.

~/Library/LaunchAgents         Per-user agents provided by the user.
/Library/LaunchAgents          Per-user agents provided by the administrator.
/Library/LaunchDaemons         System wide daemons provided by the administrator.
/System/Library/LaunchAgents   Mac OS X Per-user agents.
/System/Library/LaunchDaemons  Mac OS X System wide daemons.

This script boot-shutdown.sh will be loaded and executed at every boot/shutdown.

#!/bin/bash
function shutdown()
{

  # INSERT HERE THE COMMAND YOU WANT EXECUTE AT SHUTDOWN OR SERVICE UNLOAD

  exit 0
}

function startup()
{

  # INSERT HERE THE COMMAND YOU WANT EXECUTE AT STARTUP OR SERVICE LOAD

  tail -f /dev/null &
  wait $!
}

trap shutdown SIGTERM
trap shutdown SIGKILL

startup;

Then call launchctl command which load and unload daemons/agents.

sudo launchctl load -w /Library/LaunchDaemons/boot-shutdown-script.plist