MacOS – Python stopped working after Mountain Lion upgrade

Not at all - I have three classes of macs that all worked flawlessly with the upgrade to Lion. They all share their screens with the basic VNC technology:

• basic OS X - turn on VNC or remote management - bonjour location is local
• basic plus MobileMe back to my mac for locating the mac over the internet
• basic plus Screens app from edovia to locate the mac over the internet

I haven't seen a good Apple writeup of the Lion changes - but when you log in with your OS account rather than with the VNC password - you get a distinct loginwindow process for that account whether or not that user is shown as logged in locally. This change could be causing you grief.

Put another way - screen sharing and log in is now a virtual concept - you are no longer limited to one mac log in session or tied tightly to the physical screen. User A can be using the mac and User B logs in remotely and gets their own workspace rather than seeing what A is doing or forcing A to log off.

The writeup inside the screens app is nice if you have purchased it.

For anyone who ends up on this page, I realized I should post the answer:

Using launchd instead of cron does indeed fix the authorization problem. Your user launchd jobs (which run only when you are logged in) correctly use the SSH agent information that was unlocked via your keychain as part of login (as part of standard OS X key management, no other software required).

To minimize my interactions with launchd, I created a single launchd job that calls a bash script. In this way I can simply edit the script without dealing with launchd.

Here's the launchd file:

<?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>com.mycron.hourly</string>

  <key>ProgramArguments</key>
  <array>
    <string>/Users/john/bin/cron.hourly</string>
  </array>

  <key>Nice</key>
  <integer>1</integer>

  <key>StartInterval</key>
  <integer>3600</integer> <!-- start every X seconds -->

  <key>RunAtLoad</key>
  <true/>
</dict>
</plist>

I saved the file to ~/Library/LaunchAgents/com.mycron.hourly.plist, and then loaded it with:

launchctl load ~/Library/LaunchAgents/com.mycron.hourly.plist

Once loaded, it will run right away and then again every 60 minutes.

If you follow the same procedure, you'll want to change the `ProgramArguments' string with the right path to your script.