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Lock/logoff/disable Apple Mac if network cable unplugged

Posted on 2010-11-08
Last Modified: 2012-06-27
Can anyone think of a way to lock/logoff/disable an iMac when the network cable is unplugged or it loses network connectivity?

Our students unplug the network cable in an effort to stop remote control and avoid managed preferences.

Running OSX Snow Leopard

Any help/ideas appreciated!

Question by:Elthamtech
  • 3
  • 3
LVL 17

Expert Comment

ID: 34091688

The above link shows you how to launch a process when network status changes.  You can then launch a script to do what you want using launchctl when the network status goes to down - and likewise restore everything when they plug it in again.

Author Comment

ID: 34098505
I am fairly new to the Mac world...Do you think you could please explain to me how that works?
LVL 17

Accepted Solution

sweetfa2 earned 500 total points
ID: 34185921
The script in question does a lot of things, you won't need to do much of them.

You need to add the plist changes to your LaunchAgents directory.
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN"
<plist version="1.0">

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You need to create a script (which the plist actually refers to - referring to a script you create).  The one in the example is overly complex for what you want.

The script just needs to lock the computer.

There is the script below taken from http://hintsforums.macworld.com/archive/index.php/t-30274.html

# This script uses Panther's "Fast User Switching"
# to switch to the user whose username is specified as a command-line arg.
# If no arg is specified, it brings up the login window.
# Based on a script on the MacOSXHints site:
# http://www.macosxhints.com/article.php?story=20031102031045417

MENUEXTRAS="/System/Library/CoreServices/Menu Extras"

if [[ -z $1 ]]; then
"$CGSESSION" -suspend
USERID=`id -u $1`;
if [[ -z $USERID ]]; then
exit -1;

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Author Comment

ID: 34201827
The second script says there's a syntax error somewhere on this line:

if [[ -z $1 ]]; then

Expected “,” or “]” but found unknown token.
LVL 17

Expert Comment

ID: 36469680
if [[ -z "$1" ]]; then

Author Comment

ID: 36470637
All good - cheers I sorted that out. Took a while to get back to it,  but when I did your posts helped!

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