Enable Fast User Switching on macOS 10.12

Enable Fast User Switching.sh

#!/bin/bash

# (C) Andrew Worth Carson
# MIT License: https://andrewworthcarson.com/mit_license.html

for user in $(dscl . list /Users UniqueID | awk '$2 >= 500 {print $1}'); do
    userHome=$(dscl . read /Users/"$user" NFSHomeDirectory | sed 's/NFSHomeDirectory://' | grep "/" | sed 's/^[ \t]*//')
    if [ "$(defaults read "${userHome}/Library/Preferences/com.apple.systemuiserver.plist" 2> /dev/null | grep -i user.menu)" == "" ]; then
        touch "${userHome}/Library/Preferences/com.apple.systemuiserver.plist"
        defaults write "${userHome}/Library/Preferences/com.apple.systemuiserver.plist" menuExtras -array-add '<string>/System/Library/CoreServices/Menu Extras/User.menu</string>'
    fi
done
defaults write /Library/Preferences/.GlobalPreferences MultipleSessionEnabled -bool Yes
killall -HUP SystemUIServer

Updated user iteration.

I tried this snippet in my script at https://gist.github.com/ChristopherA/98628f8cd00c94f11ee6035d53b0d3c6

However, on execution in Monterey I get:

Could not write domain /Library/Preferences/.GlobalPreferences

My terminal already has full disk access permissions (tested near the top of my script.)

Any suggestions?

I've also tried sudo, which gets rid of the above error, however, the fast user switching icon does not show up after killall -HUP SystemUIServer.

@ChristopherA thanks for the info. I revisited this script briefly today and it seems like the .GlobalPreferences.plist no longer manages these settings on Monterey. I'm not sure when that changed as I haven't used this script in quite a while.

I'll need to do some digging in my off-time to figure out how they're managed. I'll update this script if I figure it out.