Automatically disable Wifi when an Ethernet connection (cable) is plugged in on a Mac

com.mine.toggleairport.plist

<?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.asb.toggleairport</string>
  <key>OnDemand</key>
  <true/>
  <key>ProgramArguments</key>
  <array>
    <string>/Library/Scripts/toggleAirport.sh</string>
  </array>
  <key>WatchPaths</key>
  <array>
    <string>/Library/Preferences/SystemConfiguration</string>
  </array>
</dict>
</plist>

Installation.md

Overview

This is a bash script that will automatically turn your wifi off if you connect your computer to an ethernet connection and turn wifi back on when you unplug your ethernet cable/adapter. If you decide to turn wifi on for whatever reason, it will remember that choice. This was improvised from this mac hint to work with Yosemite, and without hard-coding the adapter names. My particular fork: 1- comments out notifications completely as I've found it to be pretty buggy, and I don't really care if users are notified or not & 2- adds functionality to handle external USB Ethernet devices (work in progress). Feel free to fork and fix any issues you encounter.

Most the credit for these changes go to Dave Holland.

Requirements

• Mac OSX 10+
• Administrator privileges

Installation Instructions

• Copy toggleAirport.sh to /Library/Scripts/
• Run chmod 755 /Library/Scripts/toggleAirport.sh
• Copy com.mine.toggleairport.plist to /Library/LaunchAgents/
• Run chmod 644 /Library/LaunchAgents/com.mine.toggleairport.plist
• Run sudo launchctl load /Library/LaunchAgents/com.mine.toggleairport.plist to start the watcher

Uninstall Instructions

• Run sudo launchctl unload /Library/LaunchAgents/com.mine.toggleairport.plist to stop the watcher
• Delete /Library/Scripts/toggleAirport.sh
• Delete /Library/LaunchAgents/com.mine.toggleairport.plist
• Delete /private/var/tmp/prev_eth_on
• Delete /private/var/tmp/prev_air_on

Misc

To debug, just run: sudo /Library/Scripts/toggleAirport.sh and add echo's wherever you'd like

toggleAirport.sh

#!/bin/bash

function set_airport {

    new_status=$1

    if [ $new_status = "On" ]; then
        /usr/sbin/networksetup -setairportpower $air_name on
        touch /var/tmp/prev_air_on
    else
        /usr/sbin/networksetup -setairportpower $air_name off
        if [ -f "/var/tmp/prev_air_on" ]; then
            rm /var/tmp/prev_air_on
        fi
    fi

}

#function growl {

    # Checks whether Growl is installed
    #if [ -f "/usr/local/bin/growlnotify" ]; then
    #    /usr/local/bin/growlnotify -m "$1" -a "AirPort Utility.app"
    #else
    #    osascript -e "display notification \"$1\" with title \"Wifi Toggle\" sound name \"Hero\""
    #fi

#}

# Set default values
prev_eth_status="Off"
prev_air_status="Off"
eth_status="Off"

# Grab the names of the adapters. We assume here that any ethernet connection name ends in "Ethernet"
eth_names=`networksetup -listnetworkserviceorder | sed -En 's/^\(Hardware Port: (.*LAN|.*Ethernet), Device: (en.)\)$/\2/p'`
air_name=`networksetup -listnetworkserviceorder | sed -En 's/^\(Hardware Port: (Wi-Fi|AirPort), Device: (en.)\)$/\2/p'`

# Determine previous ethernet status
# If file prev_eth_on exists, ethernet was active last time we checked
if [ -f "/var/tmp/prev_eth_on" ]; then
    prev_eth_status="On"
fi

# Determine same for AirPort status
# File is prev_air_on
if [ -f "/var/tmp/prev_air_on" ]; then
    prev_air_status="On"
fi

# Check actual current ethernet status
for eth_name in ${eth_names}; do
    if ([ "$eth_name" != "" ] && [ "`ifconfig $eth_name | grep "status: active"`" != "" ]); then
        eth_status="On"
    fi
done

# And actual current AirPort status
air_status=`/usr/sbin/networksetup -getairportpower $air_name | awk '{ print $4 }'`

# If any change has occured. Run external script (if it exists)
if [ "$prev_air_status" != "$air_status" ] || [ "$prev_eth_status" != "$eth_status" ]; then
    if [ -f "./statusChanged.sh" ]; then
        "./statusChanged.sh" "$eth_status" "$air_status" &
    fi
fi

# Determine whether ethernet status changed
if [ "$prev_eth_status" != "$eth_status" ]; then

    if [ "$eth_status" = "On" ]; then
        set_airport "Off"
    #    growl "Wired network detected. Turning AirPort off."
    else
        set_airport "On"
    #    growl "No wired network detected. Turning AirPort on."
    fi

# If ethernet did not change
else

    # Check whether AirPort status changed
    # If so it was done manually by user
    if [ "$prev_air_status" != "$air_status" ]; then
    set_airport $air_status

    #if [ "$air_status" = "On" ]; then
    #    growl "AirPort manually turned on."
    #else
    #    growl "AirPort manually turned off."
    #fi

    fi

fi

# Update ethernet status
if [ "$eth_status" == "On" ]; then
    touch /var/tmp/prev_eth_on
else
    if [ -f "/var/tmp/prev_eth_on" ]; then
        rm /var/tmp/prev_eth_on
    fi
fi

sleep 10
exit 0