JayBrown · May 13, 2020 03:55 · May 13, 2020 · May 13, 2020 · May 13, 2020 · May 12, 2020
diff --git a/wifi-auto-switch.zsh b/wifi-auto-switch.zsh
@@ -45,7 +45,7 @@ rssi_threshold_24="15" # signal strength difference threshold below which to swi
 # NOTE: threshold values can be identical!
 pw_50ghz="myPassword1" # 5.0 GHz network passphrase
 pw_24ghz="myPassword2" # 2.4 GHz network passphrase
-# NOTE: escape '$' (string/dollar) characters in passphrases with a '\' (backslash)!
+# NOTE: escape '$' (string/dollar) characters with '\' (backslash) in passphrases!
 ##################################
 
 # macOS airport CLI location

diff --git a/wifi-auto-switch.zsh b/wifi-auto-switch.zsh
@@ -1,7 +1,8 @@
 #!/bin/zsh
 # shellcheck shell=bash
 
-# wifi-auto-switch.zsh v0.2
+# wifi-auto-switch.zsh for macOS
+# v0.2
 
 emulate -LR bash
 export LANG=en_US.UTF-8

diff --git a/wifi-auto-switch.zsh b/wifi-auto-switch.zsh
@@ -1,7 +1,9 @@
 #!/bin/zsh
+# shellcheck shell=bash
 
-# wifi-auto-switch.zsh v0.1
+# wifi-auto-switch.zsh v0.2
 
+emulate -LR bash
 export LANG=en_US.UTF-8
 
 # switch WiFi network function
@@ -37,8 +39,8 @@ suffix_50ghz=".5" # suffix for 5.0 GHz SSID
 suffix_24ghz=".2.4" # suffix for 2.4 GHz SSID
 bssid_5p0ghz="00:00:00:00:00:00" # 5.0 GHz BSSID
 bssid_2p4ghz="00:00:00:00:00:00" # 2.4 GHz BSSID
-rssi_threshold_50="20" # threshold above which to switch to 2.4 GHz
-rssi_threshold_24="10" # threshold below which to switch back to 5.0 GHz
+rssi_threshold_50="20" # signal strength difference threshold above which to switch to 2.4 GHz
+rssi_threshold_24="15" # signal strength difference threshold below which to switch back to 5.0 GHz
 # NOTE: threshold values can be identical!
 pw_50ghz="myPassword1" # 5.0 GHz network passphrase
 pw_24ghz="myPassword2" # 2.4 GHz network passphrase
@@ -87,7 +89,7 @@ rssi24=$(echo "$scan_ssid" | grep "$bssid_2p4ghz" | awk -F"$bssid_2p4ghz" '{prin
 echo -e "Current 5 GHz RSSI: $rssi50\nCurrent 2.4 GHz RSSI: $rssi24"
 
 # RSSI difference between 5.0 & 2.4 GHz # always subtract 5.0 from 2.4 because 2.4 GHz is usually stronger
-rssi_diff=$(expr $rssi24 - $rssi50 | tr -d -c 0-9)
+rssi_diff=$(echo "$rssi24 - $rssi50" | bc | tr -d -c 0-9)
 echo "RSSI difference: $rssi_diff"
 
 # check for network switching
@@ -111,6 +113,4 @@ elif $net24 ; then
 		echo "Value is below threshold: switching WiFi network..."
 		_switchwifi 50
 	fi
-fi
-
-
+fi
diff --git a/wifi-auto-switch.zsh b/wifi-auto-switch.zsh
@@ -49,7 +49,7 @@ pw_24ghz="myPassword2" # 2.4 GHz network passphrase
 airport="/System/Library/PrivateFrameworks/Apple80211.framework/Versions/A/Resources/airport"
 
 # current WiFi status
-bssid_current=$(airport -I | awk '/BSSID:/{print $2}')
+bssid_current=$("$airport" -I | awk '/BSSID:/{print $2}')
 if [[ $bssid_current == "$bssid_5p0ghz" ]] ; then
 	echo "Current BSSID: $bssid_5p0ghz [5 GHz]"
 	net50=true

diff --git a/wifi-auto-switch.zsh b/wifi-auto-switch.zsh
@@ -0,0 +1,116 @@
+#!/bin/zsh
+
+# wifi-auto-switch.zsh v0.1
+
+export LANG=en_US.UTF-8
+
+# switch WiFi network function
+_switchwifi () {
+	# get WiFi device identifier (often 'en0')
+	wifidevice=$(networksetup -listnetworkserviceorder | grep "^(Hardware Port: Wi-Fi," | rev | awk '{print $1}' | rev | sed 's/)$//')
+	if ! [[ $wifidevice ]] ; then
+		echo "Error: WiFi device not found!" >&2
+	else # switch network
+		error=false
+		if [[ $1 == 24 ]] ; then # switch to 2.4 GHz network
+			echo "Switching to 2.4 GHz network..."
+			if ! networksetup -setairportnetwork "$wifidevice" "$ssid_base$suffix_24ghz" "$pw_24ghz" ; then
+				error=true
+			fi
+		elif [[ $1 == 50 ]] ; then # switch to 5.0 GHz network
+			echo "Switching to 5.0 GHz network..."
+			if ! networksetup -setairportnetwork "$wifidevice" "$ssid_base$suffix_50ghz" "$pw_50ghz" ; then
+				error=true
+			fi
+		fi
+		if $error ; then
+			echo "Error switching WiFi network!" >&2
+		fi
+	fi
+}
+
+##################################
+######### USER VARIABLES #########
+##################################
+ssid_base="MyNetwork" # basename of the WiFi's SSID (without suffixes)
+suffix_50ghz=".5" # suffix for 5.0 GHz SSID
+suffix_24ghz=".2.4" # suffix for 2.4 GHz SSID
+bssid_5p0ghz="00:00:00:00:00:00" # 5.0 GHz BSSID
+bssid_2p4ghz="00:00:00:00:00:00" # 2.4 GHz BSSID
+rssi_threshold_50="20" # threshold above which to switch to 2.4 GHz
+rssi_threshold_24="10" # threshold below which to switch back to 5.0 GHz
+# NOTE: threshold values can be identical!
+pw_50ghz="myPassword1" # 5.0 GHz network passphrase
+pw_24ghz="myPassword2" # 2.4 GHz network passphrase
+# NOTE: escape '$' (string/dollar) characters in passphrases with a '\' (backslash)!
+##################################
+
+# macOS airport CLI location
+airport="/System/Library/PrivateFrameworks/Apple80211.framework/Versions/A/Resources/airport"
+
+# current WiFi status
+bssid_current=$(airport -I | awk '/BSSID:/{print $2}')
+if [[ $bssid_current == "$bssid_5p0ghz" ]] ; then
+	echo "Current BSSID: $bssid_5p0ghz [5 GHz]"
+	net50=true
+	net24=false
+elif [[ $bssid_current == "$bssid_2p4ghz" ]] ; then
+	echo "Current BSSID: $bssid_2p4ghz [2.4 GHz]"
+	net50=false
+	net24=true
+else
+	echo "Not connected to home WiFi! Exiting..."
+	exit
+fi
+
+# WiFi environment scan
+while true
+do
+	scan_all=$("$airport" -s 2>/dev/null)
+	scan_ssid=$(echo "$scan_all" | grep "$ssid_base")
+	if ! [[ $scan_ssid ]] ; then
+		echo "Home WiFi network '$ssid_base' not detected! Exiting..."
+		exit
+	else
+		if [[ $(echo "$scan_ssid" | wc -l) == 1 ]] ; then
+			echo "Only one home WiFi network detected! Exiting..."
+			exit
+		else
+			break
+		fi
+	fi
+done
+
+# RSSI values (signal strength)
+rssi50=$(echo "$scan_ssid" | grep "$bssid_5p0ghz" | awk -F"$bssid_5p0ghz" '{print substr($0, index($0,$2))}' | awk '{print $1}' | tr -d -c 0-9)
+rssi24=$(echo "$scan_ssid" | grep "$bssid_2p4ghz" | awk -F"$bssid_2p4ghz" '{print substr($0, index($0,$2))}' | awk '{print $1}' | tr -d -c 0-9)
+echo -e "Current 5 GHz RSSI: $rssi50\nCurrent 2.4 GHz RSSI: $rssi24"
+
+# RSSI difference between 5.0 & 2.4 GHz # always subtract 5.0 from 2.4 because 2.4 GHz is usually stronger
+rssi_diff=$(expr $rssi24 - $rssi50 | tr -d -c 0-9)
+echo "RSSI difference: $rssi_diff"
+
+# check for network switching
+if $net50 ; then
+	rssi_threshold="$rssi_threshold_50"
+	echo "Threshold: $rssi_threshold"
+	if [[ $rssi_diff -lt "$rssi_threshold" ]] ; then
+		echo "Value is below threshold: exiting..."
+		exit
+	else # on 5.0 GHz the value needs to be *above* threshold, i.e. decreased strength of 5.0 GHz
+		echo "Value is above threshold: switching WiFi network..."
+		_switchwifi 24
+	fi
+elif $net24 ; then
+	rssi_threshold="$rssi_threshold_24"
+	echo "Threshold: $rssi_threshold"
+	if [[ $rssi_diff -gt "$rssi_threshold" ]] ; then
+		echo "Value is above threshold: exiting..."
+		exit
+	else # on 2.4 GHz the value needs to be *below* threshold, i.e. increased strength of 5.0 GHz
+		echo "Value is below threshold: switching WiFi network..."
+		_switchwifi 50
+	fi
+fi
+
+
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