Check if WiFi is still connected on rpi

 #!/bin/bash

gateway='192.168.0.1'

lockfile='/var/run/chk-wifi.pid'

wlan='wlan0'

if [ -e $lockfile ]; then

    echo `date +%F\ %T\ `$0": A lockfile exists... Lets check to see if it is still valid"

    pid=`cat $lockfile`

    if kill -0 &>1 > /dev/null $pid; then

     echo `date +%F\ %T\ `$0": Process still running, Lockfile valid."

     exit 1

    else

     echo `date +%F\ %T\ `$0": Invalid Lockfile, Removing."

     rm $lockfile

    fi

fi

#echo `date +%F\ %T\ `$0": Setting Lockfile"

echo $$ > $lockfile

#echo `date +%F\ %T\ `$0": Performing network check for $wlan"

ping -c2 $gateway 2>&1

rc=$?

if [[ $rc -eq 0 ]] ; then

        echo `date +%F\ %T\ `$0": The network is up."

else

        echo `date +%F\ %T\ `$0": Network down! Attempting reconnection."

        ifdown $wlan

#        echo `date +%F\ %T\ `$0": Cycling rpi3 onboard wifi driver"

        rmmod brcmfmac

        sleep 2

#        echo `date +%F\ %T\ `$0": Most probable cause in rpi1-2 is USB jamming, cycling the power on USB"

#        echo 0 > /sys/devices/platform/soc/20980000.usb/buspower

#        sleep 2

#        echo 1 > /sys/devices/platform/soc/20980000.usb/buspower

#        sleep 1

#        echo `date +%F\ %T\ `$0": Bringing back the WiFi"

        modprobe brcmfmac

        ifup --force $wlan

#        sleep 1

#        echo `date +%F\ %T\ `$0": New IP: $(ifconfig $wlan | grep 'inet addr')"

#        echo `date +%F\ %T\ `$0": "$(hostname -I)

fi

#echo `date +%F\ %T\ `$0": Remove lock & exit"

rm $lockfile

exit 0