WiFi Monitor - Restart WiFi

wifi_monitor.sh

#!/bin/bash
##################################################################
#
# Purpose:
#
# Script checks to see if WiFi has a network IP and if not
# restart WiFi
#
# Uses a lock file which prevents the script from running more
# than one at a time.  If lockfile is old, it removes it
#
# Instructions:
#
# o Install where you want to run it from like /usr/local/bin
# o chmod 0755 /usr/local/bin/wifi_monitor.sh
# o Add to crontab
#
# Run Every 5 mins - Seems like ever min is over kill unless
# this is a very common problem.  If once a min change */5 to *
# once every 2 mins */5 to */2 ... 
#
# */5 * * * * /usr/local/bin/wifi_monitor.sh 
#
##################################################################
# Settings
# Where and what you want to call the Lockfile
lockfile='/tmp/wifi_monitor.pid'
# Which Interface do you want to check/fix
wlan='wlan0'
##################################################################
echo
echo "Starting WiFi check for $wlan"
date
echo 

# Check to see if there is a lock file
if [ -e $lockfile ]; then
    # A lockfile exists... Lets check to see if it is still valid
    pid=`cat $lockfile`
    if kill -0 &>1 > /dev/null $pid; then
        # Still Valid... lets let it be...
        # echo "Process still running, Lockfile valid"
        exit 1
    else
        # Old Lockfile, Remove it
        # echo "Old lockfile, Removing Lockfile"
        rm $lockfile
    fi
fi
# If we get here, set a lock file using our current PID#
# echo "Setting Lockfile"
echo $$ > $lockfile

# We can perform check
echo "Performing Network check for $wlan"
if ifconfig $wlan | grep -q "inet addr:" ; then
    echo "Network is Okay"
else
    echo "Trying Network connection Up! Attempting reconnection."
    sudo ifup --force $wlan
    sleep 15
    echo `ifconfig $wlan | grep "inet addr"`
fi

sleep 5
echo 
echo "Current Setting:" 
echo `ifconfig $wlan | grep "inet addr:"`
echo
 
# Check is complete, Remove Lock file and exit
# echo "process is complete, removing lockfile"
rm $lockfile
exit 0