wifi-check

#!/bin/bash
##################################################################
# A Project of TNET Services, Inc
#
# Title:     WiFi_Check
# Author:    Kevin Reed (Dweeber)
#            dweeber.dweebs@gmail.com
# Updated:   R. Pusztai <rjpcomputing@gmail.com>
# Project:   Raspberry Pi Stuff
#
# Copyright: Copyright (c) 2012 Kevin Reed <kreed@tnet.com>
#            https://github.com/dweeber/WiFi_Check
#
# 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_Check
# 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_Check 
#
##################################################################
# Settings
# Where and what you want to call the Lockfile
lockfile='/var/run/wifi-check.pid'
# Which Interface do you want to check/fix
wlan='wlan0'
##################################################################
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
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 $wlan | grep -q "inet addr:" ; then
    echo "Network is Okay"
else
    # Only allow re-connection if the eth0 is not physically connected
    isWireConnected=`cat /sys/class/net/eth0/operstate`
    if [ "$isWireConnected" == "down" ]; then
        echo "Network connection down! Attempting reconnection."
        ifdown $wlan
        sleep 5
        ifup --force $wlan
        ifconfig $wlan | grep "inet addr"
    else
        echo "Network connection down, but not reconnecting because eth0 is connected and configuring device."
    fi
fi

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

##################################################################
# End of Script
##################################################################