Script to check and re-connect WiFi on Raspberry Pi

WiFiCheck

#!/bin/bash
##################################################################
# A Project of TNET Services, Inc
#
# Title:     WiFi_Check
# Author:    Kevin Reed (Dweeber)
#            [email protected]
# Project:   Raspberry Pi Stuff
#
# Copyright: Copyright (c) 2012 Kevin Reed <[email protected]>
#            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'
pingip='192.168.1.1'
##################################################################
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"
/bin/ping -c 2 -I $wlan $pingip > /dev/null 2> /dev/null
if [ $? -ge 1 ] ; then
    echo "Network connection down! Attempting reconnection."
    /sbin/ifdown $wlan
    /bin/sleep 5
    /sbin/ifup --force $wlan
else
    echo "Network is Okay"
fi

echo
echo "Current Setting:"
/sbin/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
##################################################################

Fantastic. Just what I needed. It works perfect for me. Thanks for putting this out there.
Much appreciated.

Exactly what I needed.

I just changed the interface restart function because my RPi use dhcpcd so ifup / ifdown doesn't work:

    /sbin/dhcpcd -n $wlan
    #/sbin/ifdown $wlan
    #/bin/sleep 5
    #/sbin/ifup --force $wlan

Thanks!

Thanks a lot for sharing this!

I also changed the code a bit because for whatever reason ifup and ifdown don't work on my Pi. In my logs I found these errors:

Dec 10 06:30:13 raspberrypi WiFi_Check: ifdown: unknown interface wlan0
Dec 10 06:30:18 raspberrypi WiFi_Check: ifup: unknown interface wlan0

After doing some research I found out that ifconfig will work on my Pi even through ifup and ifdown don't.

echo "Network connection down! Attempting reconnection."
echo "Taking interface down..."
ifconfig $wlan down
# /sbin/ifdown $wlan
sleep 5
echo "Bringing interface up..."
ifconfig $wlan up
# /sbin/ifup --force $wlan

This worked in a test so hopefully will solve my woes!

BTW this is what I did my crontab file so that I would be able to log the output:
*/5 * * * * root /home/pi/Documents/WiFi_Check 2>&1 | logger -t WiFi_Check

Fantastic. Just what I needed. It works perfect for me. Thanks for putting this out there.
Much appreciated.

Newbie here. I'm up and running but lost my WIFI a couple times now. My power is from the generator's battery so when it gets serviced, I lose the WIFI. I'd like to include this check in my program but have no idea how or where to place it. Can anyone give the basic steps to achieve this?

Newbie here. I'm up and running but lost my WIFI a couple times now. My power is from the generator's battery so when it gets serviced, I lose the WIFI. I'd like to include this check in my program but have no idea how or where to place it. Can anyone give the basic steps to achieve this?

Are you saying that when your power goes out to your Pi, and it turns off when it powers back up it is not connecting to WiFi? I don't think that is what this script will help with. but you could try it. How are you accessing your Pi after it powers up?

lockfile='/var/run/WiFi_Check.pid'

what is the meaning of line. I am using mac system so i m unable to go var directory and this code i will run in raspberry pi or in my local system.

please help me