Checks a pingable source and reboots the host when the failure limit is reached.

rpi-network-watchdog.sh

#!/bin/bash
#
# Original Source Attribution:
# Location: https://gist.github.com/SandroMachado/87e591fc42f368636b251b566485ae46
# Author: Sandro Machado
# Date of retrieval: 2019-05-28
#
# Script Summary:
# This script checks a pingable source and when the failure
# limit is reached the host is restarted.  No files are written
# to with this script.
#
# This script is intended to be ran via cron with the @reboot
# (see man 5 crontab) option so that it runs once at startup and
# continues execution in an infinite loop until a reboot
# condition is reached.
#
# Modifications the original source are made under the following license:
#
# MIT License
#
# Copyright (c) 2019 Tyler B. Long
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
#

####################
# Configurations
####################

# The interval [sec] to check the pingable destination for connectivity.
check_interval=120

# The public or local resource to ping.
ping_destination=10.189.200.1

# The number of ping packets to send.
ping_count=3

# The consecutive max ping failure count. When reached a reboot is invoked.
max_ping_failures=5

####################
# Main
####################

failure_count=0

while true
do
    
    # test the pingable resource
    ping -c $ping_count $ping_destination > /dev/null 2>&1
    
    # check exit status of ping command
    if [[ $? -eq 0 ]]; then
        failure_count=0
    else
        failure_count=$((failure_count+1))
        if ((failure_count >= max_ping_failures)); then
            sudo /sbin/shutdown -r +1
            break
        fi
    fi
    
    sleep $check_interval
    
done