A rough Bash script from my Linux server class to ping all the IP addresses on our network

Ping-LocalNetwork.sh

#!/bin/bash

# Set the internal field separator
IFS=$'\n'

ping_count=3
ping_deadline=1

# regex pattern for IP addresses
grep_ip="[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}"

# Get the interface used for the internet (probably also used for LAN)
# does not open any connection out, it just shows the route needed to get to Google's DNS.
my_interface=$(ip route get 8.8.8.8 | grep -oP "dev [a-zA-Z0-9]* " | cut -d " " -f 2)
# Get the IP address assigned to that interface
ip_netmask=$(ip addr show "$my_interface" | grep -oP "$grep_ip/[0-9]{1,2}")

printf "network %s accessible on %s\n" "$ip_netmask" "$my_interface"

network_bits=$(echo "$ip_netmask" | cut -d "/" -f 2)

# # # #

if [ $network_bits -eq 8 ]
then
        network_address=$(echo "$ip_netmask" | cut -d "." -f 1)
fi

if [ $network_bits -eq 12 ]
then
        network_address=$(echo "$ip_netmask" | cut -d "." -f 1-2)
fi

if [ $network_bits -eq 24 ]
then
        network_address=$(echo "$ip_netmask" | cut -d "." -f 1-3)
fi

printf "%s\n\n" "$network_address"

# # # #

if [ $network_bits -eq 8 ]
then
        for ip in $network_address.{1..254}.{1..254}.{1..254}
        do
                printf "Trying %s " "$ip"
                ping -q -f -w "$ping_deadline" -c "$ping_count" "$ip" | grep rtt
                printf "\n"
        done
fi

if [ $network_bits -eq 12 ]
then
        for ip in $network_address.{1..254}.{1..254}
        do
                printf "Trying %s " "$ip"
                ping -q -f -w "$ping_deadline" -c "$ping_count" "$ip" | grep rtt
                printf "\n"
        done
fi

if [ $network_bits -eq 24 ]
then
        for ip in $network_address.{1..254}
        do
                printf "Trying %s " "$ip"
                ping -q -f -w "$ping_deadline" -c "$ping_count" "$ip" | grep rtt
                printf "\n"
        done
fi

# # # #

unset IFS