Ping Scan multiple hosts 255.255.0.0 and output alive systems (threads)

ping-scan.sh

#!/bin/bash
# diegargon http/mail:diego.envigo.net
#
# Ping Scan multiple hosts 255.255.0.0 and output alive  systems
# Usage: ./ping-scan.bash 192.168
#

#Start config
ping_path="/usr/bin/fping"
ping_opt=" -t 200 "
ping="$ping_path $ping_opt"
threads="25"
#End config

counter="1"
a="$1"

if [ -z "$BASH_VERSION" ]; then
    echo "This script requires the BASH"
    exit 1
fi


if [ -z "$1" ]
then
        echo "You need specify X.X ip, ex:192.168"
        exit 1
fi

if [ ! -f "$ping_path" ];
then
        echo "$ping_path not exist."
        exit 1
fi

ping_func() {
        trap "exit" int
        for c in {1..254..1}
        do

                $ping $a.$b.$c 2>/dev/null 1>/dev/null
                if [ "$?" = 0 ]
                then
                        echo "$a.$b.$c"

                fi
        done
}

trap "exit" int
for b in {0..254..1}
do
        if [ "$counter" -gt "$threads" ]
        then
                echo "Max threads reach ($threads)... waiting finish"
                wait
                counter=1
                echo "Leaving waiting state"
        fi
        echo "Sending pings to $a.$b network"
        ping_func &
        counter=$((counter+1))
done

exit 0