Get hop count the host (without traceroute)

get-hops.sh

#!/bin/bash

DEST=${1:-8.8.8.8}
MAXHOP=${2:-31}
IPV="-4"

# Ctrl + Cで中断
trap 'echo Breaked; exit 2' 2

# そもそも届かなければ終了
if ! ping -c 1 "${IPV}" "${DEST}" > /dev/null; then
  echo "Cannot connect to ${DEST}"
  exit 1
fi

# 2分探索
MAX=`expr ${MAXHOP} + 1`
MIN=1
while [ $MIN -lt $MAX ]
do
  i=`expr '(' $MIN + $MAX ')' / 2`
  echo -ne "(current, min, max) = ($i , $MIN , $MAX)\t" >&2
  if ping -c 1 -t $i "${IPV}" "${DEST}" > /dev/null; then
    echo "Reached" >&2
    MAX=$i
  else
    echo "Didn't reach" >&2
    MIN=`expr $i + 1`
  fi
done

if [ "$MAX" -gt "${MAXHOP}" ]; then
  echo "Hop count exceed ${MAXHOP}"
  exit 1
fi

echo $MAX