尝试ping命令判断主机的存活状态

```
#!/bin/bash
#ping.sh
#Auther:stone
#取起始IP
read -p "please input start IPadr:" startip
#判断输入的是否为IP地址
while :; do
echo $startip |grep -E '\<([1-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\>\.\<([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\>\.\<([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\>\.\<([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\>' && break
      read -p "please input IPadr(192.168.1.1)：" startip

done
#结束IP	
read -p "please input end   IPadr:" endip
#判断结束IP的格式是否正确
while :; do
echo $endip |grep -E '\<([1-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\>\.\<([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\>\.\<([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\>\.\<([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\>' && break 
      read -p "please input end IPadr(192.168.1.255)" endip
done

#判断结束IP段是否大于起始IP段,有四种可能：
if [ $tail1 -lt $head1 ]; then
    echo -e "\033[31mend IPadr smaller than start IPadr.\033[0m"
    exit 10 
fi

if [ $tail1 -lt $head1 ] && [ $tail2 -lt $head2 ]; then
    echo -e "\033[31mend IPadr smaller than start IPadr.\033[0m"
    exit 10 
fi

if [ $tail1 -lt $head1 ] && [ $tail2 -lt $head2 ] && [ $tail3 -lt $head3 ]; then
    echo -e "\033[31mend IPadr smaller than start IPadr.\033[0m"
    exit 10 
fi

if [ $tail1 -lt $head1 ] && [ $tail2 -lt $head2 ]  && [ $tail3 -lt $head3 ] && [ $tail4 -lt $head4 ]; then
    echo -e "\033[31mend IPadr smaller than start IPadr.\033[0m"
    exit 10 
fi

#以下为ping命令循环
while :; do
  if [ $head1 -eq $tail1 ]; then
     if [ $head2 -eq $tail2 ]; then
        if [ $head3 -eq $tail3 ]; then
           for ((d=$head4;d<=$tail4;d++)); do
              ping -c 1 -W 1 $head1.$head2.$head3.$d &>/dev/null   
              [ $? == 0 ] && echo -e "\033[32m$head1.$head2.$head3.$d is up.\033[0m"
              [ $? == 1 ] && echo -e "\033[31m$head1.$head2.$head3.$d id down.\033[0m"
           done
                  exit 0
        else
           for ((d=$head4;d<=255;d++)); do
              ping -c 1 -W 1 $head1.$head2.$head3.$d &>/dev/null    
              [ $? == 0 ] && echo -e "\033[32m$head1.$head2.$head3.$d is up.\033[0m"
              [ $? == 1 ] && echo -e "\033[31m$head1.$head2.$head3.$d id down.\033[0m"
           done
           declare c=$head3
           let c++
           while (($tail3-$c>0)); do
              for ((d=1;d<=255;d++)); do
              ping -c 1 -W 1 $head1.$head2.$c.$d &>/dev/null    
              [ $? == 0 ] && echo -e "\033[32m$head1.$head2.$c.$d is up.\033[0m"
              [ $? == 1 ] && echo -e "\033[31m$head1.$head2.$c.$d id down.\033[0m"
              done
           done
           if [ `expr $tail3 - $c` -eq 0 ]; then
              for ((d=0;d<=$tail4;d++)); do
              ping -c 1 -W 1 $head1.$head2.$c.$d &>/dev/null    
              [ $? == 0 ] && echo -e "\033[32m$head1.$head2.$c.$d is up.\033[0m"
              [ $? == 1 ] && echo -e "\033[31m$head1.$head2.$c.$d id down.\033[0m"
              done
              exit 0
           fi
        fi
     fi
  fi
done
```

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