авто переключение dns

#!/bin/bash
if cat /etc/resolv.conf | grep nameserver | grep -o "127" &>/dev/null;
 then if ip a | grep -v "inet6" | grep -v "127.0.0.1" | grep inet | grep -oE '[0-9]{1,3}(\.[0-9]{1,3}){3}' | grep -v ".255" | grep ".1\.[0-9]" | grep -o "[0-9].*" &>/dev/null;
  then echo "nameserver 192.168.1.1" > /etc/resolv.conf
  else if ip a | grep -v "inet6" | grep -v "127.0.0.1" | grep inet | grep -oE '[0-9]{1,3}(\.[0-9]{1,3}){3}' | grep -v ".255" | grep ".10\.[0-9]" | grep -o "[0-9].*" &>/dev/null;
   then echo "nameserver 192.168.10.1" > /etc/resolv.conf
  fi
 fi
fi

if cat /etc/resolv.conf | grep nameserver | grep -o ".1\.[0-9]" | grep -o "[0-9].*" &>/dev/null;
 then if ip a | grep -v "inet6" | grep -v "127.0.0.1" | grep inet | grep -oE '[0-9]{1,3}(\.[0-9]{1,3}){3}' | grep -v ".255" | grep ".10\.[0-9]" &>/dev/null;
  then sudo echo "nameserver 192.168.10.1" > /etc/resolv.conf
 fi
fi

if cat /etc/resolv.conf | grep nameserver | grep -o ".10\.[0-9]" | grep -o "[0-9].*" &>/dev/null;
 then if ip a | grep -v "inet6" | grep -v "127.0.0.1" | grep inet | grep -oE '[0-9]{1,3}(\.[0-9]{1,3}){3}' | grep -v ".255" | grep ".1\.[0-9]" | grep -o "[0-9].*" &>/dev/null;
  then echo "1"
 sudo echo "nameserver 192.168.1.1" > /etc/resolv.conf
 fi
fi