AttributeError: 'NoneType' object has no attribute 'groups'

Question

I don't know how I should ask this question. If I make any mistakes, I would appreciate it if someone could correct them.

I am writing a program in python on Ubuntu. In that program I am struggling to get Mac address of remote machine from its IP address (RaspberryPi), connected to network.

But In actual practice, it is giving me an error:

Traceback (most recent call last): File "Get_MacAddress_from_ip.py", line 9, in <module> mac = re.search(r"([a-fA-F0-9]{2}[:|\-]?){6}", s).groups()[0] AttributeError: 'NoneType' object has no attribute 'groups'

Can anybody guide me on how do I remove this error? My Coding is given below

from Tkinter import *
from subprocess import Popen, PIPE

ip = "192.168.2.34"
username = "pi"
remote_MAC="b8:27:eb:d2:84:ef"
pid = Popen(["arp", "-n", ip], stdout=PIPE)
s = pid.communicate()[0]
mac = re.search(r"([a-fA-F0-9]{2}[:|\-]?){6}", s).groups()[0]
mac = re.search(r"(([a-f\d]{1,2}\:){5}[a-f\d]{1,2})", s).groups()[0]
print mac

try printing the string "s" and print the result of the re.search on it (Without the groups() stuff) — no_name, Feb 16 '15 at 20:02
after adding line `print s`, it print `192.168.2.34 (192.168.2.34) -- no entry` what does it means — Irfan Ghaffar7, Feb 16 '15 at 20:06
@DanielRoseman from one `re.search`, i didn't get full Mac Address — Irfan Ghaffar7, Feb 16 '15 at 20:12
But there can't possibly be any point calling it once, assigning the result to a variable, and then immediately overwriting that variable with the result of the second call. This is exactly the same as if you had never done the first call at all. — Daniel Roseman, Feb 16 '15 at 20:18
@DanielRoseman same program is successfully working on other machines on same network — Irfan Ghaffar7, Feb 16 '15 at 20:20
It might well be, but that doesn't make it any less true that the first call is utterly pointless. — Daniel Roseman, Feb 16 '15 at 20:22

score 1 · Answer 1 · answered Feb 16 '15 at 20:07

1

re.search returns None if there are no matches. Try assigning the result and checking if it is None:

search = re.search(r"([a-fA-F0-9]{2}[:|\-]?){6}", s)
mac = None
if search:
    mac = search.groups()[0]
    # You can also do:
    #mac = search.group(0)
print mac

answered Feb 16 '15 at 20:07

Jmac

308
1
9

i m only getting `ef` from full mac address `b8:27:eb:d2:84:ef` – Irfan Ghaffar7 Feb 16 '15 at 20:13

AttributeError: 'NoneType' object has no attribute 'groups'

1 Answers1