Search code examples
pythonregexattributeerror

Workaround no Variable Read in From Regex Search


I'm trying to print out strings that are read in from a regex expression. For some of the lines of text being read in with my regex search, there is no data, so there isn't anything to read in. When this occur, I get the error, "AttributeError: 'NoneType' object has no attribute 'group'. Could anyone help me write a work around in my code so that when nothing is read in from the regex search, the variable isn't printed out? I tried if (col3.group() != None):, but that doesn't seem to work.

#!/usr/bin/env python

#purpose of script: To conduct an nslookup on a list of IP addresses

import os, csv, re

#get list of IP's from file
inFile='filesystem/Book1.txt'
ipList = []
with open(inFile, 'rb') as fi:
    for line in fi: 
        line = line.replace(',', '')#remove commas and \n from list
        line = line.replace('\r', '')
        line = line.replace('\n', '')
        ipList.append(line)# create list of IP addresses to lookup

#output results
outFile='filesystem/outFile.txt'
fo = open(outFile, 'w')
inc=0
writeToFileValue = ""
for e in ipList:
    result = os.popen('nslookup ' + e).read()#send nsLookup command to cmd prompt

    col1 = re.search(r'Server:.*', result, re.M|re.I)#use regex to extract data
    col2 = re.search(r'Address:  8.8.8.8', result, re.M|re.I)
    col3 = re.search(r'Name:.*', result, re.M|re.I)
    col4 = re.search(r'Address:  (?!8.8.8.8).*', result, re.M|re.I) 

    print col1.group()
    print col2.group()
    if (col3.group() != None):
        print col3.group() # if none, skip
    if (col4.group() != None):
        print col4.group() # if none, skip

Solution

  • instead of this:

       if (col3.group() != None):
            print col3.group() # if none, skip
    

    do this:

       try col3.group():
            print col3.group()
       except AttributeError:
            pass