python parse file for ip addresses

Question

I have a file with several IP addresses. There are about 900 IPs on 4 lines of txt. I would like the output to be 1 IP per line. How can I accomplish this? Based on other code, I have come up wiht this, but it fails becasue multiple IPs are on single lines:

import sys
import re

try:
    if sys.argv[1:]:
        print "File: %s" % (sys.argv[1])
        logfile = sys.argv[1]
    else:
        logfile = raw_input("Please enter a log file to parse, e.g /var/log/secure: ")
    try:
        file = open(logfile, "r")
        ips = []
        for text in file.readlines():
           text = text.rstrip()
           regex = re.findall(r'(?:[\d]{1,3})\.(?:[\d]{1,3})\.(?:[\d]{1,3})\.(?:[\d]{1,3})$',text)
           if regex is not None and regex not in ips:
               ips.append(regex)

        for ip in ips:
           outfile = open("/tmp/list.txt", "a")
           addy = "".join(ip)
           if addy is not '':
              print "IP: %s" % (addy)
              outfile.write(addy)
              outfile.write("\n")
    finally:
        file.close()
        outfile.close()
except IOError, (errno, strerror):
        print "I/O Error(%s) : %s" % (errno, strerror)

Answer 1

The $ anchor in your expression is preventing you from finding anything but the last entry. Remove that, then use the list returned by .findall():

found = re.findall(r'(?:[\d]{1,3})\.(?:[\d]{1,3})\.(?:[\d]{1,3})\.(?:[\d]{1,3})',text)
ips.extend(found)

re.findall() will always return a list, which could be empty.

• if you only want unique addresses, use a set instead of a list.
• If you need to validate IP addresses (including ignoring private-use networks and local addresses), consider using the ipaddress.IPV4Address() class.