CODEWITHSUNDEEP
pythonregex
user4093955
user4093955

Reputation:

Is there a better way than double parsing the string?

I'm parsing an iptables' log file seeking for the source IPs. To do so, I'm using two instances of re.findall, one for finding "SRC=x.x.x.x" and the other for actually getting the IP. 

for line in iptables:
    src = re.findall('SRC=\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}', line)
    ip = re.findall('\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}', src)

Is there a better way to achieve the same result? That is, just getting the SRC IP.

For what I want to do right now it really doesn't matter, but I'd like to know whether are there better methods of achieving the same for future development.

Upvotes: 2

Views: 59

Answers (1)

tobias_k
tobias_k

Reputation: 82899

You should put the IP-part into a group, i.e. inside parentheses. This way, you can search a match and get the group inside that match.

>>> line = "SRC=127.0.0.1"
>>> m = re.search(r'SRC=(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})', line)
>>> m.group(0)
'SRC=127.0.0.1'
>>> m.group(1)
'127.0.0.1'

Here, group(0) is the entire match, group(1) the part enclosed in the first set of (), and so on.

Upvotes: 3

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