How do I get information after a certain sentence in a txt file?

Question

I have a text file regarding different information about Ip addresses after a test has been completed. I want to print out this information, how?

The text file is called "IPAddressesTEST.log"

a part of the text follows like this

Connected IPv6’s:

(and here is the ipv6 address)

I’ve tried:

with open ('C:/test/IPAddressesTEST.log', "rt") as Ip_Log:
    for l in Ip_Log:
        Ip_Log_Iter = iter(l)
        for lines in Ip_Log_Iter:
            if lines == "Connected IPv6's:":
                x = next(Ip_Log_Iter)
                break
print(x)

Asked By: Icewolf

||

Source

Answer 1

If we assume the "IPAddressesTEST.log" looks like this:

junk 
stuff
Connected IPv6's:
2345:0425:2CA1:0000:0000:0567:5673:23b5
foo
bar
Connected IPv6's:
2392:0411:2CB2:0000:0000:0567:5226:24ba
more stuff
more junk

Then the following will print out the lines immediately following a line containing the string "Connected IPv6’s:"

with open('IPAddressesTEST.log', 'r', encoding='utf-8') as f:
    lines = f.readlines()

for counter, line in enumerate(lines):
    if "Connected IPv6's:" in line:
        print(lines[counter +1].strip())

Output:

2345:0425:2CA1:0000:0000:0567:5673:23b5
2392:0411:2CB2:0000:0000:0567:5226:24ba

Edit

As requested, if you only want the first instance of Connected IPv6's then you don’t need to keep looping through the file so can break as soon as the relevant line is found:

with open('IPAddressesTEST.log', 'r', encoding='utf-8') as f:
    lines = f.readlines()

for counter, line in enumerate(lines):
    if "Connected IPv6's:" in line:
        print(lines[counter +1].strip())
        break

Output:

2345:0425:2CA1:0000:0000:0567:5673:23b5

Notice it’s just the IP address closest to the top of the file

Answered By: PangolinPaws

Answer 2

import re
pattern = "(?<=Connected IPv6's:n)S*"
text = "Connected IPv6's:n2345:0425:2CA1:0000:0000:0567:5673:23b5"
re.findall(pattern,text)

output:

[‘2345:0425:2CA1:0000:0000:0567:5673:23b5’]

Answered By: Sagun Devkota

How do I get information after a certain sentence in a txt file?

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