Matching pattern over multiple lines in Python

Question

I am new to Python regex. I trying to get below lst from the output.

output="""
IP = 10.10.10.1
BGP version 4, remote router ID 0.0.0.0
State = Established
IP = 10.10.10.2
BGP version 4, remote router ID 0.0.0.0
State = Active
IP = 10.10.10.3
BGP version 4, remote router ID 0.0.0.0
State = Active
IP = 10.10.10.4
BGP version 4, remote router ID 0.0.0.0
State = Established
"""

I am trying with below regex but no luck. Can someone please help me.

lst = re.findall(r'IP = (\S+)\n\nState = (\S+)',output, re.M)

lst should be filled with

[('10.10.10.1', 'Established'), ('10.10.10.2', 'Active'), ('10.10.10.3', 'Active'), ('10.10.10.4', 'Established')]

Use re.findall(r'(?sm)^IP = (\S+).*?^State = (\S+)',output) if your input is well formatted and there is a State for each IP. — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Aug 19, 2017 at 17:39
@WiktorStribiżew What is for (?sm). Could you please let me know ? — dpd
– dpd, Commented Aug 19, 2017 at 17:46

MaxU - stand with Ukraine · Accepted Answer · 2017-08-19 17:56:23Z

2

Try this:

In [101]: pat = r'IP\s*\=\s*([^\n\r]*)[\r\n][^\=]*?State\s*\=\s*([^\n\r]*)'

In [102]: re.findall(pat, output, flags=re.M & re.S)
Out[102]:
[('10.10.10.1', 'Established'),
 ('10.10.10.2', 'Active'),
 ('10.10.10.3', 'Active'),
 ('10.10.10.4', 'Established')]

NOTE: please pay attention at @WiktorStribiżew's RegEx, which is much more elegant:

re.findall(r'(?sm)^IP = (\S+).*?^State = (\S+)',output)

edited Aug 19, 2017 at 17:56

answered Aug 19, 2017 at 17:33

MaxU - stand with Ukraine

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6 Comments

Błotosmętek Over a year ago

Why [\r\n]? As far as I know, all Unix systems use just \n, while Microsoft uses a sequence \r\n, but nobody uses \r alone.

MaxU - stand with Ukraine Over a year ago

@Błotosmętek, yes, but in [] RegEx we specify a list of symbols in any order... ;-)

Wiktor Stribiżew Over a year ago

@Błotosmętek \r is a MacOS line break style.

Błotosmętek Over a year ago

Yes, I know how [] works - [\r\n] matches either \n (Unix) or \r (???); it does not match \r\n (Microsoft) though… care to explain?

Błotosmętek Over a year ago

@WiktorStribiżew funny, I thought MacOS X uses \n like all other Unix variants…

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