Get all text between a specified string with regex

Question

How can I get a string between 2 specified strings in Python3 using regex?

b'SSH-2.0-OpenSSH_6.6.1p1 Ubuntu-2ubuntu2.11\r\n'

desired output:

>>> SSH-2.0-OpenSSH_6.6.1p1 Ubuntu-2ubuntu2.11

# ipsort.py
import re

f = open("ssh.txt", "r")

line = f.readline()

for line in f:
    version = re.search(r"b'(.*?)\r\n'", line)
    new_file = open("ssh_versions.txt", "a")
    new_file.write(version)
    new_file.close()

Traceback (most recent call last):
  File "ipsort.py", line 11, in <module>
    new_file.write(version)
TypeError: write() argument must be str, not None

In general, use `string1(.*?)string2` and then get capture group 1. — Barmar, May 01 '20 at 14:24
I was having problems with the backslash being an escape character — j86h, May 01 '20 at 14:25
That's why you should always use a raw string when creating a regexp. — Barmar, May 01 '20 at 14:26
I'm reasonably new to Python and very new to regular expressions, what exactly do you mean by always use a raw string? — j86h, May 01 '20 at 14:29
See https://stackoverflow.com/questions/12871066/what-exactly-is-a-raw-string-regex-and-how-can-you-use-it — Barmar, May 01 '20 at 14:30
yes I'm still stuck. Referring to other resources is what I've been doing for hours but I still cant do it, I keep getting errors. A straight answer with a code example would be appreciated. — j86h, May 01 '20 at 16:41

score 1 · Accepted Answer · answered May 01 '20 at 17:01

1

You need to double the \ in the regexp, because otherwise it's matching CR and LF characters rather than literal \r and \n.

You also need to use version.group(1) to get the string that the capture group matched.

version = re.search(r"b'(.*?)\\r\\n'", line)
if version:
    with open("ssh_versions.txt", "a") as new_file:
        new_file.write(version.group(1))

answered May 01 '20 at 17:01

Barmar

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Thank you, it works. It was seriously frustrating. Regular expressions are complicated, its like learning a new language. – j86h May 01 '20 at 17:15

Get all text between a specified string with regex

1 Answers1