Date: Sat, 2 Apr 2022 16:57:04 -0700 From: David Christensen <dpchrist@holgerdanske.com> To: questions@freebsd.org Subject: Re: extracting an IPv4 address from text? Message-ID: <3bd9bbf1-d904-b8e1-1595-e19abf75ea48@holgerdanske.com> In-Reply-To: <25160.44484.392802.868667@jerusalem.litteratus.org> References: <25160.44484.392802.868667@jerusalem.litteratus.org>
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On 4/2/22 13:10, Robert Huff wrote:
>
> Hello:
> Let's suppose I want to parse a line from auth.log and extract
> the IP address (if any) to stdout.
> I'm assuming there is a robust way to do this using standard
> command-line tools ... but my brain is flailing on the exact method.
> Anyone have a example they'd be willing to share? Or is this a
> problem already solved?
>
>
> Hopefully,
>
>
> Robert Huff
>
Here is one way [1, 2]:
2022-04-02 15:20:35 toor@f3 ~
# cat /var/log/auth.log | perl -ne '/(\d{1,3}(\.\d{1,3}){3})/; print
"$1\n"' | sort | uniq
192.168.5.11
192.168.5.13
192.168.5.220
192.168.5.76
Note that only the root user can read or write /var/log/auth.log. So,
if a non-root process needs the information, one approach is to use
sudo(8) [3].
David
References:
[1] https://www.oreilly.com/library/view/learning-the-unix/0596002610/
[2] https://www.oreilly.com/library/view/learning-perl-8th/9781492094944/
[3] https://mwl.io/nonfiction/tools#sudo
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