Re: extracting an IPv4 address from text?

On Sat, 2 Apr 2022, 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?

How about:

cat auth.log | tr " " "\n" | grep "\." | grep -v "\[" | grep -v "[a-zA-Z]"

or something similar, although I am sure there will be a few strays slip 
through.

Daniel Feenberg