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Re: grep: show matching line from pattern file

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On 2022-05-28 at 15:40, Jim Popovitch wrote:

> Not exactly Debian specific, but hoping that someone here can help.
> 
> I have a file of regex patterns and I use grep like so:
> 
>    ~$ grep -f patterns.txt /var/log/syslog 
> 
> What I'd like to get is a listing of all lines, specifically the line
> numbers of the regexps in patterns.txt, that match entries in
> /var/log/syslog.   Is there a way to do this?

I don't know of a standardized way to do that (if anyone else wants to
suggest one, I'm open to learn), but of course it *can* be done, via
scripting. Off the top of my head, I came up with the following

for line in $(seq 1 $(wc -l patterns.txt | cut -d ' ' -f 1)) ; do
  if grep $(head -n $line patterns.txt | tail -n 1) /var/log/syslog >
/dev/null ; then
    echo $line ;
  fi
done

I just tested that on my own system, with a different file (since I'm
not root right now) and a couple of exact-string patterns found by
examining that file, and it seems to work as intended. YMMV.

-- 
   The Wanderer

The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore all
progress depends on the unreasonable man.         -- George Bernard Shaw

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Thread

grep: show matching line from pattern file Jim Popovitch <jim@k4vqc.com> - 2022-05-28 22:00 +0200
  Re: grep: show matching line from pattern file The Wanderer <wanderer@fastmail.fm> - 2022-05-28 22:10 +0200
    Re: grep: show matching line from pattern file Greg Wooledge <greg@wooledge.org> - 2022-05-28 23:20 +0200
      Re: grep: show matching line from pattern file The Wanderer <wanderer@fastmail.fm> - 2022-05-28 23:30 +0200
      Re: grep: show matching line from pattern file Jim Popovitch <jim@k4vqc.com> - 2022-05-29 19:50 +0200
      Re: grep: show matching line from pattern file Will Mengarini <seldon@eskimo.com> - 2022-06-03 00:30 +0200
        Re: grep: show matching line from pattern file David Christensen <dpchrist@holgerdanske.com> - 2022-06-03 01:00 +0200
          Re: grep: show matching line from pattern file Will Mengarini <seldon@eskimo.com> - 2022-06-03 02:20 +0200
  Re: grep: show matching line from pattern file Jörg-Volker Peetz <jvpeetz@web.de> - 2022-05-29 15:10 +0200
    Re: grep: show matching line from pattern file David Wright <deblis@lionunicorn.co.uk> - 2022-05-29 15:50 +0200
      Re: grep: show matching line from pattern file duh <fill_in_the_blanks@email.com> - 2022-06-02 21:20 +0200
        Re: grep: show matching line from pattern file Greg Wooledge <greg@wooledge.org> - 2022-06-02 21:20 +0200
          Re: grep: show matching line from pattern file Richard Hector <richard@walnut.gen.nz> - 2022-06-04 05:00 +0200

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