Re: grep: show matching line from pattern file

[duh <fill_in_the_blanks@email.com>]

On 5/29/22 9:44 AM, David Wright wrote:
> On Sun 29 May 2022 at 15:02:35 (+0200), Jörg-Volker Peetz wrote:
> > Jim Popovitch wrote on 28/05/2022 21:40:
> > > 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?
> > How about this:
> >
> > $ grep -of patterns.txt /var/log/syslog.1 | grep -n -f - patterns.txt
> That will only work for literal patterns, not regex ones.
>
> Cheers,
> David.

I may be missing a lot but I will risk throwing in my 2 cents (which is
no longer worth the proverbial amount with

the current inflation)


$cat -n /var/log/syslog | grep warn

and it found "warn" in the syslog file and provided line numbers. I have
not used the -f option

(but am now aware of it in the pastfrom your post -- thank you. Might
file that away for future use but will not press

my luck at the moment).

My approach  saves me the effort of writing a scriptl. Ahh, the Perl
philosophy of "there is more than one way to do it".