To better help you, it helps us to see your code.

Can you please post the code you have and tell us how that code fails to do what you need?

to make a program you must have a plain solution to then translate it into a program. Let's see:

open a file named DATA.TXT
read all lines of this file
if the string 'NINE' is found save the whole string for later use
   -or (not clear in your question)-
if the string 'NINE' is found split this string into 8 parts
close the file
print the result
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useful reads:

• https://perldoc.perl.org/perlintro.html
• https://perldoc.perl.org/perlopentut.html especially this part
• while or foreach to cycle the file (always in perlintro)
• chomp to remove the newline while reading
• conditional loop inside perlintro
• basics regexes inside perlintro

Dont forget to start your program with:

use strict;
use warnings;
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You can also add use diagnostics; after the above lines to get more help from Perl itself

L*

Thanks for this inputs. I will try my own code and learn from there

G'day saro,

Welcome to the Monastery.

I suspect there's more to this than you're telling us; however, based on what you have provided, I'd probably aim for a technique such as this:

#!/usr/bin/env perl

use strict;
use warnings;

my $flag = 'NINE';

while (<DATA>) {
    print if (split)[0] eq $flag;
}

__DATA__
DATA.TXT
==============
ONE TWO THREE FOUR FIVE SIX SEVEN EIGHT
NINE TEN ELEVEN TWELEVE 12-MAR-2020 /net/slcnas22/scratch/domain_name 
+http://testurl/home username_pwd
THIRTEEN FOURTEEN FIFTEEN
SIXTEEN SEVENTEEN EIGHTEEN NINETEEN TWENTY
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Output:

NINE TEN ELEVEN TWELEVE 12-MAR-2020 /net/slcnas22/scratch/domain_name 
+http://testurl/home username_pwd
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I see that ++Discipulus has provided a number of good documentation links; although, this technique does not require chomp nor does it use regexes. I also suggest you look at the autodie pragma: I highly recommend it.

To further clarify, what should the output be from lines like

NINETY ALANINE one two three four five six seven
xx yy NINE one two three four five six seven
xx yy NINE one NINE three four five six seven
NINE one two three four five six seven eight nueve ten
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Also, I tend to think of a line read from a file as a single string. You seem to be referring to the non-whitespace substrings of your example strings as "strings". Do you want the non-whitespace substrings of a line containing your target string to be split out as an array or list of individual strings, or is it sufficient to simply return the whole line?

In addition to the documentation links already given, please see perlre, perlretut, and perlrequick, and Short, Self-Contained, Correct Example and maybe How to ask better questions using Test::More and sample data.