#!/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