Hello dideod.yang,

Fellow Monks have answered your question but I wanted to add another possible solution, not more efficient but just for fun. See sample of code bellow:

#!/usr/bin/perl
use strict;
use IO::All;
use warnings;
use Data::Dumper;
use List::Util 'first';

my @lines = io($ARGV[0])->chomp->slurp;
print Dumper \@lines;
my $match = first { /test/ } @lines;
print 'First Found: ' . $match . "\n";

__END__

$ perl sample.pl file.txt
$VAR1 = [
          'This is line one',
          'This is line two',
          'This is line three with test key word',
          'This is line four with test key word'
        ];
First Found: This is line three with test key word
[download]

I am using the following two modules IO::All and List::Util::first. The first modules it is loading the lines on an array, the second module will stop searching the array when it will find the first match.

Hope this helps, BR.