use warnings;
use strict;

my $search = 'blah';

open my $fh, '<', 'file.txt' or die $!;

my @lines = (
    "this is line 1 of aref\n",
    "this is line 2 of aref blah\n",
);

parse_line($fh);
parse_line(\@lines);

sub parse_line {
    my $arg = shift;

    if (ref $arg eq 'GLOB'){
        # file handle

        while (<$arg>){
            if (/$search/){
                print;
                last;
            }
        }
    }
    elsif (ref $arg eq 'ARRAY'){
        # aref

        for (@$arg){
            if (/$search/){
                print "$_\n";
                last;
            }
        }
    }
    else {
        print "unsupported type...\n";
        exit;
    }
}