$ cat infile1.txt
line1
line3
line2
line1
line3
line4
line2
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#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;

my %hash;
my $myfile = '/dir/subdir/infile1.txt'; 

open( my $in, '<', $myfile) or die "Can't open $myfile: $!"; 
map { chomp; $hash{ $_ }++ } <IN>;
close($in);
print Dumper \%hash;
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Output:
$VAR1 = {
          'line3' => 2,
          'line2' => 2,
          'line4' => 1,
          'line1' => 2
        };
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hth,

PooLpi

Update : chomp