Hi,
make the resultfile inot a lookup hash, then go through the metrics file and check if the key exists:

#!/usr/bin/perl
use strict;
use warnings;

my  $metricsfile = $ARGV[0];
my  $resultfile  = $ARGV[1];

print "MetricsFilename:$metricsfile\n";
print "ResultsFilename:$resultfile\n\n";

my %results;

### Opening the result file to read ####
open( IN, "<$resultfile" ) or die "Can't open $resultfile: $!";

while ( <IN> ) {    
  chomp; # remove newline
  $result{$_}++; # put line into hash as key
}
close IN;


### Opening the metrics file to read ####
open( IN, "<$metricsfile" ) or die "Can't open $metricsfile: $!";

while ( <IN> ) {
  chomp; # remove newline
  if ($result{$_}) {
    print "$_ is in $resultfile\n";
  }
  else {
    print "$_ is NOT in $resultfile\n";
  }
}
close IN;
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