Another notice, in the first line while(<$DATA>), you don't really want to use names similar to special literals like DATA as your filehandle names, that may lead to confusion in case someone took up to maintain your code since DATA is connected with the special token __DATA__, read perldata->special literals and SelfLoader.

Where does your while loop end? How did the %Hash_filenames come to existence? Depending on a test sample of your file names that you're searching, what do you expect each one of the hashes you've used to contain?

When you say only the last file 'data' is getting saved in the hash, is 'data' reflective of the file name or the file contents? in both cases however, you may be experiencing this because something is getting overwritten with every iteration of the loop ...

I tried cleaning up your code a little bit to get it working but I don't have any parameters to reproduce the behavior you're describing

#!/usr/local/bin/perl
use strict;
use warnings;
use Data::Dump qw/pp/;

my %seen_file;
my %Hash_filematches;
my %Hash_filenames;

while ( chomp(my $line = <DATA>)){
        (my $file_name) = $line;
        if ( ($file_name) and ( !$seen_file{$file_name}++ ) ) {
        foreach my $filename(keys %Hash_filenames) {
        print "FILE NAME $file_name\n";
      @{ $Hash_filematches{ $filename } } = grep( /\/\Q$file_name\E#/i
+, @{ $Hash_filenames{ $filename } });
     #@{ $Hash_filematches{ $filename } } = grep( (/\/\Q$file_name\E#/
+i && !/\.plf/), @{ $Hash_filenames{ $filename } });--------->@{ $Hash
+_filematches{ $filename } } stores only the grep of the last $file_na
+me
      }#for loop end
   }#if file_name end
   
for my $key (keys %Hash_filematches) {
  my $value = $Hash_filematches{$key};

   if (scalar @$value) { # check that the arrayref isn't empty
      print "KEY: $key\n";
      print "VALUES: ", join(", ", @$value), "\n\n";
           }
       }
   }

print pp(\%seen_file);
#print pp(\%Hash_filematches);
#print pp(\%Hash_filenames);
__DATA__
file1
file2
file2
file3
[download]

Take it from here and read How di I post a question effectively?

Not certain but may be i should save the data below in an array reference,not in an array??

@{ $Hash_filematches{ $filename } } = grep( /\/\Q$file_name\E#/i
+, @{ $Hash_filenames{ $filename } });
[download]

Not certain but may be i should save the data below in an array reference,not in an array??

You already are

$ perl -MData::Dump::Streamer -e"  $f{f}  = [ grep /\d/ , 1 ..4 ]; Dum
+p( \%f ); "
$HASH1 = { f => [
           1,
           2,
           3,
           4
         ] };

$ perl -MData::Dump::Streamer -e" @{ $f{f} } = grep /\d/ , 1 ..4; Dump
+( \%f ); "
$HASH1 = { f => [
           1,
           2,
           3,
           4
         ] };
[download]

For future reference, as How (Not) To Ask A Question would say, you should clean your room :) write a small program to demonstrate your problem and include sample data :)

The issue is only the data of the last file_name is getting saved.How do I fix it?

Three possibilities

• all the filenames are the same filename (your data is bonkers)
• $filename is empty (your regex is failing)
• something else in your code obliterates $filename or something :)

Try doing this:

my $grepped = grep(...
print $grepped, "\n";
[download]

That will tell you if the data is being overridden or if you're just retrieving the same data each time.

You could also help yourself by tidying up your code (see perlstyle) so you can read it more easily.

Another thing you can do is choose better variable names: using $filename and $file_name is just asking for trouble.

perltidy helps with perlstyle

cleaned up the code a bit.Data is getting overridden for sure