Let's call the file with the interesting categories imei_tags.txt and the file with 3 million devices imeis.txt then something like the following would do the job...
WARNING: Untested off the top of my head code 
#! /usr/bin/perl

use strict;
use warnings;

open (my $imeitag , '<', '/path/to/imei_tags.txt');
my %devices;
while(<$imeitag>){
  $devices{$1}=0 if /^\s*(\d{8}$/;
}

close $imeitag;

open (my $imei, '<', '/path/to/imeis.txt');
while(<$imei>){
  my $imeitag=$1 if /^\s*(\d{8}\d+\s*$/
  $devices{$imeitag}++ if defined $devices{$imeitag};
}

close $imei;

my $count=0;
for my $imeitag (sort {$devices{$a}<=>$devices{$b}} keys %devices){
  print "$imeitag\n";
  $count++;
  last if $count >=100;
}

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In reply to Re: Perl text processing by Utilitarian
in thread Perl text processing by biboshakan

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