Hi, I modified your code to use threads, and I used numbers1..4 as the filenames, which I filled with

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

my $file = shift or die;

open (FH,">$file") or die;

for(1..1000){
 my $first = sprintf('%03d', int rand 999);
 my $second = sprintf('%03d', int rand 999);
 my $third = sprintf('%04d', int rand 9999);
 print FH  "$first-$second-$third\n";
}
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for testing.

Now here is a way to search them for a single number, which stops all the threads when a number is found and reports the line number. Your Tk code could use some minor fixing, but that is up to you. There is also alot of code cleanup and opportunities for ingenious juggling of the return data....like search certain threads only for certain prefixes, or looking for the same number on multiple lists. But I made this as simple as I could to demonstrate the basics... like the timer to watch the shared variables, and how to cleanup the threads when exiting. Also you will need to work out proper messaging and resetting the threads after an empty search

#!/usr/bin/perl
use warnings;
use strict;
use Tk;
use Tk::Dialog;
use threads;
use threads::shared;


my @sfiles = qw(numbers1 numbers2 numbers3 numbers4);

# make threads first before any tk code
my %shash;
my %thash;
my $numworkers = scalar @sfiles;
my $searchnum;
share $searchnum; 
$searchnum = '002-339-7473';

foreach my $dthread(1..$numworkers){
 share ($shash{$dthread}{'go'});
 share ($shash{$dthread}{'die'});
 share ($shash{$dthread}{'file'});
 share ($shash{$dthread}{'return'});

   
 $shash{$dthread}{'go'} = 0;
 $shash{$dthread}{'file'} = shift @sfiles;
 $shash{$dthread}{'die'} = 0;
 $shash{$dthread}{'return'} = '';
 
 $thash{$dthread}{'thread'} = threads->new(\&work,$dthread);
}



my $count = 1;

my $mw = MainWindow->new;

my $c = $mw->Canvas(
    -width =>400,
    -height=>200,
    -background => "white");
$c->pack;
############################Main window
my $quit = $mw->Button(
        -text        => "Quit",
        -padx        => "8",
        -command    => \&Quit);
$quit->place(-x => 350, -y => 180);
###########################adds the quit button

my $Find = $mw->Button(
        -text        => "Search",
        -command    => \&Search);
$Find->place(-x => 300, -y => 180);
################################################

my $lab = $mw->Label (
        -text    =>    "Enter Phone Number",
        -background => "white"
        );
$lab->place(-x => 5, -y => 50);
##############################Label

my $Entry = $mw->Entry(
        -textvariable    =>    \$searchnum,
        -background        =>    "white"
        );
$Entry->place(-x => 5, -y => 68);

##################################Entry

my $text = $mw->Text(
        -height        => 5,
        -width        => 55,
        -wrap        => 'char'
        );
$text->place(-x => 5, -y => 90);

#################################

my $labWarning = $mw->Label (
        -text    =>    'Example XXX - XXX - XXXX',
        -background => "white"
        );
$labWarning->place(-x => 140, -y => 68);

my $index = 1;
 



#######################################

sub Quit {

    my $d = $mw->Dialog(
        -text        => "Are you sure you want to quit?",
        -buttons    => ["Yes", "No"]);
    my $answer = $d->Show();

    close(UNLOCK);

    #cleanup threads
    if($answer eq "Yes"){
        for(1..$numworkers){
           $shash{$_}{'die'} = 1;
       $thash{$_}{'thread'}->join;
          }
    exit;
    }  

}

sub Search {

my $found = 0;

for(1..$numworkers){
    $shash{$_}{'go'} = 1;
  }

  #setup a timer to watch for returns thru shared variables
 my $timer; # declare outside of block so you can kill it in callback
 $timer = $mw->repeat(10,sub{
                            
                for(1..$numworkers){
        
            if( length $shash{$_}{'return'} > 0){
                  
                 if( $shash{$_}{'return'} > 0  ){
                    my $message = "thread  $_ detected number at line 
+$shash{$_}{'return'} \n";
                    print "$message\n";
                $text->insert('end',"$message\n");
              }
              #stop other threads
                      for(1..$numworkers){ $shash{$_}{'return'} = 0 }
                  #stop timer
              $timer->cancel;
            }
            }
                });


}

MainLoop;    

######################################################################
+#
sub work{
  my $dthread = shift;
    $|++; 
    
    my $file = $shash{$dthread}{'file'};
    open(FH,"< $file") or die "$!\n";
    print "thread $dthread created\n";
    
    while(1){
       if($shash{$dthread}{'die'} == 1){ goto END }; 
      
             if ( $shash{$dthread}{'go'} == 1 ){
                     seek FH, 0, 0;  #reset to top
                     $shash{$dthread}{'return'} = '';
             print "thread $dthread going\n";
               while(my $line = <FH>){
                  chomp $line;
              
              if($line eq $searchnum){   
                     $shash{$dthread}{'return'} = __LINE__ ;
                     print "$dthread found $shash{$dthread}{'return'}\
+n";
                 goto RESET;
                   }
                    
                         if($shash{$dthread}{'go'} == 0){goto RESET}
                         if($shash{$dthread}{'die'} == 1){ goto END };
+ 
                        }
             RESET:
             $shash{$dthread}{'go'} = 0; #turn off self before returni
+ng      
             print "thread $dthread going back to sleep\n";
       }else
         { select(undef,undef,undef,.1) } # tenth second sleep, can be
+ smaller
    }
END:
}
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