#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11147822
use warnings;

my @files = map "/tmp/11147822.$_.txt", 1 .. 100; # FIXME
my $outpath = "/tmp/11147822.outpath"; # FIXME

open my $fh, '-|', "sort @files" or die;
open my $tosort, '|-', "sort -n -k2 >$outpath" or die;
<$fh> =~ /^(\w+)\s+(\d+)/ or die;
my ($name, $value) = ($1, $2);
while( <$fh> )
  {
  if( /^(\w+)\s+(\d+)/ )
    {
    if( $1 eq $name ) { $value += $2; }
    else
      {
      print $tosort "$name\t$value\n";
      ($name, $value) = ($1, $2);
      }
    }
  }
print $tosort "$name\t$value\n"; # be sure to print last one
close $tosort or die;