use Proc::Background;

my @commands = (
  ['./Files1.exe ALL'],
  ['./Files2.exe ALL'],
  ['./Files3.exe ALL'],
  ['./Files4.exe ALL'],
);

my @procs = map {  Proc::Background->new(@$_) } @commands;

$_->wait for @procs;

system 'echo', 'CSCProc', '--pidsAndExitStatus', map { $_->pid, $_->wait } @procs;

`mergefiles.exe`;

my @scripts = qw(... commands ...);
my @jobs = ();
foreach my $script (@scripts) {
  my $job = threads->create( sub {
    system($script);
  });
  push @jobs, $job;
}

$_->join() foreach @jobs;

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

my @scripts = (
  q(echo "script 1 reporting"),
  q(perl -e "sleep 2; print qq{hi there! This is script 2 reportingn}"),
  q(echo "script 3 reporting"),
);

my @jobs = map {
  threads->create(sub{
    system($_);
  });
} @scripts;

$_->join foreach @jobs;

print "finished all my jobsn";

system q(echo "This is the last job");

C:...>perl stackoverflow.pl

"script 1 reporting"
"script 3 reporting"
hi there! This is script 2 reporting
finished all my jobs
"This is the last job"