Scan for new files in a directory. The first argument is a directory to scan. The second argument is optional, and it is a directory to copy any newly added files to. This is for debugging a running program.

scan_folder.pl

#!/usr/bin/perl

use strict;
use warnings;
use File::Copy;

my $dir_to_scan = $ARGV[0];
my $dir_to_save = $ARGV[1];

if($dir_to_scan !~ /\/$/) { $dir_to_scan .= '/'; }
if($dir_to_save !~ /\/$/) { $dir_to_save .= '/'; } 

my %found_files = ();
print "scanning dir for changes: " . $ARGV[0] . "\n";
while(1) {
  opendir(DIR, $dir_to_scan) or die $!;
  while(my $file = readdir(DIR)) {
    my $full_file_path = $dir_to_scan .  $file;
    if($file !~ /^\./ and not defined($found_files{$file})) {
      $found_files{$file} = 1;
      print $file . "\n";
      if(defined($dir_to_save)) {
        print "Saving $full_file_path to $full_path_for_save\n";
        copy($full_file_path, $dir_to_save) or die "Copy failed:  $!";
      }
    }
  }
  closedir(DIR);
}