#!/usr/bin/perl

use strict;

use Fcntl;

my $TMPDIR = "/tmp";

my $limit = 99999;
my $md;

do { 
    my $tmpname = int(rand($limit));
    $md = "$TMPDIR/runitout_$tmpname";
} until(sysopen(my $fd, $md, O_CREAT|O_EXCL));