#!/usr/bin/perl

use strict;
use warnings;
use FileHandle;

my $log = '/root/Desktop/log.txt';

my $fh1  = FileHandle->new("> $log") or die $!;
print $fh1 "this is a test\n";
$fh1->close;

my $fh2 = FileHandle->new(">> $log") or die $!;
if (defined $fh2) {
    print $fh2 "bar";
    $fh2->close;
}