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

open my $fh, '+>', 'file.log'  or  die $!;
print $fh "Hallo, Welt!\n"  or  die $!;
system('rm -f file.log && touch file.log');
print $fh "Hallo, Welt!\n"  or  die $!;

seek $fh, 0, 0;
print <$fh>;

close $fh;