my $logfile=$PWD.$Thismachineaddr.".log";
open(LOGF, ">$logfile");
...
open STDIN, '/dev/null'   or die "ERROR: Can't read /dev/null: $!";
open STDOUT, '>>/dev/null' or die "ERROR: Can't write to /dev/null: $!";
open STDERR, '>>/dev/null' or die "ERROR: Can't write to /dev/null: $!";