P:\test>start /b perl -le"open LOG, '>', 'my.log'; 
select LOG; 
$|=1; 
print ~~localtime while sleep 10" 1>nul 2>&1 <nul

P:\test>u:tail -f my.log
Tue Sep 14 12:11:10 2004
Tue Sep 14 12:11:20 2004
^C