use POSIX       qw( strftime );
use Time::Local qw( timegm );

my ($d,$m,$y) = (localtime())[3,4,5];

print(strftime("%Y_%m_%d\n", 
   gmtime(timegm(0,0,0,$d,$m,$y) - 24*60*60)
));

##</code><code>##

use POSIX       qw( strftime );
use Time::Local qw( timegm );

my ($sec,$min,$hour,$d,$m,$y) = localtime();
($d,$m,$y) = (gmtime(timegm(0,0,0,$d,$m,$y) - 24*60*60))[3,4,5];

print(strftime("%Y_%m_%d_%H_%M_%S\n", $sec,$min,$hour,$d,$m,$y));