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use POSIX       qw( strftime );
use Time::Local qw( timegm );
...
print(strftime("%Y_%m_%d\n", 
   gmtime(timegm(0,0,0,$d,$m,$y) - 24*60*60)
));

use POSIX       qw( strftime );
use Time::Local qw( timegm );
...
($d,$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));