$file_name =~ s/.*[\/\\](.*)/$1/;

##</code><code>##

open(SAVEPDB,">$directory/${file_name}_${md5file}")
             or die $!;
##</code><code>##

if($file_name =~ /(\w+\.?\w+)$/) {
   $file_name = $1;
} else {
   die "invalid and possibly dangerous characters in filename."
}