find /path/to/directory -name '*.b' -exec rm {} \;


##</code><code>##

use File::Find;
find(sub { $_ =~ /\.b\z/ && unlink $_ }, '/path/to/directory' );


##</code><code>##

---
print map { my ($m)=1<<hex($_)&11?' ':'';
$m.=substr('AHJPacehklnorstu',hex($_),1) }
split //,'2fde0abe76c36c914586c';