use File::Find;

$source = '/somedir';
$somefile = 'somefile.txt';

traverse();

sub traverse {
    my %opts = (  wanted       =>    \&eval_files,
    );

    finddepth(\%opts, $source);
}

sub eval_files {
      if (-f && $_ eq $somefile) {
          print 'Got ', $_,"\n";
      }
}