\d - a digit
\w - a word character
\s - whitespace.

##</code><code>##

foreach my $line ( @lines ) {

  next unless $line =~ m/^\d{6} \w{3}/;
  # Will match '111111 aaa' where 1 is any
  # number, a any char.

  next unless $line =~ m/^\d+\s+\w+/;
  # Will match any number followed by any word.

  # The '^' anchors the search to the beginning
  # of the string.
}