use strict; use warnings; OUTER: while (my $line = ) { my @words = split /\s+/, $line; for (@words) { next OUTER unless /^0{7}\d$/; } print $line; } __DATA__ 00000000 00000001 00000009 00000006 FFFFFFFF 00000007 6C163512 00000000 00000008 00000003 00000004 01020102