The classic post on this flip flop subject (now in the tutorial's section) is Flipin good, or a total flop? by Grandfather. Also see the post from ysth in that thread about how to include or exclude the end points (START STOP). I use this every time I write flip/flop code to refresh my recollection.

Update: I personally like Athanasius's code. But here is another way to do it without the flip/flop operator... Here the "state" of inside record or not is handled by being inside the process_record subroutine or not. At some point, you may find this parsing technique of use...I added some junk to the data and moved the START line from the beginning. If you want the junk to be preserved, maybe these are comments? modify the first while loop. Here I deleted ignored it.

#!/usr/bin/perl
use strict;
use warnings;


while (my $line = <DATA>)
{
   process_record($line) if $line =~ /START/;
}

sub process_record
{
   my ($line) = @_;
   my @lines;
   my $found;
   
   push @lines, $line; #the "START" line
   
   while ( $line = <DATA>, $line !~ /END/)
   {
     $found = 1 if $line =~ /def/;
     push @lines, $line;
   }
   push @lines, $line;  #the "END" line
   
   print @lines unless $found;
   return;
}

=prints
    START
xyz
abc
    END
=cut

__DATA__
    START
abc
def
ghi
    END
junk
more junk
    START
xyz
abc
    END
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