#!/usr/bin/perl
use strict;

my @output;
my $stuff;

if ( <not piped to> and @ARGV == 0 ) {
    print "This is how you use this perl script...\n";
    exit;
}

while (<STDIN>) {
    if ($_ =~ m/start/ ) {
        push @output, chomp;
        $stuff = 1;
    } elsif ( $_ =~ m/end/ ) {
        push @output, chomp;
        changout(@output);
        undef $stuff;
    } elsif ($stuff) {
        push @output, chomp;
    } else {
        print STDOUT $_;
    }
    
}

sub changout
{
    foreach my $line (@_) {
        if ( $line =~ m/something/ ) {
            print STDOUT $line;
        } else {
            print STDOUT $line."\n";
        }
    }
}