perl 擷取匹配行後面的多行

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

my$flag=0;
my$a;
while(<DATA>)

{
    if(/^>/)
    {
        $flag = 1;
        $a = 0;
    }
    if($flag )
    {
        print $_;
        $a++;
    }
    if($a == 3)
    {
        $flag = 0;
    }
}############!/usr/bin/perl -w
use strict;
open(LOGOUT,">out.log") or die "can't create ";
open(LOGFILE,"ISauditLog_01.log") or die "can not open";#my $line_count = 0;
#while(<LOGFILE>){
#        if(m/dsuser3/){
#               $line_count = 0;
#                print LOGOUT ;
#               $line_count++;
#       }elsif($line_count < 2){
#              print LOGOUT;
#              $line_count++;
#     }#}my $flag=0;while(<LOGFILE>)
{
        if(/dsuser/)
        {
                for($flag=0; $flag <= 1; $flag++)
                {
                        print LOGOUT $_ ;
                        $_ = <LOGFILE>;
                }
        }
}print LOGOUT "end";
close(LOGFILE);
close(LOGOUT);