perl 获取匹配行后面的多行

#!/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);