perl的正则或其他方法匹配每组内容，怎么做

DATE:
[group1]
aaa
bbb
ccc

[group2]
aaa
eee
ccc

[group3]

[group4]
aaa
ccc

perl 的正则 或 其他方法 匹配每组内容，怎么做

#!/usr/bin/env perl

use strict;
use warnings;

while (<DATA>) {
    if (/^(\w)(\1+)$/) {
        print;
    }
}

__DATA__
aaa
bbb
ccc
abc

use Config::Std;

    # Load named config file into specified hash...
    read_config 'demo2.cfg' => my %config;

    # Extract the value of a key/value pair from a specified section...
    $config_value = $config{Section_label}{key};

    # Change (or create) the value of a key/value pair...
    $config{Other_section_label}{other_key} = $new_val;

    # Update the config file from which this hash was loaded...
    write_config %config;

    # Write the config information to another file as well...
    write_config %config, $other_file_name;