http://blog.livedoor.jp/nipotan/archives/50817627.html

twitter-autofollow.pl

#!/usr/local/bin/perl

use strict;
use warnings;
use Net::Twitter;
use Config::Pit;

my $message = do { local $/; <STDIN> };

my $header = parse_header($message);
exit 0 unless $header->{emailtype} eq 'is_following';
exit 0 unless defined $header->{senderscreenname};

my $config = pit_get("twitter.com", require => {
    consumer_key        => '',
    consumer_secret     => '',
    access_token        => '',
    access_token_secret => '',
});

my $twitter = Net::Twitter->new(
    traits => [qw/API::REST OAuth/],
    %$config,
);

eval { $twitter->create_friend($header->{senderscreenname}) };
if ($@) {
    warn $@;
    exit 0 if $@ =~ /is already on your list/;
}
exit 0;

sub parse_header {
    my $message = shift;
    my %header_data = ();
    while ($message =~ m{^X-Twitter(\w+):\s+(.+)}gm) {
        my $key = $1;
        my $val = $2;
        $header_data{$key} = $val;
    }
    return \%header_data;
}