tailf.pl

use strict;
use warnings;


use AnyEvent;
use AnyEvent::Handle;

# 引数に指定したファイルすべてに対して tail -f する
# busy loop になっていてCPUを食う

$| = 1;

my $cv = AnyEvent->condvar;

my @files = @ARGV;
my %handles;
sub create_handle {
    my ($key, $fh) = @_;
    $handles{$key} = AnyEvent::Handle->new(
        fh => $fh,
        on_error => sub {
            my ($hdl, $fatal, $msg) = @_;
            warn "got error $msg\n";
            $hdl->destroy;
            $cv->send;
        },
        on_eof => sub {
            my $hdl = shift;
            $hdl->destroy;
            create_handle($key, $fh); # loop
        },
        on_read => sub {
            my $hdl = shift;
            $hdl->push_read(line => sub {
                my ($hdl, $line) = @_;
                print "$line\n";
            })
        },
    );
}
my @fhs;
for my $file (@files) {
    open my $fh, '<', $file;
    push @fhs, $fh;
    create_handle($file, $fh);
}

my $int; $int = AnyEvent->signal(
    signal => 'INT',
    cb => sub {
        for my $fh (@fhs) {
            close $fh;
        }
        undef %handles;
        undef $int;
        $cv->send;
    }
);

$cv->recv;