}
}

sub read_pingomatic_hosts {
    my $fh = shift;
    my @hosts;
    while(<$fh>) {
	chomp;
	next if /^$/;
	next if /^\s*\#/;
	if (/^\@(.*)\@$/) {
	    no strict 'refs';
	    push @hosts, &{"hostgroup_" . lc($1)};
	} else {
	    push @hosts, pingomatic_host($_);
	}
    }
    @hosts;
}

sub epoch2isodate {
    my $time = shift;
    my @l = gmtime $time;
    sprintf("%04d-%02d-%02dT%02d:%02d:%02dZ",
	    $l[5]+1900, $l[4]+1, $l[3],
	    $l[2],      $l[1],   $l[0]);
}

__END__

=head1 NAME

pingomatic - multiple ping to a number of hosts

=head1 DESCRIPTION

This utility pings to a number of hosts in parallel.

=head2 OPTIONS

=over 4

=item -hosts hostgroup

Use a predefined host group. Predefined host groups are: C<cpan>,
C<freebsd>, C<linux>, and C<search>.

=item -hostfile filename

Use another file with host names instead of the default
C<~/.pingomatic.hosts>.

=item -host hostname

=item -host hostname:port

=item -host hostname:port/protocol

Add the named hostname (optionally with a port in numerical or named
form) to the list of hosts. This option may be specified multiple
times. I<protocol> is also optional and may be something like C<tcp>
or C<icmp>.

=item -ns

Add the locally configured name servers from C</etc/resolv.conf> to
the list of hosts. This is the default, use C<-nons> to remove the
name servers.

=item -d | -debug

Turn debugging on. Debug info is saved to C</tmp/pingomatic.debug>.

=item -interval seconds | -update seconds

Specify an interval in seconds between sending pings. Default is one
second.

=item -log file

Write a tab separated logfile (append if it already exists) with the
per-host and per-interval ping values.

=back

=head2 KEYS

While the script is pinging, the user can use the following keys:

=over 4

=item a

Add interactively another host to the list. To check for a specific
port, use I<host>:I<port>.

=item +

Add one second to the current update interval. The default update
interval is one second.