#!/usr/bin/perl -T

##
##
## load average monitor
##
## (c)2001 Leo Fellermayr <leosmail@mac.com>
##

##########################################################
# Note: this needs a file, e. g. /var/log/loadavg.log,
#       where the system's load average is written
#       periodically in (probably cron's job? ;-)
#	"uptime" or "w" output is sufficient.
#
# last modification: 11.10.2001, lf
##########################################################

# ----- used modules

use GD;
use Chart::LinesPoints;
use strict;

# ----- global constants

my $logfile = '/var/log/loadavg.log';	# the logfile
my $x_last_values = 20;			# print last 20 values
my $period = 900;			# load average logging steps in sec. = 15 min.

# ----- read load-average values from our $logfile

my @loads = ();

open (LOG, "<$logfile");
my @log = <LOG>;
my @info = stat LOG;
close (LOG);

# reverse order (values are appended onto the eof)
@log = reverse @log;
my $lines = 0;

# format the load average
foreach (@log) {
  chomp $_;
  $_ =~ s/.*://g;
  $_ =~ s/,.*//g;
  $_ =~ s/ //g;
  push @loads, $_;
  $lines++;
  # only as much as needed ($x_last_values)
  last if ($lines eq $x_last_values);
}

# ----- calculate time intervals with unixdate & Co.

my $interval;
my @intervals = ();

# $info[9] contains "file last modified" information,
# so this is the last-update time of our logfile, too.

my $starttime = $info[9];
my @interval_time = ();

# ----- format time like hh:mm

for (my $z = 0; $z < $lines; $z++) {
  $interval = $starttime - $z * $period;
  @interval_time = localtime ($interval);
  $interval = sprintf ("%02d:%02d", $interval_time[2], $interval_time[1]);
  push @intervals, $interval;
}

# ----- prepare image output

my $g = Chart::LinesPoints->new($x_last_values * 40,250);
$g->set ('title' => 'Load-Average auf ' . $ENV{'SERVER_NAME'});
$g->set('x_label' => "Uhrzeit");
$g->set('y_label' => "Load");
$g->set('grid_lines' => "true");
$g->set('colors' => [[0,153,0]]);
$g->set('legend' => "false");
$g->add_dataset(@intervals);
$g->add_dataset(@loads);

# ----- output image

$g->cgi_gif();