--- contrib/check_linux_raid.pl	2007-08-28 04:19:45.000000000 +0100
+++ contrib/check_linux_raid.pl.new	2008-01-21 17:28:18.000000000 +0000
@@ -3,6 +3,7 @@
 # Copyright (c) 2002 ISOMEDIA, Inc.
 # originally written by Steve Milton
 # later updates by sean finney <seanius@seanius.net>
+# bux fixing & usage message by Alain Williams <addw@phcomp.co.uk>
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -26,6 +27,8 @@
 use lib "/usr/local/nagios/libexec";
 use utils qw(%ERRORS);
 
+my ($progname) = $0 =~ m|([^/]+)$|;
+
 # die with an error if we're not on Linux
 if ($^O ne 'linux') {
     print "This plugin only applicable on Linux.\n";
@@ -42,9 +45,22 @@
 	return "UNKNOWN";
 }
 
+sub usage {
+	print "Inspect Linux software raid devices and return a status for nagios\n";
+	print "Usage:\n";
+	print "$progname [--help | -h] [md-device ...]\n";
+	print "A md-device might be: md0\n";
+	print "If md-device is not given, all mds will be inspected\n";
+	exit 0;
+}
+
 my $nextdev;
-if(defined $ARGV[0]) { $nextdev = shift; }
-else { $nextdev = "md[0-9]"; }
+if(defined $ARGV[0]) {
+	$nextdev = shift;
+	usage() if($nextdev eq '--help' or $nextdev eq '-h');
+} else {
+	$nextdev = "md[0-9]+";	# All MD devices
+}
 
 my $code = "UNKNOWN";
 my $msg = "";
@@ -53,6 +69,7 @@
 my %finish;
 my %active;
 my %devices;
+my $debug;
 
 while(defined $nextdev){
 	open (MDSTAT, "< /proc/mdstat") or die "Failed to open /proc/mdstat";
@@ -60,14 +77,22 @@
 	while(<MDSTAT>) {
 		if (defined $device) {
 			if (/(\[[_U]+\])/) {
+				print "status='$1' device '$device'\n" if($debug);
 				$status{$device} = $1;
 			} elsif (/recovery = (.*?)\s/) {  
 				$recovery{$device} = $1;
 				($finish{$device}) = /finish=(.*?min)/;
-			} elsif (/^\s*$/) {
+			} elsif (/^\s*$/) {	# Start of another device - blank line. NB: may not be present
+				print "undef '$device' _='$_'\n" if($debug);
 				$device=undef;
+			} elsif(/^md[0-9]+\s*:/) {	# Start of another device - another way
+				print "undef '$device' _='$_'\n" if($debug);
+				undef $device;
 			}
-		} elsif (/^($nextdev)\s*:/) {
+		}
+
+		# No current device and this line matches the device pattern ?
+		if ( ! defined($device) and /^($nextdev)\s*:/) {
 			$device=$1;
 			$devices{$device}=$device;
 			if (/active/) {