diff --git a/checks/check_hddtemp.sh b/checks/check_hddtemp.sh
index 424d829..b73ff40 100755
--- a/checks/check_hddtemp.sh
+++ b/checks/check_hddtemp.sh
@@ -11,9 +11,18 @@
 #	- deliver performance data
 #	- options in linux style
 #	- it should do its job perfectly
+#	- switchable from celsius to fahrenheit
 #
 # The warning and critical values are from a 2007 Google study (Failure Trends in a Large Disk Drive Population)
 #
+#
+# USAGE:
+# ./check_hddtemp.sh -d <device> -w <warn> -c <crit>
+# Nagios script to get the temperatue of HDD from hddtemp
+#
+# If you may have to let nagios run this script as root
+# This is how the sudoers file looks in my debian system:
+# nagios  ALL=(root) NOPASSWD:/<path>/<to>/check_hddtemp.sh
 ################################################################################
 
 HDDTEMP="$(type -P hddtemp)"