If set, and if a Low Threshold is breached, this command will be run. Please enter a valid command.In addition, there are several replacement tags available that can be used to pass information from the Threshold to the script.You can do this as arguments on the command line, or preferably, in the environment of the script.All replacement values will appear in the environment of the script prefixed with THOLD_.So, for example CURRENTVALUE will become THOLD_CURRENTVALUE, and so on.The variables include: <DESCRIPTION> <HOSTNAME> <TIME> <DATE> <URL> <GRAPHID> <CURRENTVALUE> <THRESHOLDNAME> <DSNAME> <SUBJECT> <GRAPH> <HI> <LOW> <DURATION> <TRIGGER> <DETAILS_URL> <DATE_RFC822> <BREACHED_ITEMS>.Finally, Host, Data Query and Data input replacement can be made.For example, if you have a data input custom data called pending, to perform the replacement use |pending|.For Data Query, and Host replacement use Cacti conventions |query_xxxx|, and |host_xxxx| respectively.