External Commands Reference - REMOVE_HOST_ACKNOWLEDGEMENT
REMOVE_HOST_ACKNOWLEDGEMENT;host_name
This removes the problem acknowledgement for a particular host. Once the acknowledgement has been removed, notifications can once again be sent out for the given host.
#!/bin/sh
# This is a sample shell script showing how you can submit the REMOVE_HOST_ACKNOWLEDGEMENT command
# to Naemon. Adjust variables to fit your environment as necessary.
printf "[%lu] REMOVE_HOST_ACKNOWLEDGEMENT;host1\n" `date +%s` > /var/lib/naemon/naemon.cmd