Try hitting this url:
https://yoursplunkhost:8089/services/admin/inputstatus/TailingProcessor%3AFileStatus
This only works if you changed the admin password on the Splunk instance/universal forwarder.
Otherwise you can run this command on the host:
./splunk _internal call /services/admin/inputstatus/TailingProcessor:FileStatus
Try hitting this url:
https://yoursplunkhost:8089/services/admin/inputstatus/TailingProcessor%3AFileStatus
This only works if you changed the admin password on the Splunk instance/universal forwarder.
Otherwise you can run this command on the host:
./splunk _internal call /services/admin/inputstatus/TailingProcessor:FileStatus
This is a great question, if only it had an answer. Oh wait?