btool is used to view or validate Splunk config files.
btprobe was meant in the previous answer, which enables you to remove fish bucket information for a specific file.
Easiest way to re-index all inputs on a universal forwarder is to delete the fish bucket index while Splunk UF is stopped:
$SPLUNK_HOME/bin/splunk stop rm -rf $SPLUNK_HOME/var/lib/splunk/fishbucket $SPLUNK_HOME/bin/splunk start
Splunk will re-create the fish bucket index and immediately re-index all the inputs on your universal forwarder, so watch out for your license usage 😉