This is an example from the following section of the documentation.
Send all events from a data input to a specific index
To send all events from a particular data input to a specific index, add the following line to the input's stanza in inputs.conf on <strike> the Splunk Enterprise component where the data is entering the system:</strike> either the indexer itself or a forwarder sending data to the indexer:
index = <index_name>
The following example inputs.conf stanza sends all data from /var/log to an index named fflanda:
disabled = false
index = fflanda