I have not tried this, but per docs.Splunk:
Set
DATETIME_CONFIG = NONEto prevent the timestamp processor from running. When timestamp processing is off, Splunk Enterprise does not look at the text of the event for the timestamp and instead uses the event time of receipt, the time the event arrives through its input. For file-based inputs, the event timestamp is taken from from the modification time of the input file.
Set
DATETIME_CONFIG = CURRENTto assign the current system time to each event as Splunk Enterprise indexes it.
from User warren – Stack Overflow https://stackoverflow.com/questions/75551129/when-loading-a-csv-via-the-ui-is-it-possible-to-use-the-filename-to-obtain-the/75551665#75551665
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