I have events from an application containing various logger type messages, I.e: INFO, WARN, ERROR... Searching just for the string 'ERROR' returns false positives as some INFO messages contain a matching string pertaining to error detection and such... How do I match these events similar to 'grep ^ERROR '?
You could extract the log level in a field (if it isn't being done automatically). You could use the Interactive Field Extractor for this, or specify your own props/transforms. Having done so, you could search for log_level = INFO|WARN|ERROR.
For version 6.4.0 -> Settings -> Fields -> Field Extractions -> Open Field Extractor
You can also search for the events, click on the left most row expansion button, and select "Extract Fields" from the "Event Actions" menu.