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https://issues.apache.org/jira/browse/FLUME-1400?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13424255#comment-13424255
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Jarek Jarcec Cecho commented on FLUME-1400:
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That someone was probably me. Small "f" (-f) will just follow one file - e.g.
if someone will rotate the file, tail will still remain tailing original
(moved) file. Big "f" (-F) will detect file move or rotation and will start
tailing the new file (with name as was specified on the command line). Does
that make sense or should I put together some examples?
Jarcec
> Understand and document behavior of exec source when tailing rolling logs
> -------------------------------------------------------------------------
>
> Key: FLUME-1400
> URL: https://issues.apache.org/jira/browse/FLUME-1400
> Project: Flume
> Issue Type: Improvement
> Reporter: Patrick Wendell
> Assignee: Patrick Wendell
>
> There has been some discussion recently around the behavior of exec("tail
> -f") when tailing logs, if the log files are themselves being rolled and
> renamed by a writer process.
> The primary concern is whether there is a race condition or correctness
> problem related to tailing a log which is renamed.
> I am fairly certain that the tail binary, when passed -f, will deal with all
> of the ugliness of recognizing when a file is rolled and open the new
> "current" file as expected. However, we should both verify and document that
> behavior.
> Flume OG, which implemented its own tailing functionality, dealt with this
> ugliness by introducing increasing break-fix complexity to the tail source. I
> am hoping that by delegating to the "tail" binary we have avoided having to
> do this (though at the cost of OS portability). Nonetheless, I should confirm
> this.
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