I'm not sure about the usecase, but if you really care you can use an existing directory (e.g. /) by writing a bit of code to bypass the check for output-dir existence...
By default FIleOutputFormat assumes the output-dir shouldn't exist and will error out during init if it does. You could customize it to not bother to check.
On Mar 2, 2012, at 4:38 PM, Jianhui Zhang wrote:
> Hi all,
> The FileOutputFormat/FileOutputCommitter always treats an output path
> as a directory and write files under it, even if there is only one
> Reducer. Is there any way to configure an OutputFormat to write all
> data into a file?
Arun C. Murthy