phhttpd can be told to rotate its logs so that existing logs may be processed.
The -r argument to phhttpd_ctl tells phhttpd to rotate its log files. Files will closed, moved to 'filename.N' where N is the next available name, and new logs will be opened as 'filename', where 'filename' is the file= attribute for each file destination.
This is typically used to release the log files from phhttpd's control so that system scripts can compress, archive, or process previous log entries.
While this operation is happening phhttpd assumes it has total control over the logging files being moved. Do not let other programs mess about in the log directories while this operation is taking place, log files could very easily be lost.
The -o argument to phhttpd_ctl tells phhttpd to close the existing file logs and reopen the files with the filenames that were configured. This implies that an external entity has moved the files to new names and wants phhttpd to stop using them.