Patch to change mythbackend's logfile name

[Bill <billstuff2001@…>]

The attached patch allows one to change the logfile used by a running mythbackend process. It basically allows one to keep mythbackend running for days / weeks / months, and roll the logfile as needed. For example, I have a script that does this at midnight so I get a new log for each day.

This is similar to the functionality in #6190, it works as follows:

mythbackend --setlogfile "log.file.name"

is similar to starting

mythbackend --logfile "log.file.name"

but will signal the currently running mythbackend instance to change it's log file.

[sphery]

It would be significantly simpler to implement functionality for mythbackend similar to #3622 --ideally moving the frontend-only log_rotate() code to a library and reusing it in both applications--and using a real log-rotation application along with a SIGHUP to reopen files. If nothing else, we should have a standard approach in both mythfrontend and mythbackend.

[danielk]

The only proper way to do this is with SIGHUP handling.

[sphery]

Just as an update (thanks to Chris Pinkham for the information), the backend already has the SIGHUP handler, too. So just have send a SIGHUP to reopen log files after rotating.