[mythtv-users] Rotating log files (was Re: --logfile vs. --logpath)

[Craig Treleaven]

At 12:24 PM -0400 5/18/12, Michael T. Dean wrote:
>On 05/18/2012 07:59 AM, Craig Treleaven wrote:
>>At 5:10 PM -0400 5/17/12, Michael T. Dean wrote:
>>>On 05/17/2012 03:23 PM, Richard Shaw wrote:
>>>>On Thu, May 17, 2012 at 2:08 PM, Raymond Wagner wrote:
>>>>>On 5/17/2012 14:06, Stephan Seitz wrote:
>>>>>>I'm really wondering who thought the change from logfile to logpath was
>>>>>>a good idea. While you now have logfiles according to the name of
>>>>>>process (e.g. mythbackend or mythpreviewgen), the names contain
>>>>>>"cryptic" things like PID and date. How can you now configure any
>>>>>>logrotation program to rotate the right logfiles?
>>>>>
>>>>>Wildcards and manual postrotate definitions.
>>>>>
>>>>>http://www.mythtv.org/wiki/Logrotate_-_mythfrontend
>>>>>http://www.mythtv.org/wiki/Logrotate_-_mythbackend
>>>>What I'd really like to see is a sane logrotate config for 
>>>>mythpreviewgen... :)
>>>
>>>http://www.mythtv.org/wiki/Category:Log_Rotation_Configuration_Files
>>>
>>
>>I've been doing some testing with 0.25 so I've never had the 
>>backend running more than a few hours at a time. Correct me if I'm 
>>wrong, but for mythpreviewgen, (and mythcommflag, and 
>>mythfilldatabase, I think) the key is the following lines:
>>lastaction
>>find /var/log/mythtv/old -name 'mythpreviewgen*' -type f -mtime +30 -delete
>>Each time one of these guys run, they create a new log file.
>
>If you're using --logpath file logging, then, yes. If you're using 
>syslog logging, and you've configured it to always write to a single 
>file, then each time any mythpreviewgen instance is run, it will 
>stick all its log output into that file (say, 
>/var/log/mythtv/mythpreviewgen.log)--along with all the other 
>mythpreviewgen instances' log output, including the 4 other 
>instances of mythpreviewgen that are running at the exact same time 
>(resulting in each line of the log file showing output from 
>different mythpreviewgen runs, making a very confusing mess :).
>
>>These logs don't need to be "rotated"--just pruned periodically. Right?
>
>Right. Currently, we have the command set to keep the file for 30 
>days (and I plan to add text, eventually, to the pages that describe 
>the various "configurable" options, such as this), primarily just to 
>keep it the same as the mythbackend/mythfrontend "rotate" periods. 
>However, if someone beats me to documenting some of these things, I 
>won't complain... ;)
>
>Note that the --syslog configuration keeps only the last 9 days 
>worth of mythpreviewgen.log (primarily through the fact that it 
>keeps 8 "old" rotated versions, and it runs daily.
>
>>I think I'm going to add that to my daily db backup and 
>>optimization. For me, I think 7 days of previewgens and commflags 
>>would be *lots*. Maybe 14 days of mfd.
>
>You're not running logrotate for other things, already? If not, you 
>may want to consider it. (It or Rot[t]log, which I run, but I 
>haven't posted any config files for it, yet, since I seem to be only 
>one of 3 people actually using it.) MythTV can't be the only thing 
>on your system writing out log messages...

Thanks, Mike.  I'm running on OS X and it uses newsyslog :
https://developer.apple.com/library/mac/#documentation/Darwin/Reference/Manpages/man8/newsyslog.8.html

Apparently*, I can put a configuration file in in /etc/newsyslog.d/ 
to control Myth's log rotation.  It doesn't allow for the find ... 
-delete command, though.  But it wouldn't be a big deal to add that 
to the daily myth script.

I could install logrotate.  I might, too.  The newsyslog config files 
are a bit weird.  Apple used plist files for tonnes of other configs, 
but not this.  ;)

>>Does the backend and frontend continue to write to the same log 
>>file for as long as they are running--potentially weeks or months?
>
>Yes--or, technically, they write to the same log file name for as 
>long as the instance runs. If you send a hangup signal, they will 
>close and reopen the log files, so you can move the old file and 
>then have it create a new (same-named) file (which will be a 
>different file, since you've moved the old file to a different 
>name). See the "After rotating..." section at 
>http://www.mythtv.org/wiki/Category:Log_Rotation_Configuration_Files 
>.
>

Good.

Craig
* I never got around to doing this with Myth .20 through .24!  A 
couple times a year, I'd move the backend log around by hand.  Good 
thing disk space is cheap!!