Quick question about using kill -USR1 to recreate access.log

Maxim Dounin mdounin at mdounin.ru
Tue May 20 11:33:07 UTC 2014


On Mon, May 19, 2014 at 03:06:06PM -0400, samingrassia wrote:

> Thanks to everyone in advance!
> I have a cron that runs the following:
> kill -USR1 `cat $NGINX_PID`
> My questions is during time between the mv and the kill, is there any log
> writes that are being discarded or are they being stacked in memory and
> dumped into the new access.log after it is recreated?

Unless you are trying to move logs to a different filesystem, 
logging will continue to the old file till USR1 is processed.

>From nginx point of view, the "mv" command does nothing - as nginx 
has open file descriptor, it will continue to write to it, and log 
lines will appear in the (old) file - the file which is now have a 
new name.  After USR1 nginx will reopen the log, and will continue 
further logging to a new file.

Maxim Dounin

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