How to create a debug log#

Creating a debug log is actually quite simple. You just have to add a few lines to the configuration file.

Regular debug output#

Add the following right at the beginning of the rsyslog.conf file. This will ensure that debug support is the first thing to enable when the rsyslog service is started:

$DebugFile /var/log/rsyslog.debug
$DebugLevel 2

The actual file path and name may be changed if required.

Having set the above, when rsyslog is restarted it will produce a continuous debug file.

Debug on Demand#

For having rsyslog be ready to create a debug log (aka Debug on Demand), the settings are a little different.

$DebugFile /var/log/rsyslog.debug
$DebugLevel 1

Now, rsyslog will not create a debug log on restart, but wait for a USR signal to the pid. When sent, the debug output will be triggered. When sent again, debug output will be stopped.

kill -USR1 `cat /var/run/rsyslogd.pid`

Notes#

Having debug output enabled, the debug file will grow very quickly. Make sure to not have it enabled permanently. The file will eventually fill up the disk.
Debug mode is not to be used in a productive environment as a permanent setting. It will affect the processing and performance.

How to create a debug log#

Regular debug output#

Debug on Demand#

Notes#

See Also#