/var/log/messages
logger hello

/etc/rsyslog.conf
 - Faciliy
 - Priority
 - Destination
-/var/log/maillog #hyphen to say buffer before write on disk. More efficient

ErrorLog syslog:local1
local1.error    /var/log/httpd-error.log

echo "*.debug /var/log/messages-debug" > /etc/rsyslog.d/debug.conf
logger -p daemon.debug "Daemon Debug Message"

echo "authpriv.alert /var/log/auth-errors.conf" > etc/rsyslog.d/auth-errors.conf
man rsyslog.conf Selector > Facility/Priority pour obtenir la liste.
logger -p authpriv.alert "Test authpriv.alert"