Confusing messages from validation of runtime control option:
$ sbin/zabbix_proxy -c ~/ZBX-8391/zabbix_proxy.conf -R log_level_increaseAAA
zabbix_proxy [21649]: unknown log level control option: AAA
$ sbin/zabbix_proxy -c ~/ZBX-8391/zabbix_proxy.conf -R log_level_increase=poller,
zabbix_proxy [21808]: invalid log level control option: process number must be unsigned short non-zero value