log_monitor/config/logfiles.config

{monitored_logs, [
    {
        {group, "Test"},
        {email_receivers, ["user@example.com"]},
        {email_subject, "[%F] Error notification"},
        {default_error_regex, "Error"},
        {logfiles, [
            {
                {file, "/tmp/lines.log"},
                {error_regex, "ERROR"}
            }
        ]}
    }
]}.