syslog-ng 系列连载-45 ：参考-日志路径

8.3. Log path flags

Flags influence the behavior of syslog-ng, and the way it processes messages. The following flags may be used in the log paths, as described in .

# 注释 ：flags 用于控制 syslog-ng 的行为，只能用于 log 语句内。

Flag	Description
final	This flag means that the processing of log statements ends here. Note that this does not necessarily mean that matching messages will be stored only once, as there can be matching log statements processed prior the current one.   # 注释 ：final 表示对该日志的处理结束，但不表示消息只被存储1次，因为之前可能有匹配过的了
fallback	This flag makes a log statement 'fallback'. Fallback log statements process messages that were not processed by other, 'non-fallback' log statements.   # 注释 ：fallback 表示该 log 语句是一个 fallback ，如果消息不匹配任何其他 log 语句，则一律发送到这里来；换句话说，就是最后的选择
catchall	This flag means that the source of the message is ignored, only the filters are taken into account when matching messages. A log statement using the catchall flag processes every message that arrives to any of the defined sources.   # 注释 ：catchall 表示忽略任何消息的 source ，只考虑 filters 部分。
flow-control	Enables flow-control to the log path, meaning that syslog-ng will stop reading messages from the sources of this log statement if the destinations are not able to process the messages at the required speed. If disabled, syslog-ng will drop messages if the destination queues are full. If enabled, syslog-ng will only drop messages if the destination queues/window sizes are improperly sized.   # 注释 ：flow-control 表示允许对该 log path 进行流控。如果 destination 暂时无法接收数据，则停止读取 souce 的消息。   # 如果禁用的话，syslog-ng 会在目标队列满的时候丢弃 source 来的消息；如果启用的话，只有在目标队列/窗口大小的大小不正确时才丢弃消息

Table 8.12. Log statement flags

	Example 8.16. Using log path flags

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