Log4j2的RollingFileAppender详解

喜欢ヅ旅行 2024-03-24 13:33 33阅读 0赞

> 官方配置文档：[https://logging.apache.org/log4j/2.x/manual/filters.html][https_logging.apache.org_log4j_2.x_manual_filters.html]

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## 1. 背景介绍 ##

### 1.1 `<Appenders>` ###

An appender is configured either using `the specific appender plugin's name` or with `an appender element` and `the type attribute` containing the appender plugin’s `name`.

In addition each appender `must have a name` attribute specified with a value that `is unique` within the set of appenders. The name will be used by loggers to `reference the appender` as described in the previous section.

--------------------

### 1.2 RollingFileAppender：实现日志文件自动更新 ###

当满足条件（日志大小、指定时间等）重命名或打包原日志文件进行归档，生成新日志文件用于日志写入。

The `RollingFileAppender` is an `OutputStreamAppender` that `writes to the File` named in the `fileName parameter` and rolls the file over according the `TriggeringPolicy` and the `RolloverPolicy`.

--------------------

## 2. RollingFileAppender Parameters ##

<table> 
 <thead> 
  <tr> 
   <th align="left">Parameter Name</th> 
   <th align="left">Type</th> 
   <th align="left">Description</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td align="left">append</td> 
   <td align="left">boolean</td> 
   <td align="left">When true - the default, records will be appended to the end of the file. When set to false, the file will be cleared before new records are written.</td> 
  </tr> 
  <tr> 
   <td align="left">bufferedIO</td> 
   <td align="left">boolean</td> 
   <td align="left">When true - the default, records will be written to a buffer and the data will be written to disk when the buffer is full or, if immediateFlush is set, when the record is written. File locking cannot be used with bufferedIO. Performance tests have shown that using buffered I/O significantly improves performance, even if immediateFlush is enabled.</td> 
  </tr> 
  <tr> 
   <td align="left">bufferSize</td> 
   <td align="left">int</td> 
   <td align="left">When bufferedIO is true, this is the buffer size, the default is 8192 bytes.</td> 
  </tr> 
  <tr> 
   <td align="left"><code>createOnDemand</code></td> 
   <td align="left">boolean</td> 
   <td align="left">The appender creates the file on-demand. The appender only creates the file when a log event <code>passes all filters</code> and <code>is routed to this appender</code>. Defaults to false.<br>createOnDemand 解决重启tomcat或者java -jar 重新运行应用程序时数据丢失的问题（参考别人还不理解）</td> 
  </tr> 
  <tr> 
   <td align="left">filter</td> 
   <td align="left">Filter</td> 
   <td align="left">A Filter to determine if the event should be handled by this Appender. More than one Filter may be used by using a CompositeFilter.</td> 
  </tr> 
  <tr> 
   <td align="left"><code>fileName</code></td> 
   <td align="left">String</td> 
   <td align="left"><code>The name of the file to write to</code>. If the file, or any of its parent directories, do not exist, they will be created.</td> 
  </tr> 
  <tr> 
   <td align="left"><code>filePattern</code></td> 
   <td align="left">String</td> 
   <td align="left"><code>The pattern of the file name of the archived log file</code>. The format of the pattern is dependent on the RolloverPolicy that is used. The DefaultRolloverPolicy will accept both a date/time pattern compatible with <a href="https://download.oracle.com/javase/7/docs/api/java/text/SimpleDateFormat.html" rel="nofollow">SimpleDateFormat</a> and/or a <code>%i</code> which represents an integer counter. The pattern also supports interpolation at runtime so any of the Lookups (such as the <a href="https://logging.apache.org/log4j/2.x/manual/lookups.html#DateLookup" rel="nofollow">DateLookup</a>) can be included in the pattern.</td> 
  </tr> 
  <tr> 
   <td align="left">immediateFlush</td> 
   <td align="left">boolean</td> 
   <td align="left">When set to true - the default, each write will be followed by a flush. This will guarantee that the data is passed to the operating system for writing; it does not guarantee that the data is actually written to a physical device such as a disk drive.Note that if this flag is set to false, and the logging activity is sparse, there may be an indefinite delay in the data eventually making it to the operating system, because it is held up in a buffer. This can cause surprising effects such as the logs not appearing in the tail output of a file immediately after writing to the log.Flushing after every write is only useful when using this appender with synchronous loggers. Asynchronous loggers and appenders will automatically flush at the end of a batch of events, even if immediateFlush is set to false. This also guarantees the data is passed to the operating system but is more efficient.</td> 
  </tr> 
  <tr> 
   <td align="left">layout</td> 
   <td align="left">Layout</td> 
   <td align="left">The Layout to use to format the LogEvent. If no layout is supplied the default pattern layout of “%m%n” will be used.</td> 
  </tr> 
  <tr> 
   <td align="left"><code>name</code></td> 
   <td align="left">String</td> 
   <td align="left">The <code>name</code> of the Appender.</td> 
  </tr> 
  <tr> 
   <td align="left"><code>policy</code></td> 
   <td align="left">TriggeringPolicy</td> 
   <td align="left"><code>The policy to use to determine</code> if a rollover should occur.</td> 
  </tr> 
  <tr> 
   <td align="left">strategy</td> 
   <td align="left">RolloverStrategy</td> 
   <td align="left">The strategy to use to determine the name and location of the archive file.</td> 
  </tr> 
  <tr> 
   <td align="left">ignoreExceptions</td> 
   <td align="left">boolean</td> 
   <td align="left">The default is <code>true</code>, causing exceptions encountered while appending events to be internally logged and then ignored. When set to <code>false</code> exceptions will be propagated to the caller, instead. You must set this to <code>false</code> when wrapping this Appender in a <a href="https://logging.apache.org/log4j/2.x/manual/appenders.html#FailoverAppender" rel="nofollow">FailoverAppender</a>.</td> 
  </tr> 
  <tr> 
   <td align="left">filePermissions</td> 
   <td align="left">String</td> 
   <td align="left">File attribute permissions in POSIX format to apply whenever the file is created.Underlying files system shall support <a href="https://docs.oracle.com/javase/7/docs/api/java/nio/file/attribute/PosixFileAttributeView.html" rel="nofollow">POSIX</a> file attribute view.Examples: rw------- or rw-rw-rw- etc…</td> 
  </tr> 
 </tbody> 
</table>

--------------------

## 3. `<Policies>` ##

### 3.1 （1）SizeBased Triggering Policy：基于文件大小的滚动策略 ###

The `SizeBasedTriggeringPolicy` causes a rollover `once the file has reached the specified size`. The size can `be specified in bytes`, with the suffix KB, MB, GB, or TB, for example `20MB`. The size may also contain a fractional value such as `1.5 MB`. The size is evaluated using the Java root Locale so a period `must` always be used for the fractional unit.

When combined with a `time based triggering policy` the file pattern must contain a `%i` otherwise the target file `will be overwritten` on every rollover as the `SizeBased Triggering Policy` will not cause `the timestamp value` in the file name to change. When used without a time based triggering policy the `SizeBased Triggering Policy` will cause the timestamp value to change.

--------------------

#### 验证1： `<SizeBasedTriggeringPolicy size="1KB"/>` ####

<?xml version="1.0" encoding="UTF-8"?>
    <configuration status="info" monitorInterval="10">
    
        <properties>
            <property name="LOG_HOME">./applog/logs</property>
            <Property name="FILE_NAME" value="practisesvr"/>
            <Property name="LOG_PATTERN" value="[%d{yyyy-MM-dd HH:mm:ss}] [%-5level] [%thread] [%file:%line] → [%enc{%m}{CRLF}]%n"/>
        </properties>
    
        <appenders>
            <RollingFile name="SIZE_BASED_TRIGGERING"
                         fileName="${LOG_HOME}/${FILE_NAME}.log"
                         filePattern="${LOG_HOME}/${FILE_NAME}_%d{yyyy-MM-dd}_%i.log.gz" createOnDemand="true">
                <ThresholdFilter level="info" onMatch="ACCEPT" onMismatch="DENY"/>
                <PatternLayout pattern="${LOG_PATTERN}"/>
                <Policies>
                    <SizeBasedTriggeringPolicy size="1KB"/>
                </Policies>
                <DefaultRolloverStrategy max="5"/>
            </RollingFile>
        </appenders>
    
        <loggers>
            <root level="all">
                <AppenderRef ref="SIZE_BASED_TRIGGERING"/>
            </root>
        </loggers>
    </configuration>

上述模板中

*  日志先写入`practisesvr.log`中，每当文件大小达到`1KB`时，按照在`./applog/logs`目录下以`practisesvr_2023-04->02_1.log.gz`格式对该日志进行`压缩重命名并归档`，并生成新的文件`practisesvr.log`进行日志写入。
 *  `filePattern`属性的文件格式中`%i`就类似于一个整数计数器，受到`<DefaultRolloverStrategy max="5"/>`控制，当文件个数达到`5个`的时候会`循环覆盖`前面已归档的1-5个文件。若不设置该参数，默认为`7`。  
    ![在这里插入图片描述][79932046f0ee4b36911f4630d6def253.png]

--------------------

### 3.2 （2）TimeBased Triggering Policy：基于时间间隔的滚动策略 ###

The `TimeBasedTriggeringPolicy` causes a rollover once `the date/time pattern no longer applies to the active file`. This policy accepts an `interval` attribute which indicates `how frequently` the rollover should occur based on the time pattern and a `modulate` boolean attribute.

--------------------

**TimeBasedTriggeringPolicy Parameters**

<table> 
 <thead> 
  <tr> 
   <th align="left">Parameter Name</th> 
   <th align="left">Type</th> 
   <th align="left">Description</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td align="left">interval<br>间隔</td> 
   <td align="left">integer</td> 
   <td align="left"><code>How often</code> a rollover should occur based on the most <code>specific time unit</code> in the date pattern. For example, with <code>a date pattern with hours</code> as the most specific item and increment of 4 rollovers would occur every 4 hours. The <code>default value is 1</code>.<br>基于filePattern中配置的最小时间单位进行来控制归档频率，默认值为1。如：filePattern中最小时间单位为小时，如果interval=1，则1小时归档一次；如果interval=2，则2小时归档一次。</td> 
  </tr> 
  <tr> 
   <td align="left">modulate<br>调整</td> 
   <td align="left">boolean</td> 
   <td align="left">Indicates whether the interval should be adjusted to cause the next rollover to occur <code>on the interval boundary</code>. For example, if the item is hours, the current hour is 3 am and the interval is 4 then the first rollover will occur at 4 am and then next ones will occur at 8 am, noon, 4pm, etc. The <code>default value is false</code>.<br>默认为false。指明是否对interval进行调节，若modulate为true，会以0为开始对interval进行偏移计算。例如，最小时间粒度为小时，当前为3:00，interval为4，则后面归档时间依次为4:00，8:00，12:00，16:00</td> 
  </tr> 
  <tr> 
   <td align="left">maxRandomDelay<br>最大随机延迟</td> 
   <td align="left">integer</td> 
   <td align="left">Indicates the maximum number of seconds to randomly delay a rollover. <code>By default, this is 0 which indicates no delay</code>. This setting is useful on <code>servers where multiple applications are configured</code> to rollover log files at the same time and can spread the load of doing so across time.<br>指示随机延迟过渡的最大秒数。默认情况下，该值为0，表示没有延迟。此设置在配置了多个应用程序以同时滚动日志文件的服务器上很有用，并且可以在整个时间上分散这样做的负担。</td> 
  </tr> 
 </tbody> 
</table>

--------------------

#### 验证1：`<TimeBasedTriggeringPolicy interval="1"/>` ####

<?xml version="1.0" encoding="UTF-8"?>
    <configuration status="info" monitorInterval="10">
    
        <properties>
            <property name="LOG_HOME">./applog/logs</property>
            <Property name="FILE_NAME" value="practisesvr"/>
            <Property name="LOG_PATTERN" value="[%d{yyyy-MM-dd HH:mm:ss}] [%-5level] [%thread] [%file:%line] → [%enc{%m}{CRLF}]%n"/>
        </properties>
    
        <appenders>
            <RollingFile name="SIZE_BASED_TRIGGERING"
                         fileName="${LOG_HOME}/${FILE_NAME}.log"
                         filePattern="${LOG_HOME}/${FILE_NAME}_%d{yyyy-MM-dd-HH-mm-ss}_%i.log" createOnDemand="true">
                <ThresholdFilter level="info" onMatch="ACCEPT" onMismatch="DENY"/>
                <PatternLayout pattern="${LOG_PATTERN}"/>
                <Policies>
                    <TimeBasedTriggeringPolicy interval="1"/>
                </Policies>
                <DefaultRolloverStrategy max="5"/>
            </RollingFile>
        </appenders>
    
        <loggers>
            <root level="all">
                <AppenderRef ref="SIZE_BASED_TRIGGERING"/>
            </root>
        </loggers>
    </configuration>

上述模板中

*  日志先写入`practisesvr.log`中，每经过`1s`时（`filePattern`中`最小时间单位`为`秒`），按照在`./applog/logs`目录下以`practisesvr_2023-04->02_1.log`格式对该日志进行`压缩重命名并归档`，并生成新的文件`practisesvr.log`进行日志写入。

--------------------

#### 验证2：验证分钟场景 ####

##### `modulate="false"` #####

filePattern="${LOG_HOME}/${FILE_NAME}_%d{yyyy-MM-dd-HH-mm}_%i.log"
    <TimeBasedTriggeringPolicy modulate="false" interval="3"/>

2023-04-03 01:22:05 ：启动服务开始记录第一条日志
    
    practisesvr_2023-04-03-01-24_1.log
    2023-04-03 01:22:05
    2023-04-03 01:24:59
    
    practisesvr_2023-04-03-01-27_1.log
    2023-04-03 01:25:00
    2023-04-03 01:27:59

--------------------

##### `modulate="true"` #####

filePattern="${LOG_HOME}/${FILE_NAME}_%d{yyyy-MM-dd-HH-mm}_%i.log"
    <TimeBasedTriggeringPolicy modulate="true" interval="2"/>

2023-04-03 00:44:18：启动服务开始记录第一条日志
    
    practisesvr_2023-04-03-00-45_1.log
    2023-04-03 00:44:18  本日志文件：启动服务开始记录第一条日志
    2023-04-03 00:45:59  本日志文件最后一条日志
    
    practisesvr_2023-04-03-00-47_1.log
    2023-04-03 00:46:00 本日志文件开始时间
    2023-04-03 00:47:59 本日志文件结束时间
    
    practisesvr_2023-04-03-00-49_1.log
    2023-04-03 00:48:00 本日志文件开始时间
    2023-04-03 00:49:59 本日志文件结束时间

--------------------

filePattern="${LOG_HOME}/${FILE_NAME}_%d{yyyy-MM-dd-HH-mm}_%i.log"
    <TimeBasedTriggeringPolicy modulate="true" interval="3"/>

2023-04-03 00:52:09 启动服务开始记录第一条日志
    
    practisesvr_2023-04-03-00-53_1.log
    2023-04-03 00:52:09 本日志文件：启动服务开始记录第一条日志
    2023-04-03 00:53:59 本日志文件最后一条日志
    
    practisesvr_2023-04-03-00-56_1.log
    2023-04-03 00:54:00 本日志文件开始时间
    2023-04-03 00:56:59 本日志文件结束时间
    
    practisesvr_2023-04-03-00-59_1.log
    2023-04-03 00:57:00 本日志文件开始时间
    2023-04-03 00:59:59 本日志文件结束时间

#### 验证3：验证小时场景 ####

##### `modulate="true"` #####

<?xml version="1.0" encoding="UTF-8"?>
    <configuration status="info" monitorInterval="10">
    
        <properties>
            <property name="LOG_HOME">./applog/logs</property>
            <Property name="FILE_NAME" value="practisesvr"/>
            <Property name="LOG_PATTERN" value="[%d{yyyy-MM-dd HH:mm:ss}] [%-5level] [%thread] [%file:%line] → [%enc{%m}{CRLF}]%n"/>
        </properties>
    
        <appenders>
            <RollingFile name="SIZE_BASED_TRIGGERING"
                         fileName="${LOG_HOME}/${FILE_NAME}.log"
                         filePattern="${LOG_HOME}/${FILE_NAME}_%d{yyyy-MM-dd-HH}_%i.log"
                         createOnDemand="true">
                <ThresholdFilter level="info" onMatch="ACCEPT" onMismatch="DENY"/>
                <PatternLayout pattern="${LOG_PATTERN}"/>
                <Policies>
                    <TimeBasedTriggeringPolicy modulate="true" interval="3"/>
                </Policies>
                <DefaultRolloverStrategy fileIndex = "nomax"/>
            </RollingFile>
        </appenders>
    
        <loggers>
            <root level="all">
                <AppenderRef ref="SIZE_BASED_TRIGGERING"/>
            </root>
        </loggers>
    </configuration>

2023-04-03 08:56:19 启动服务开始记录第一条日志
    
    practisesvr_2023-04-03-08_1.log
    2023-04-03 08:56:19 本日志文件：启动服务开始记录第一条日志
    2023-04-03 08:59:59 本日志文件最后一条日志
    
    practisesvr_2023-04-03-11_1.log
    2023-04-03 09:00:00 本日志文件开始时间
    2023-04-03 11:59:59 本日志文件结束时间

如上`modulate="true"`设置后，假如`8点56分`的日志开始重启服务，日志先写入`logs/app.log`中则`9点`触发一次rollover操作，生成`practisesvr_2023-04-03-08_1.log`对该日志进行`压缩重命名并归档`，并`生成新的文件practisesvr.log进行日志写入`；然后，每间隔`3小时`，则下一次是`12点`触发一次rollover。

--------------------

##### `modulate="false"` #####

<TimeBasedTriggeringPolicy modulate="false" interval="3"/>
    
    2023-04-03 13:50:34 启动服务开始记录第一条日志
    
    practisesvr_2023-04-03-15_1.log
    2023-04-03 13:50:34 启动服务开始记录第一条日志
    2023-04-03 15:59:59 本日志文件结束时间

--------------------

### 3.3 （3）Composite Triggering Policy：基于时间间隔和文件大小的滚动策略 ###

The CompositeTriggeringPolicy combines multiple triggering policies and returns true if `any` of the configured policies return true.  
可以理解为取下限，先满足哪个策略条件就基于哪个策略生成log文件

<?xml version="1.0" encoding="UTF-8"?>
    <configuration status="info" monitorInterval="10">
    
        <properties>
            <property name="LOG_HOME">./applog/logs</property>
            <Property name="FILE_NAME" value="practisesvr"/>
            <Property name="LOG_PATTERN" value="[%d{yyyy-MM-dd HH:mm:ss}] [%-5level] [%thread] [%file:%line] → [%enc{%m}{CRLF}]%n"/>
        </properties>
    
        <appenders>
            <RollingFile name="SIZE_BASED_TRIGGERING"
                         fileName="${LOG_HOME}/${FILE_NAME}.log"
                         filePattern="${LOG_HOME}/${FILE_NAME}_%d{yyyy-MM-dd-HH}_%i.log.gz"
                         createOnDemand="true">
                <ThresholdFilter level="info" onMatch="ACCEPT" onMismatch="DENY"/>
                <PatternLayout pattern="${LOG_PATTERN}"/>
                <Policies>
                    <TimeBasedTriggeringPolicy modulate="true" interval="6"/>
                    <SizeBasedTriggeringPolicy size="100MB"/>
                </Policies>
                <DefaultRolloverStrategy fileIndex = "nomax"/>
            </RollingFile>
        </appenders>
    
        <loggers>
            <root level="all">
                <AppenderRef ref="SIZE_BASED_TRIGGERING"/>
            </root>
        </loggers>
    </configuration>

上述模板中，日志先写入`practisesvr.log`中，每当文件大小达到`100MB`或者当时间间隔到达`6小时`（由`%d{yyyy-MM-dd-HH}`决定），触发rollover操作，按照在`./applog/logs`目录下以`practisesvr_2023-04-03-11_1.log.gz`格式对该日志进行压缩重命名并归档，并生成新的文件`practisesvr.log`进行日志写入。

--------------------

## 4. `<DefaultRolloverStrategy>` ##

### 4.1 DefaultRolloverStrategy Parameters ###

--------------------

### 4.2 Delete Parameters ###

<table> 
 <thead> 
  <tr> 
   <th align="left">Parameter Name</th> 
   <th align="left">Type</th> 
   <th align="left">Description</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td align="left"><code>basePath</code></td> 
   <td align="left">String</td> 
   <td align="left"><em><code>Required</code>.</em> Base path from <code>where</code> to start <code>scanning</code> for files <code>to delete</code>.</td> 
  </tr> 
  <tr> 
   <td align="left"><code>maxDepth</code></td> 
   <td align="left">int</td> 
   <td align="left">The maximum number of levels of directories to visit. A value of <code>0</code> means that only the starting file (<code>the base path itself</code>) is visited, unless denied by the security manager. A value of <code>Integer.MAX_VALUE</code> indicates that <code>all levels</code> should be visited. <code>The default is 1</code>, meaning only the files in the specified base directory.</td> 
  </tr> 
  <tr> 
   <td align="left">followLinks</td> 
   <td align="left">boolean</td> 
   <td align="left">Whether to follow symbolic links. Default is false.</td> 
  </tr> 
  <tr> 
   <td align="left">testMode</td> 
   <td align="left">boolean</td> 
   <td align="left">If true, files are not deleted but instead a message is printed to the <a href="https://logging.apache.org/log4j/2.x/manual/configuration.html#StatusMessages" rel="nofollow">status logger</a> at INFO level. Use this to do a dry run to test if the configuration works as expected. Default is false.</td> 
  </tr> 
  <tr> 
   <td align="left">pathSorter</td> 
   <td align="left">PathSorter</td> 
   <td align="left">A plugin implementing the <a href="https://logging.apache.org/log4j/2.x/log4j-core/apidocs/org/apache/logging/log4j/core/appender/rolling/action/PathSorter.html" rel="nofollow">PathSorter</a> interface to sort the files before selecting the files to delete. The default is to sort most recently modified files first.</td> 
  </tr> 
  <tr> 
   <td align="left">pathConditions</td> 
   <td align="left">PathCondition[]</td> 
   <td align="left"><em>Required if no ScriptCondition is specified.</em> One or more PathCondition elements.If more than one condition is specified, they all need to accept a path before it is deleted. Conditions can be nested, in which case the inner condition(s) are evaluated only if the outer condition accepts the path. If conditions are not nested they may be evaluated in any order.Conditions can also be combined with the logical operators AND, OR and NOT by using the <code>IfAll</code>, <code>IfAny</code> and <code>IfNot</code> composite conditions.Users can create custom conditions or use the built-in conditions:<br><a href="https://logging.apache.org/log4j/2.x/manual/appenders.html#DeleteIfFileName" rel="nofollow">IfFileName</a> - accepts files whose path (relative to the base path) matches a <a href="https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html" rel="nofollow">regular expression</a> or a <a href="https://docs.oracle.com/javase/7/docs/api/java/nio/file/FileSystem.html#getPathMatcher%28java.lang.String%29" rel="nofollow">glob</a>.<br><a href="https://logging.apache.org/log4j/2.x/manual/appenders.html#DeleteIfLastModified" rel="nofollow">IfLastModified</a> - accepts files that are as old as or older than the specified <a href="https://logging.apache.org/log4j/2.x/log4j-core/apidocs/org/apache/logging/log4j/core/appender/rolling/action/Duration.html#parseCharSequence" rel="nofollow">duration</a>.<br>IfFileName 和 IfLastModified 都属于 pathConditions。pathConditions 是一个数组，决定哪些文件会被删除，如果定义了多个，需要多个条件同时满足才会被删除<a href="https://logging.apache.org/log4j/2.x/manual/appenders.html#DeleteIfAccumulatedFileCount" rel="nofollow">IfAccumulatedFileCount</a> - accepts paths after some count threshold is exceeded during the file tree walk.<br><a href="https://logging.apache.org/log4j/2.x/manual/appenders.html#DeleteIfAccumulatedFileSize" rel="nofollow">IfAccumulatedFileSize</a> - accepts paths after the accumulated file size threshold is exceeded during the file tree walk.<br><code>IfAll</code> - accepts a path if all nested conditions accept it (logical AND). Nested conditions may be evaluated in any order.<br><code>IfAny</code> - accepts a path if one of the nested conditions accept it (logical OR). Nested conditions may be evaluated in any order.<br><code>IfNot</code> - accepts a path if the nested condition does not accept it (logical NOT).<br></td> 
  </tr> 
  <tr> 
   <td align="left">scriptCondition</td> 
   <td align="left">ScriptCondition</td> 
   <td align="left"><em>Required if no PathConditions are specified.</em> A ScriptCondition element specifying a script.The ScriptCondition should contain a <a href="https://logging.apache.org/log4j/2.x/manual/appenders.html#ScriptCondition" rel="nofollow">Script, ScriptRef or ScriptFile</a> element that specifies the logic to be executed. (See also the <a href="https://logging.apache.org/log4j/2.x/manual/filters.html#Script" rel="nofollow">ScriptFilter</a> documentation for more examples of configuring ScriptFiles and ScriptRefs.)The script is passed a number of <a href="https://logging.apache.org/log4j/2.x/manual/appenders.html#ScriptParameters" rel="nofollow">parameters</a>, including a list of paths found under the base path (up to <code>maxDepth</code>) and must return a list with the paths to delete.</td> 
  </tr> 
 </tbody> 
</table>

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### 4.3 IfFileName Condition Parameters ###

指定删除的文件格式，只要符合条件都会被删除

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### 4.4 IfLastModified Condition Parameters ###

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### 4.5 IfAccumulatedFileCount Condition Parameters ###

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### 4.6 IfAccumulatedFileSize Condition Parameters ###

[https_logging.apache.org_log4j_2.x_manual_filters.html]: https://logging.apache.org/log4j/2.x/manual/filters.html
[79932046f0ee4b36911f4630d6def253.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/24/4f77aa2769cb48bdbb7eda2478e4486b.png