Log4net rolling daily filename with date in the file name

Question

I would like to have files named for example:

dd.mm.yyyy.log

How is this possible with log4net?

Possible duplicate of [Log4net appender filename issue](http://stackoverflow.com/questions/2833464/log4net-appender-filename-issue) — Narottam Goyal, Feb 14 '17 at 10:31

score 232 · Answer 1 · edited Oct 01 '13 at 13:43

232

<appender name="RollingLogFileAppender" type="log4net.Appender.RollingFileAppender">
  <lockingModel type="log4net.Appender.FileAppender+MinimalLock"/>
  <file value="logs\" />
  <datePattern value="dd.MM.yyyy'.log'" />
  <staticLogFileName value="false" />
  <appendToFile value="true" />
  <rollingStyle value="Composite" />
  <maxSizeRollBackups value="10" />
  <maximumFileSize value="5MB" />
  <layout type="log4net.Layout.PatternLayout">
    <conversionPattern value="%date [%thread] %-5level %logger [%property{NDC}] - %message%newline" />
  </layout>
</appender>

edited Oct 01 '13 at 13:43

Philipp M

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answered Nov 24 '11 at 10:31

Nonkichi

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I think you should highlight the main point of what parameter to solve the problem as @Mun did. However, I also voted up for your answer. – NoName Feb 24 '16 at 07:25
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It was the datePattern element, in conjunction with the staticLogFileName element (and note the value attribute for the file element) that worked for me – Michhes Oct 24 '17 at 05:37
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The complete answer! – Nagesh Jun 25 '20 at 13:50

score 113 · Accepted Answer · answered Jul 22 '09 at 13:02

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In your Log4net config file, use the following parameter with the RollingFileAppender:

<param name="DatePattern" value="dd.MM.yyyy'.log'" />

answered Jul 22 '09 at 13:02

Mun

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Appears this has been promoted to a config element: Cheers! – longda May 29 '13 at 00:11
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@mstaessen `` is the correct syntax and this is a great answer. How did the loss occur, may I ask? – Larry Beasley Feb 12 '18 at 14:48
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If I recall correctly, it went like this. On startup, log4net would generate the first filename in the rolling sequence. It would detect that that file already exist and would then decide to roll to the second file, but when that one also already exists, it does not decide to roll but instead clears it and overwrites everything in that second log file. It goes by totally unnoticed until you need logs of the cleared timeframe... – mstaessen Feb 12 '18 at 15:11

score 33 · Answer 3 · answered Jan 15 '10 at 23:47

33

For a RollingLogFileAppender you also need these elements and values:

<rollingStyle value="Date" />
<staticLogFileName value="false" />

answered Jan 15 '10 at 23:47

BobD

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This works, but appends the date after the file extension. For example I get log files like Error.log20111104 - Does anyone know of a way to format the file name a little better? – LostNomad311 Nov 04 '11 at 13:12
Here's how to format the file name better: http://stackoverflow.com/questions/615092/log4net-rolling-file-appender-define-extension/615137#615137 – LostNomad311 Nov 04 '11 at 13:17
what is staticLogFileName used for? I only want the log file to be rolled into a new name after the day ends. I want to use a log monitor that looks at a specific each time. – Sun Aug 14 '14 at 15:33

Njal · Answer 4 · 2017-02-01T10:17:34.047

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I ended up using (note the '.log' filename and the single quotes around 'myfilename_'):

  <rollingStyle value="Date" />
  <datePattern value="'myfilename_'yyyy-MM-dd"/>
  <preserveLogFileNameExtension value="true" />
  <staticLogFileName value="false" />
  <file type="log4net.Util.PatternString" value="c:\\Logs\\.log" />

This gives me:

myfilename_2015-09-22.log
myfilename_2015-09-23.log
.
.

edited Feb 01 '17 at 10:17

answered Sep 23 '15 at 14:52

Njal

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`preserveLogFileNameExtension` doesn't work for earlier versions of log4net (e.g. v1.2.10) as it's described [here](https://stackoverflow.com/questions/27276647/log4net-preservelogfilenameextension-not-working) – Dmitry Karpenko Nov 08 '18 at 12:53

score 24 · Answer 5 · answered Apr 17 '15 at 13:46

Using Log4Net 1.2.13 we use the following configuration settings to allow date time in the file name.

<file type="log4net.Util.PatternString" value="E:/logname-%utcdate{yyyy-MM-dd}.txt" />

Which will provide files in the following convention: logname-2015-04-17.txt

With this it's usually best to have the following to ensure you're holding 1 log per day.

<rollingStyle value="Date" />
<datePattern value="yyyyMMdd" />

If size of file is a concern the following allows 500 files of 5MB in size until a new day spawns. CountDirection allows Ascending or Descending numbering of files which are no longer current.

 <maxSizeRollBackups value="500" />
 <maximumFileSize value="5MB" />
 <rollingStyle value="Composite" />
 <datePattern value="yyyyMMdd" />
 <CountDirection value="1"/>
 <staticLogFileName value="true" />

Matt · Answer 6 · 2019-06-24T08:01:49.827

I've tried all the answers, but there was always something missing and not functioning as expected for me.

Then I experimented a bit with the hints given in each answer and was successful with the following setting:

<appender name="RollingActivityLog" type="log4net.Appender.RollingFileAppender">
  <file type="log4net.Util.PatternString" value="C:\temp\LOG4NET_Sample_Activity.log" />
  <appendToFile value="true" />
  <rollingStyle value="Date" />
  <staticLogFileName value="false" />
  <preserveLogFileNameExtension value="true" />
  <datePattern value="-yyyyMMdd" />
  <layout type="log4net.Layout.PatternLayout">
    <conversionPattern value="%date %-5level - %message%newline" />
  </layout>
</appender>

The issue with other combinations of parameters was that the latest file didn't have the time pattern, or that the time pattern was appended as .log20171215 which created a new file time (and a new file type!) each day - or both issues appeared.

Now with this setting you are getting files like this one:

LOG4NET_Sample_Activity-20171215.log

which is what I wanted.

To summarize:

Don't put the date pattern in the <file value=... attribute, just define it in the datePattern.
Make sure you have the preserveLogFileNameExtension value attribute set to true.
Make sure you have the staticLogFileName value set to false.
Set the rollingStyle attribute value to Date.

You can also set rollingStyle to Composite, which rolls on both date and size. — Simon Elms, Nov 02 '18 at 01:10
Works great. I would also add in the summarize: Make sure you have the staticLogFileName value set to false — Randall Flagg, Jun 23 '19 at 10:23

score 6 · Answer 7 · answered Dec 15 '16 at 21:11

6

To preserve file extension:

<log4net>
    <root>
      <level value="DEBUG"/>
      <appender-ref ref="RollingLogFileAppender"/>
    </root>
    <appender name="RollingLogFileAppender" type="log4net.Appender.RollingFileAppender">
      <file type="log4net.Util.PatternString" value="D:\\LogFolder\\%date{yyyyMM}\\SchT.log" />
      <appendToFile value="true" />
      <rollingStyle value="Date" />
      <maximumFileSize value="30MB" />
      <staticLogFileName value="true" />
      <preserveLogFileNameExtension value="true"/>
      <datePattern value="ddMMyyyy" />
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%date [%thread] %-5level %logger - %message%newline" />
      </layout>
    </appender>
  </log4net>

answered Dec 15 '16 at 21:11

Fourat

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why there are `%date{yyyyMM}` and `value="ddMMyyyy" `? which is the effective date pattern? – Allan Ruin Aug 17 '17 at 08:34
I think datePattern is for the file name but %date{yyyyMM} is for the parent directory (I wanted it that way) – Fourat Aug 17 '17 at 13:13
The datePattern attribute sets the rolling period for Date rollingStyle. See https://logging.apache.org/log4net/release/config-examples.html under RollingFileAppender. "For example, a date pattern of "yyyyMMdd" will roll every day. See System.Globalization.DateTimeFormatInfo for a list of available patterns." – Ryan Buddicom Jan 25 '18 at 22:21
@rbuddicom yeah but the question is about how to preserve file extension. – Fourat Jan 26 '18 at 08:47
I know, Allan questioned the purpose of 'value="ddMMyyyy"'. Your comment "I think datePattern is for the file name" is incorrect in that regard. – Ryan Buddicom Jan 29 '18 at 20:04
@rbuddicom The datePattern indicates the pattern (or frequency) to roll the file which will be mentioned in the file name (or parent directory name if you want it). If you check the example in my answer you will see that the file is `SchT.log` and with `` the files will be named for ex: `201801\SchT30012018.log`. Moreover, if you look closely to the comment you'll see that Allen Ruin asked why there are `%date{yyyyMM}` and `value="ddMMyyyy"` and which is the effective. I answered and explained the role of each pattern and specified that I wanted it that way. – Fourat Jan 30 '18 at 08:19
@Fourat fair enough :) – Ryan Buddicom Jan 30 '18 at 23:01

score 0 · Answer 8 · answered Mar 23 '20 at 22:47

I moved configuration to code to enable easy modification from CI using system variable. I used this code for file name and result is 'Log_03-23-2020.log'

            log4net.Repository.ILoggerRepository repository = LogManager.GetRepository(Assembly.GetEntryAssembly());
            Hierarchy hierarchy = (Hierarchy)repository;
            PatternLayout patternLayout = new PatternLayout();
            patternLayout.ConversionPattern = "%date %level - %message%newline%exception";
            patternLayout.ActivateOptions();

            RollingFileAppender roller = new RollingFileAppender();
            roller.AppendToFile = true;
            roller.File = "Log_";
            roller.DatePattern = "MM-dd-yyyy'.log'";
            roller.Layout = patternLayout;
            roller.MaxFileSize = 1024*1024*10;
            roller.MaxSizeRollBackups = 10;
            roller.StaticLogFileName = false;
            roller.RollingStyle = RollingFileAppender.RollingMode.Composite;
            roller.ActivateOptions();
            hierarchy.Root.AddAppender(roller);

score 0 · Answer 9 · answered Oct 23 '22 at 20:45

Your answer is that the way to changing "rollingStyle value" to "Date". The others things are look like fine.

<rollingStyle value="Date" />

The trick is hidden those four definitions:

 ...
  <file value="logs\" />
  <datePattern value="dd.MM.yyyy'.log'" />
  <staticLogFileName value="false" />
  <rollingStyle value="Date" />
  ...

This is my log4net configuration:

    <?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <!-- Log4Net -->
    <configSections>
        <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" />
    </configSections>
    <log4net>
        <root>
            <level value="ALL" />
            <appender-ref ref="RollingFileAppender" />
        </root>
        <appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender">
            <file value="logs\log_" />
            <rollingStyle value="Date" />
            <datePattern value="yyyy_MM_dd'.txt'"/>
            <staticLogFileName value="false" />
            <appendToFile value="true" />
            <maxSizeRollBackups value="50" />
            <maximumFileSize value="10MB" />
            <lockingModel type="log4net.Appender.FileAppender+MinimalLock" />
            <layout type="log4net.Layout.PatternLayout">
                <conversionPattern value="%date [%thread] %level - %message%newline%exception" />
            </layout>
            <filter type="log4net.Filter.LevelRangeFilter">
                <levelMin value="INFO" />
                <levelMax value="ERROR" />
                <levelMin value="DEBUG" />
            </filter>
        </appender>
    </log4net>
    <!-- Log4Net -->
</configuration>

Fred Smith · Answer 10 · 2022-11-04T15:38:35.300

for me, the solution was to modify the datePattern value like this:

<datePattern value="'-'yyyy-MM-dd'.log'" />

Here is my appender:

<appender name="testAppender" type="log4net.Appender.RollingFileAppender">
<file  type="log4net.Util.PatternString" value="ApplicationLog" />
<appendToFile value="true" />
<rollingStyle value="Date" />
<staticLogFileName value="false" />
<preserveLogFileNameExtension value="true" />
<datePattern value="'-'yyyy-MM-dd'.log'" />
<maxSizeRollBackups value="10" />
<maximumFileSize value="100MB" />
<layout type="log4net.Layout.PatternLayout">
  <conversionPattern value="%date %-5level - %message%newline" />
</layout>

My log file will be named: ApplicationLog-2022-11-04.log

score 0 · Answer 11 · answered Mar 21 '12 at 21:42

0

The extended configuration section in a previous response with

 ...
 ...
 <rollingStyle value="Composite" />
 ...
 ...

listed works but I did not have to use

<staticLogFileName value="false" />

. I think the RollingAppender must (logically) ignore that setting since by definition the file gets rebuilt each day when the application restarts/reused. Perhaps it does matter for immediate rollover EVERY time the application starts.

answered Mar 21 '12 at 21:42

AllenM

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For me, it wouldn't work without the – nurettin Aug 16 '12 at 08:02
me as well, had to set staticLogFileName to false otherwise it wouldn't log – oonyalo Aug 02 '16 at 19:46

Log4net rolling daily filename with date in the file name

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