How to give environmental variable path for file appender in configuration file in log4j

Question

I have a log4j xml config file  and a RollingFileAppender to which I need to provide file path for storing logs  The problem is my code will be deployed on Unix machine as a runnable jar  So if I pass parameter something like this   value logs messages log    it creates folder named logs inside my HOME directory and writes all the messages to file inside this directory    I have a environmental variable set to some value  I want to use path of that variable and write messages under that path  How can I achieve it   I had tried using this   value    MY HOME  logs message log    but this does not work  Can anyone suggest a solution for this problem

User · Accepted Answer

When parsing its configuration file  the expression   MY HOME  will be expanded to the value of the system property named MY HOME  not the system environment variable  There s a difference between the two   To achieve this in a clean way  you ll have to add something like this to the JVM invocation line   -DMY HOME  MY HOME  That would define the Java system property MY HOME to contain the value of the environment variable MY HOME

User · Answer

To dynamically change a variable you can do something like this   String value   System getenv  MY HOME    Properties prop   new Properties  log4j properties     prop put  MY HOME   value      overwrite with value from environment PropertyConfigurator configure prop

User · Answer

Maybe        datestamp yyyy-MM-dd HH mm ss SSS zzz layout  d   datestamp   ms  -4r   t   -5p  l  n m  n n    infoFile  log4j appender infoFile org apache log4j RollingFileAppender log4j appender infoFile File   MY HOME  logs message log log4j appender infoFile layout org apache log4j PatternLayout log4j appender infoFile layout ConversionPattern   layout

User · Answer

This syntax is documented only in log4j 2 X so make sure you are using the correct version        lt Appenders gt       lt File name  file  fileName    env LOG PATH   gt           lt PatternLayout gt               lt Pattern gt  d  p  c 1     t   m  ex n lt  Pattern gt           lt  PatternLayout gt       lt  File gt   lt  Appenders gt    http   logging apache org log4j 2 x manual lookups html EnvironmentLookup

User · Answer

Log4j entry   - File to log to and log format  log4j appender file File   LOG PATH  mylogfile log  Java program String log4jConfPath           path log4j properties   File log4jFile                new File log4jConfPath   if  log4jFile exists          System setProperty  LOG PATH    c  temp         PropertyConfigurator configure log4jFile getAbsolutePath         logger trace  test123

User · Answer

I got this working    In my log4j properties  I specified       log4j appender file File   LogFilePath     in eclipse - JVM arguments       -DLogFilePath C  work MyLogFile log

User · Answer

you CAN give it environment variables  Just preppend env  before the variable name  like this   value    env MY HOME  logs message log

User · Answer

Since you are using unix you can use a path like this      home Production modulename logs message log   path should start with

User · Answer

java -DLOG DIR   LOG DIR  -jar myjar jar  param1   param2        in cmd line if you have   value    LOG DIR  log clientProject project-error log  in xml

[java] How to give environmental variable path for file appender in configuration file in log4j

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