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Can anyone please guide me as to how I can configure log4j to log to a specific file that I specify at run-time.The name and path of the log file are generated at run-time and the application must log to that particular file.
Generally file appender entries in the log4j.properties file points to the log file that will be used by the application.However in this case I would like to read the log file path from the command line and log to that particular file.
How can I achieve this ?
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Use LogManager. resetConfiguration(); to clear the current config and configure it again. Another approach is to build a new appender and replace the old one with it (most appenders don't support changing their config).
System. setProperty("{my. log", "C:/logfile. log");
File with system properties name and some prefix text if you want. This will create a log file with current date time, something like this Log4jDemoApp-dd-MM-yyyy-hh-mm-ss. log every time we run the application. It will create the new file because for every run we are setting current date stamp in system properties.
You can also do this from the log4j.properties file. Using the sample file below I have added the system property ${logfile.name}:
# logfile is set to be a RollingFileAppender log4j.appender.logfile=org.apache.log4j.RollingFileAppender log4j.appender.logfile.File=${logfile.name} log4j.appender.logfile.MaxFileSize=10MB log4j.appender.logfile.layout=org.apache.log4j.PatternLayout log4j.appender.logfile.layout.ConversionPattern=[%-5p]%d{yyyyMMdd@HH\:mm\:ss,SSS}\:%c - %m%n The log file name can then be set two different ways:
In the java program directly by setting a system property (BEFORE you make any calls to log4j).
System.setProperty("logfile.name","some path/logfile name string");
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