How to Create 2 Separate Log Files with One Log4J Config File

How can I create 2 separate log files with one log4j config file?

Try the following configuration:

log4j.rootLogger=TRACE, stdout

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d [%24F:%t:%L] - %m%n

log4j.appender.debugLog=org.apache.log4j.FileAppender
log4j.appender.debugLog.File=logs/debug.log
log4j.appender.debugLog.layout=org.apache.log4j.PatternLayout
log4j.appender.debugLog.layout.ConversionPattern=%d [%24F:%t:%L] - %m%n

log4j.appender.reportsLog=org.apache.log4j.FileAppender
log4j.appender.reportsLog.File=logs/reports.log
log4j.appender.reportsLog.layout=org.apache.log4j.PatternLayout
log4j.appender.reportsLog.layout.ConversionPattern=%d [%24F:%t:%L] - %m%n

log4j.category.debugLogger=TRACE, debugLog
log4j.additivity.debugLogger=false

log4j.category.reportsLogger=DEBUG, reportsLog
log4j.additivity.reportsLogger=false

Then configure the loggers in the Java code accordingly:

static final Logger debugLog = Logger.getLogger("debugLogger");
static final Logger resultLog = Logger.getLogger("reportsLogger");

Do you want output to go to stdout? If not, change the first line of log4j.properties to:

log4j.rootLogger=OFF

and get rid of the stdout lines.

How to create multiple log files of different content with log4j

Finally I found the way of doing this.

# Root logger option
log4j.rootLogger=TRACE, stdout, file

log4j.category.testngLogger=DEBUG, testng
log4j.additivity.testngLogger=false

In rootLogger, that is like a father of all logs. It inherit by default. Root logger option should be like that.

If you additivity set to false it will never goes to rootLogger

In log4j.xml file it will goes like this.

<logger name="testngLogger" additivity="false">
    <level value="DEBUG" />
    <appender-ref ref="testngLogger" />
</logger>

<root>
    <priority value="INFO" />
    <appender-ref ref="CONSOLE" />
    <appender-ref ref="fileLogger" />
</root>

How to create multiple log files in log4j2 using property file?

Please set additivity=false for both named loggers.

Also, add a root logger configuration to tell Log4j2 where to send the logging calls other than the “file1” and “file2” loggers:

rootLogger.level = info
rootLogger.appenderRef.stdout.ref = STDOUT

Also, give your named loggers a unique prefix:

logger.aaa.name = file1
logger.aaa.additivity = false
logger.aaa.level = debug
logger.aaa.appenderRef.rrr.ref = RollingFile1

logger.bbb.name = file2
logger.bbb.additivity = false
logger.bbb.level = debug
logger.bbb.appenderRef.sss.ref = RollingFile2

How to create two log files

The file name can be parameterized in the log4j.properties file and passed as a JVM argument,

log4j.appender.file = org.apache.log4j.RollingFileAppender
log4j.appender.file.File = ${ApplicationName}.log

Can pass the ApplicationName as a JVM argument with actual file name,

-DApplicationName=Myapp1

Same log4j.properties file can be shared by both applications and you can pass the application name in the JVM parameter for each application.

Multiple log files with log4j

Of cource, use different FileAppenders
Example from internet:

log4j.rootLogger=DEBUG

# AdminFileAppender - used to log messages in the admin.log file.
log4j.appender.AdminFileAppender=org.apache.log4j.FileAppender

log4j.appender.AdminFileAppender.File=admin.log

log4j.appender.AdminFileAppender.layout=org.apache.log4j.PatternLayout
log4j.appender.AdminFileAppender.layout.ConversionPattern= %-4r [%t] %-5p %c %x - %m%n

# ReportFileAppender - used to log messages in the report.log file.
log4j.appender.ReportFileAppender=org.apache.log4j.FileAppender

log4j.appender.ReportFileAppender.File=report.log

log4j.appender.ReportFileAppender.layout=org.apache.log4j.PatternLayout
log4j.appender.ReportFileAppender.layout.ConversionPattern= %-4r [%t] %-5p %c %x - %m%n

log4j.logger.com.vaannila.admin=WARN,AdminFileAppender 
log4j.logger.com.vaannila.report=DEBUG,ReportFileAppender

Now you can log to admin.log Logger.getLogger("com.vaannila.admin").log("To admin log") and to report log Logger.getLogger("com.vaannila.report").log("To report log")

In Apache Log4J, Is there a way to simply create multiple log files on the fly, rather than appending to one log file?

Yes, you can use the RoutingAppender. See this question for details: Log4j2: Dynamic creation of log files for multiple logs