Log4cxx properties file variable substitution

Question

I have a properties file for log4cxx configuration with a variable name ${name}:

Properties file example:

log4j.rootLogger=INFO, FILE

# FILE
log4j.appender.FILE=org.apache.log4j.RollingFileAppender
log4j.appender.FILE.File=./${name}
log4j.appender.FILE.MaxFileSize=16MB
log4j.appender.FILE.MaxBackupIndex=10
log4j.appender.FILE.layout=org.apache.log4j.PatternLayout
log4j.appender.FILE.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss.SSS} %-5p %m%n

How can I set the variable ${name} from my cpp file or cmake file. I tried with the following code but it doesn't work:

#include <log4cxx/logger.h>
#include <log4cxx/propertyconfigurator.h>
#include <log4cxx/helpers/properties.h>

using namespace log4cxx;

static LoggerPtr logger(Logger::getLogger(""));

int main() {
    PropertyConfigurator::configure("./assets/logger.properties");

#ifndef NDEBUG
    logger->setLevel(log4cxx::Level::getDebug());
#endif

    return EXIT_SUCCESS;
}

Thanks in advance

Answer 1

Found out the solution: Use setenv from stdlib. Here is the working solution:

#include <stdlib.h> // Include the library
#include <log4cxx/logger.h>
#include <log4cxx/propertyconfigurator.h>
#include <log4cxx/helpers/properties.h>

using namespace log4cxx;

static LoggerPtr logger(Logger::getLogger(""));

int main() {
    // Set the env variable
    // The identifier must be the same as the one in the log4cxx configuration file
    setenv("name", "NAME_OF_THE_CURRENT_LOG_FILE", true);

    PropertyConfigurator::configure("./assets/logger.properties");

#ifndef NDEBUG
    logger->setLevel(log4cxx::Level::getDebug());
#endif

    return EXIT_SUCCESS;
}

I hope it was useful not only for me :)