Why does this Ruby code fail to write to the log file?

问题

Once the script is daemonized then the logger can't write to the file anymore. So how and when should I initialise the log?

require 'rubygems'
require 'daemons'
require 'logging'

def create_new_logger
    logger = Logging.logger['trend-analyzer']
    logger.add_appenders(
        Logging.appenders.rolling_file('./logs/trend-analyzer.log'),
        Logging.appenders.stdout
    )
    logger.level = :debug
    return logger
end

logger = create_new_logger

#this log message gets written to the log file
logger.debug Time.new 

Daemons.run_proc('ForestPress', :log_dir => '.logs', :backtrace => true) do
    running_as_daemon = true

    #this log message does NOT get written to the log file
    logger.debug Time.new

    loop do
        #this log message does NOT get written to the log file
        logger.info Time.new    
        sleep 5 
    end
end

EDIT

I notice the current path changes from where I executed the script to /. Could this be why I can't log messages?

EDIT 2

I now save the original path before becoming a daemon and then use Dir.chdir to set the path to the original path. I can then open the file directly and write to it. However the logging gem can't write to it still.

回答1:

Here is how it started working

require 'rubygems'
require 'daemons'
require 'logging'

def create_new_logger
    logger = Logging.logger['trend-analyzer']
    logger.add_appenders(
        Logging.appenders.rolling_file('./logs/trend-analyzer.log'),
        Logging.appenders.stdout
    )
    logger.level = :debug
    return logger
end

current_dir = Dir.pwd

Daemons.run_proc('ForestPress', :log_dir => '.logs', :backtrace => true) do
    Dir.chdir(current_dir)  

    logger = create_new_logger

    loop do
        puts Dir.pwd
        logger.debug Time.new   
        sleep 5 
    end
end

来源：https://stackoverflow.com/questions/10749404/why-does-this-ruby-code-fail-to-write-to-the-log-file

标签

ruby-on-rails

ruby

logging

daemon