日志一共分成5个等级，从低到高分别是：DEBUG INFO WARNING ERROR CRITICAL。
DEBUG：详细的信息,通常只出现在诊断问题上
INFO：确认一切按预期运行
WARNING：一个迹象表明,一些意想不到的事情发生了,或表明一些问题在不久的将来(例如。磁盘空间低”)。这个软件还能按预期工作。
ERROR：更严重的问题,软件没能执行一些功能
CRITICAL：一个严重的错误,这表明程序本身可能无法继续运行
这5个等级，也分别对应5种打日志的方法： debug 、info 、warning 、error 、critical。默认的是WARNING，当在WARNING或之上时才被跟踪。

logging.basicConfig函数中，可以指定日志的输出格式format，这个参数可以输出很多有用的信息，如上例所示：
%(levelno)s: 打印日志级别的数值
%(levelname)s: 打印日志级别名称
%(pathname)s: 打印当前执行程序的路径，其实就是sys.argv[0]
%(filename)s: 打印当前执行程序名
%(funcName)s: 打印日志的当前函数
%(lineno)d: 打印日志的当前行号
%(asctime)s: 打印日志的时间
%(thread)d: 打印线程ID
%(threadName)s: 打印线程名称
%(process)d: 打印进程ID
%(message)s: 打印日志信息
我在工作中给的常用格式在前面已经看到了。就是：
format='%(asctime)s - %(filename)s[line:%(lineno)d] - %(levelname)s: %(message)s'
这个格式可以输出日志的打印时间，是哪个模块输出的，输出的日志级别是什么，以及输入的日志内容。

import logging 

logging.basicConfig(level=logging.WARNING, 
          format='%(asctime)s - %(filename)s[line:%(lineno)d] - %(levelname)s: %(message)s') 
# use logging 
logging.info('this is a loggging info message') 
logging.debug('this is a loggging debug message') 
logging.warning('this is loggging a warning message') 
logging.error('this is an loggging error message') 
logging.critical('this is a loggging critical message') 
执行上面的代码将在Console中输出下面信息：
2017-03-16 16:58:11,266 - a.py[line:10] - WARNING: this is loggging a warning message
2017-03-16 16:58:11,266 - a.py[line:11] - ERROR: this is an loggging error message
2017-03-16 16:58:11,266 - a.py[line:12] - CRITICAL: this is a loggging critical message

import logging 

logging.basicConfig(level=logging.WARNING, 
          filename='./log/log.txt', 
          filemode='w', 
          format='%(asctime)s - %(filename)s[line:%(lineno)d] - %(levelname)s: %(message)s') 
# use logging 
logging.info('this is a loggging info message') 
logging.debug('this is a loggging debug message') 
logging.warning('this is loggging a warning message') 
logging.error('this is an loggging error message') 
logging.critical('this is a loggging critical message') 
运行之后，打开该文件./log/log.txt，效果如下：
2015-05-21 17:30:20,282 - log.py[line:12] - WARNING: this is loggging a warning message
2015-05-21 17:30:20,282 - log.py[line:13] - ERROR: this is an loggging error message
2015-05-21 17:30:20,282 - log.py[line:14] - CRITICAL: this is a loggging critical message

#config.conf
###############################################
[loggers]
keys=root,example01,example02

[logger_root]
level=DEBUG
handlers=hand01,hand02

[logger_example01]
handlers=hand01,hand02
qualname=example01
propagate=0

[logger_example02]
handlers=hand01,hand03
qualname=example02
propagate=0

###############################################
[handlers]
keys=hand01,hand02,hand03

[handler_hand01]
class=StreamHandler
level=INFO
formatter=form02
args=(sys.stderr,)

[handler_hand02]
class=FileHandler
level=NOTSET
formatter=form01
args=('myapp.log', 'a')

[handler_hand03]
class=handlers.RotatingFileHandler
level=INFO
formatter=form02
args=('myapp.log', 'a', 10*1024*1024, 5)

###############################################
[formatters]
keys=form01,form02
[formatter_form01]
format=%(asctime)s %(filename)s[line:%(lineno)d] %(levelname)s %(message)s
datefmt=%a, %d %b %Y %H:%M:%S
[formatter_form02]
format=%(name)-12s: %(levelname)-8s %(message)s
datefmt=

import logging
import logging.config

logging.config.fileConfig("/home/razerware/configscript/config.conf")
logger = logging.getLogger("example01")
logger2 = logging.getLogger("example02")
logger.debug('This is debug message')
logger.info('This is info message')
logger.warning('This is warning message')

logger2.debug('This is debug message')
logger2.info('This is info message')
logger2.warning('This is warning message')