日志一共分成5個等級，從低到高分別是：DEBUG INFO WARNING ERROR CRITICAL。
DEBUG：詳細的信息,通常只出現(xiàn)在診斷問題上
INFO：確認一切按預期運行
WARNING：一個跡象表明,一些意想不到的事情發(fā)生了,或表明一些問題在不久的將來(例如。磁盤空間低”)。這個軟件還能按預期工作。
ERROR：更嚴重的問題,軟件沒能執(zhí)行一些功能
CRITICAL：一個嚴重的錯誤,這表明程序本身可能無法繼續(xù)運行
這5個等級，也分別對應5種打日志的方法： debug 、info 、warning 、error 、critical。默認的是WARNING，當在WARNING或之上時才被跟蹤。

logging.basicConfig函數(shù)中，可以指定日志的輸出格式format，這個參數(shù)可以輸出很多有用的信息，如上例所示：
%(levelno)s: 打印日志級別的數(shù)值
%(levelname)s: 打印日志級別名稱
%(pathname)s: 打印當前執(zhí)行程序的路徑，其實就是sys.argv[0]
%(filename)s: 打印當前執(zhí)行程序名
%(funcName)s: 打印日志的當前函數(shù)
%(lineno)d: 打印日志的當前行號
%(asctime)s: 打印日志的時間
%(thread)d: 打印線程ID
%(threadName)s: 打印線程名稱
%(process)d: 打印進程ID
%(message)s: 打印日志信息
我在工作中給的常用格式在前面已經(jīng)看到了。就是：
format='%(asctime)s - %(filename)s[line:%(lineno)d] - %(levelname)s: %(message)s'
這個格式可以輸出日志的打印時間，是哪個模塊輸出的，輸出的日志級別是什么，以及輸入的日志內(nèi)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') 
執(zhí)行上面的代碼將在Console中輸出下面信息：
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') 
運行之后，打開該文件./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')