https://www.liaoxuefeng.com/wiki/001374738125095c955c1e6d8bb493182103fac9270762a000/00138683229901532c40b749184441dbd428d2e0f8aa50e000

https://www.cnblogs.com/nancyzhu/p/8551506.html

https://www.cnblogs.com/deeper/p/7404190.html

https://blog.csdn.net/sollor525/article/details/79152526

1. Print to console

import logging
 logging.debug('debug information')
logging.warning('Only this will output.)')
logging.info('info information')

Since the default level is warning, all warning-only information is output to the console.

WARNING:root: Only this will output.

Use logging.basicConfig() to print information to the console

import logging
logging.basicConfig(format='%(asctime)s - %(pathname)s[line:%(lineno)d] - %(levelname)s: %(message)s',
                    level=logging.DEBUG)
logging.debug('debug information')
logging.info('info information')
logging.warning('warning information')
logging.error('error information')
logging.critical('critial information')

Since the value of level in logging.basicConfig() is set to logging.DEBUG, all debug, info, warning, error, critical logs are printed to the console.

So if level = logging.info() is set, the debug information is not output to the console.

2. Save log to file using logging.basicConfig()

logging.basicConfig(level=logging.DEBUG, #log level for console printing)
                    filename='new.log',
                    filemode='a', ##mode, w and a are write modes, each time the log is rewritten, overwriting the previous log
                    #a is the append mode, which is the default if not written
                    format=
                    '%(asctime)s - %(pathname)s[line:%(lineno)d] - %(levelname)s: %(message)s'
                    #Log format
                    )

If you set filename and filemode in logging.basicConfig(), only the log is saved to a file and not to the console.

Four components of logging log module

Before introducing the log stream processing flow of the logging module, let's first introduce the four components of the logging module:

If logging.basicConfig()Set up filename and filemode，Then only save log To a file, not to the console.

Write to Log my.log, Unable to print out

#https://www.cnblogs.com/nancyzhu/p/8551506.html



#https://blog.csdn.net/sollor525/article/details/79152526



#--coding:UTF-8--




import logging



log_format='%(asctime)s - %(pathname)s[line:%(lineno)d] - %(levelname)s: %(message)s'




date_format = "%m/%d/%Y %H:%M:%S %p"




filemode='a'   ##a is the append mode, which defaults to the append mode; w is the write mode, which overwrites previous logs 




logging.basicConfig(filename='my.log', filemode='a', level=logging.INFO, format=log_format)  #Format-Sets the print output format, a is the append mode, default if not written, is the append mode




 



logging.debug('debug')



logging.info('info')



logging.warning('warning')



logging.error('error')



logging.critical('critial')

Write to Log all.log, And can print out

#https://www.cnblogs.com/nancyzhu/p/8551506.html



 




import logging




from logging import handlers



 



class Logger(object):



    level_relations = {



        'debug':logging.DEBUG,



        'info':logging.INFO,



        'warning':logging.WARNING,



        'error':logging.ERROR,



        'crit':logging.CRITICAL



    }#Log Level Relationship Mapping




 



    def __init__(self,filename,level='info',when='D',backCount=3,





				 fmt='%(asctime)s - %(pathname)s[line:%(lineno)d] - %(levelname)s: %(message)s'):



        self.logger = logging.getLogger(filename)



        format_str = logging.Formatter(fmt)#Format Log




        self.logger.setLevel(self.level_relations.get(level))#Set Log Level




        sh = logging.StreamHandler()#Output to screen




        sh.setFormatter(format_str) #Format screen display




        th = handlers.TimedRotatingFileHandler(filename=filename,when=when,backupCount=backCount,encoding='utf-8')#Write to File#Processor that automatically generates files at specified intervals




        #Instantiate TimedRotatingFileHandler




        #Interval is the time interval, backupCount is the number of backup files, if more than this number, will be automatically deleted, when is the unit of time interval, there are several units:




        # W Every week ( interval==0 Time Representation Monday)          # midnight every morning




 



        th.setFormatter(format_str)  #Format Writes in Files




        self.logger.addHandler(sh)   #Add objects to logger




        self.logger.addHandler(th)




if __name__ == '__main__':



    log = Logger(filename='all.log',level='debug')     #filename='all.log'    level='debug'




    log.logger.debug('debug')



    log.logger.info('info')



    log.logger.warning('warning')



    log.logger.error('Report errors')



    log.logger.critical('serious')



    #Logger('error.log', level='error').logger.error('error')

Write to Log log1.log, And can print out

#https://www.cnblogs.com/deeper/p/7404190.html	




import logging



logger = logging.getLogger(__name__)



logger.setLevel(level = logging.INFO)



handler = logging.FileHandler("log1.txt")



handler.setLevel(logging.INFO)



formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')



handler.setFormatter(formatter)



 



console = logging.StreamHandler()



console.setLevel(logging.INFO)



 



logger.addHandler(handler)



logger.addHandler(console)



 



logger.info("Start")



logger.debug("debug")



logger.warning("fail")



logger.info("Finish")