最後更新: 2020-03-27

目錄

• basicConfig
• Log Rotating
• Basic log function(不調用 logging module)

basicConfig

logging.basicConfig([**kwargs])

Does basic configuration for the logging system

by creating a StreamHandler with a default Formatter and adding it to the root logger.

keyword arguments

• filename
• filemode
• format
• datefmt
• level
• stream

mylog.py

#!/usr/bin/env python
# coding=utf-8
# vim: sts=4:ts=4:sw=4:paste

import logging, os

def main():
    scriptpath = os.path.dirname(os.path.realpath(__file__))
    scriptname = os.path.splitext(os.path.basename(__file__))[0]
    logfile = os.path.join(scriptpath, scriptname + '.log')

    FORMAT = '%(asctime)s - %(name)s %(levelname)s: %(message)s'

#    logging.basicConfig(filename=logfile,                        
#                        level=logging.DEBUG,
#                        format=FORMAT)
    logging.basicConfig(filename=logfile)

    logging.debug('This debug message.')
    logging.info('No info message.')
    logging.warning('No warning message.')

if __name__ == '__main__':
    main()

Settings

filemode

If filename is specified, open the file in this mode. Defaults to 'a'.

level

高過或等於這個 Level 的 log 才會有 log 到.

Default: WARNING

Other Level

• logging.INFO
• logging.DEBUG

format

Default: %(levelname)s:%(name)s:%(message)s

WARNING:root:This is warning message.

  * 由於 default 係無 log 到時間, 所以最好設定 log 返它

Log Rotating

以 log size 去 rotate log

test.py

import logging, logging.handlers

def main():
    LogFile = 'log.txt'

    myLogger = logging.getLogger('MyLogger')
    myLogger.setLevel(logging.DEBUG)

    handler = logging.handlers.RotatingFileHandler(
                  LogFile, maxBytes=20, backupCount=5)

    # class logging.Formatter([fmt[, datefmt]])
    # If none is supplied, the default value of '%(message)s' is used.
    LogFormat = '%(asctime)s - %(name)s %(levelname)s: %(message)s'
    formatter = logging.Formatter(LogFormat)

    handler.setFormatter(formatter)

    myLogger.addHandler(handler)

    # Log some messages leg it over maxBytes
    for i in range(50):
        myLogger.debug('i = %d' % i)

# Test
if __name__ == '__main__':
    main()

logging.getLogger([name])

Return a logger with the specified name.

If 'name' specified, the name is typically a dot-separated hierarchical name like “a”, “a.b” or “a.b.c.d”.

%(name)s

Name of the logger used to log the call.

Output:

ls -1

log.txt
log.txt.1
...
log.txt.5

msg

2022-11-02 13:06:42,969 - MyLogger DEBUG: i = 49

轉成以時間去 log Rotating

# 將 RotatingFileHandler 換成 TimedRotatingFileHandler

    handler = logging.handlers.TimedRotatingFileHandler(
                  LogFile, when='D', backupCount=7)

located in the "logging.handlers" module

"when" to specify the type of interval

• 'S'    Seconds
• 'M'    Minutes
• 'H'    Hours
• 'D'    Days
• 'W0'-'W6'    Weekday (0=Monday)
• 'midnight'    Roll over at midnight

On rotating it also sets the filename suffix: %Y-%m-%d_%H-%M-%S

Code to check Rollover time

current_time = int(time.time())
rollover_time = handler.computeRollover(current_time)
rollover_time_midnight = handler_midnight.computeRollover(current_time)

Modify time tigger Rollover

date                   # Lab  的時間

Thu 03 Nov 2022 11:28:36 AM HKT

touch -m 202211011234 log.txt   # 修改 modify time 測試

stat log.txt          # 查看 log file 的 modify time

...
Modify: 2022-11-01 12:34:00.000000000 +0800

# After Rotate

在 3 號行 Rotate 時建立的檔案名稱後綴係 modify date (01)

log.txt.2022-11-01

Basic log function(不調用)

使用 open 及 write 完成

Code

def logf(msg):
    print msg
    import os, time
    today = time.strftime("%Y-%m-%d")
    scriptpath = os.path.dirname(os.path.realpath(__file__))
    logfile = os.path.join(scriptpath, 'log.' + today + '.txt')
    mylog = open(logfile, 'a')
    mylog.write(time.strftime("%Y-%m-%H %H:%M:%S") + ": " + msg + os.linesep)
    mylog.close
    return True