Summary of the use of logging libraries in python

Python's logging module provides a general logging system, which can be used by third-party modules or applications. The following article mainly introduces some knowledge summary about the use of logging library in python. The article gives detailed information. Sample code, friends in need can refer to it, let’s take a look below.

Preface

Recently, due to work needs, I have been writing some python scripts. It feels very low to always use print to print information, so I took the time. I have studied the logging library of python to print and record logs elegantly. I won’t go into more details below, let’s take a look at the detailed introduction.

1. Simply print the log to the screen:

Print on screen ：WARNING:root:This is warning message

By default, WARNING level logs will be printed

• DEBUG: Detailed information , debugging information.

• INFO: Confirm everything is working as expected.

• WARNING: Indicates that something unexpected has occurred, or that a problem will occur in the near future (such as 'disk full'). The software is still working normally.

• ERROR: Due to a more serious problem, the software can no longer perform some functions.

• CRITICAL: A serious error indicating that the software can no longer run.

2. Configure the log input format and method through the basicConfig function

The above code will not print the log on the screen, but will generate the log file test.log in the current directory, and the log will be printed in the log file:

2017 -10-16 Mon 10:05:17 testlogging.py[line:25] DEBUG This is debug message

2017-10-16 Mon 10:05:17 testlogging.py[line:26 ] INFO This is info message

2017-10-16 Mon 10:05:17 testlogging.py[line:27] WARNING This is warning message

• ## Parameters of the #logging.basicConfig function:

• filename: Specify the log file name

• #filemode: The same meaning as the file function, specify the log file name Open mode, 'w' or 'a'

##format: Specify the output format and content. format can output a lot of useful information, as shown in the above example:

datefmt: Specifies the time format, the same as time.strftime()
level: Sets the log level , the default is logging.WARNING
stream: Specify the output stream of the log. You can specify the output to sys.stderr, sys.stdout or a file. The default output is to sys.stderr. When stream When specified with filename at the same time, stream is ignored

3. Output the log to the screen and log file at the same time

Print on the screen:

root: INFO This is info message

root : WARNING This is warning message

printed in the file:

2017-10-16 Mon 10: 20:07 testlogging.py[line:46] DEBUG This is debug message

2017-10-16 Mon 10:20:07 testlogging.py[line:47] INFO This is info message

2017-10-16 Mon 10:20:07 testlogging.py[line:48] WARNING This is warning message

4. Configure through the configuration file Log

Log format

• ##%(filename)s file name, excluding directory

• %(pathname)s Directory name, full path

• %(funcName)s Function name

• %(levelname) s level name

• %(lineno)d line number

• ##%(module)s module name

• %(message)s Message body

• %(name)s Log module name

• %(process)d Process id

• %(processName)s process name

• %(thread)d thread id

• % (threadName)s thread name

• Test configuration file

Summary

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