Python log output and python log

Python log output and python log

Import logging

Logger = logging. getLogger () # generate a log object, which is the name of the log object. It can be left blank. If the name is not specified, it is root.

Handler = logging. FileHandler ("Log_test.txt") # generate a handler (processor ),

# The code below formatter specifies the log output format

Fmt = '% (asctime) s-% (filename) s: % (lineno) s-% (name) s-% (message) s'

Formatter = logging. Formatter (fmt) # instantiate formatter

Handler. setFormatter (formatter) # Add formatter for handler

 

Logger. addHandler (handler)

Logger. setLevel (logging. NOTSET) # Set the log output level

Logger. error ("This is an error message") # If the output setting is smaller than the level, no output will be made. Therefore, the setting here should be higher than setLevel.

Logger.info ("This is an info message ")

Logger. critical ("This is a critical message ")

 

Python can generate many handler, which is responsible for sending the log information created by logger to the specified destination, and sending different Handler types to different destinations. FileHandler writes the log information to the file; StreamHandler outputs the log information to the console; SMTPHandler sends the log information in the form of an email; and SocketHandler sends the log information using TCP Socket; mongoramhandler sends log information using UDP datagram

 

Formatter format

Attribute name	Format	Description
Name	% (Name) s	Log name
Asctime	% (Asctime) s	Readable time. The default format is '2017-07-08 16:49:45, 123456'. The value is millisecond after a comma.
Filename	% (Filename) s	File Name, part of pathname
Pathname	% (Pathname) s	File full path name
FuncName	% (FuncName) s	Method names corresponding to multiple call logs
Levelname	% (Levelname) s	Log Level
Levelno	% (Levelno) s	Digital Log Level
Lineno	% (Lineno) d	Number of lines in the source code of the recorded log
Module	% (Module) s	Module name
Msecs	% (Msecs) d	Millisecond in time
Process	% (Process) d	Process ID
ProcessName	% (ProcessName) s	Process name
Thread	% (Thread) d	Thread ID
ThreadName	% (ThreadName) s	Thread name
RelativeCreated	% (RelativeCreated) d	Relative time of log creation, in milliseconds

 

 

The log level relationship is: CRITICAL> ERROR> WARNING> INFO> DEBUG> NOTSET. You can also define the log level by yourself.