Python Print To Error Console
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Sys.stderr Python Example
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File=sys.stderr Invalid Syntax
Sign up How to print to stderr in Python? up vote 676 down vote favorite 103 I've come across at least three ways to print to stderr: import sys print >> sys.stderr, 'spam' sys.stderr.write('spam\n') from __future__ import print_function print('spam', file=sys.stderr) It seems to contradict zen of Python #13 †, so what's the preferred way to do it? Are there any advantages or disadvantages
Python Redirect Stderr
to one way or the other? † There should be one — and preferably only one — obvious way to do it. python printing stderr zen share|improve this question edited Jun 21 '15 at 22:27 Peter Mortensen 10.3k1369107 asked Apr 7 '11 at 0:59 wim 77k24152241 27 The first way listed is one of the many things removed in Python 3. The consensus seems to be that the >> syntax was ugly anyway, and since print is now a function, the syntax would never work. –Steve Howard Aug 5 '11 at 21:50 14 Here's another one to add to your list: os.write(2, "spam\n") –Will Hardy Jul 10 '13 at 10:54 4 I use: sys.exit('Error:
in your code, you might put in print statements/print() calls to display the value of variables. Don’t do this. Use the Python logging module. The logging is better than printing because: print(input()) It's easy to put a timestamp in each message, which is very handy.
Print Hello World End O In Python
You can have different levels of urgency for messages, and filter out less urgent messages. When you want to later lambda cannot have return statement find/remove log messages, you won't get them confused for real print() calls. If you just print to a log file, it's easy to leave the log function calls in and just ignore them http://stackoverflow.com/questions/5574702/how-to-print-to-stderr-in-python when you don't need them. (You don't have to constantly pull out print() calls.) Using print is for coders with too much time on their hands. Use logging instead. Also, learn to use the Python debugger to debug bugs and Pylint to prevent bugs and make your code readable. To print log messages to the screen, copy and paste this code: import logging
logging.basicConfig(level=logging.DEBUG, format='%(asctime)s - http://inventwithpython.com/blog/2012/04/06/stop-using-print-for-debugging-a-5-minute-quickstart-guide-to-pythons-logging-module/ %(levelname)s - %(message)s')
logging.debug('This is a log message.') To write log messages to a file, you can copy and paste this code (the only difference is in bold): import logging
logging.basicConfig(filename='log_filename.txt', level=logging.DEBUG, format='%(asctime)s - %(levelname)s - %(message)s')
logging.debug('This is a log message.') Later runs of the program will append to the end of the log file, rather than overwrite the file. To log messages to a file AND printed to the screen, copy and paste the following: import logging
logger = logging.getLogger()
logger.setLevel(logging.DEBUG)
formatter = logging.Formatter('%(asctime)s - %(levelname)s - %(message)s')
fh = logging.FileHandler('log_filename.txt')
fh.setLevel(logging.DEBUG)
fh.setFormatter(formatter)
logger.addHandler(fh)
ch = logging.StreamHandler()
ch.setLevel(logging.DEBUG)
ch.setFormatter(formatter)
logger.addHandler(ch)
logger.debug('This is a test log message.') Make sure that the logger variable is global, so that you can use it in functions. (You don't need the "global logger" at the top of the function, because the logger variable is only read, not modified.) The different levels of logging, from highest urgency to lowest urgency, are: CRITICAL ERROR WARNING INFO DEBUG The setLevel() call sets the minimum log level of messages it actually logs. So if you fh.setLevel(logging.ERROR), then WARNING, INFO, and DEBUG log messages will n
a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and http://blender.stackexchange.com/questions/6173/where-does-console-output-go policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or posting ads with us Blender Questions Tags Users Badges https://aykutakin.wordpress.com/2013/08/06/logging-to-console-and-file-in-python/ Unanswered Ask Question _ Blender Stack Exchange is a question and answer site for people who use Blender to create 3D graphics, animations, or games. Join them; it only in python takes a minute: Sign up Here's how it works: Anybody can ask a question Anybody can answer The best answers are voted up and rise to the top Where does console output go up vote 13 down vote favorite 3 I'm trying to debug a Python script by placing 'print( "foo=" + foo )' statements in my code. But python print to where does the output appear? It doesn't appear on the Python Console, and it doesn't appear on the area that appears when you drag the lower edge of the infobar downwards (what is the name for this area? My script errors show up in red here.) python scripting share|improve this question asked Jan 11 '14 at 0:19 P i 1,22121030 1 I believe that area is called the info panel, but I might be wrong. –gandalf3♦ Jan 11 '14 at 1:45 Info Editor (wiki.blender.org/index.php/Doc:2.6/Manual/Interface#Overview) –Greg Zaal Aug 31 '14 at 13:16 1 Possible duplicate of How to view python error messages? –Billy S Jul 24 at 0:16 add a comment| 3 Answers 3 active oldest votes up vote 19 down vote accepted It's printed to the system console. If it's not opened, go to Window > Toggle System Console. Note that this option is only available on Windows. On other OS, start Blender from a terminal. See here: http://wiki.blender.org/index.php/Doc:2.6/Manual/Interface/Window_system/Console_window You may also use this script: Is there anyway to mak
Console and File InPython Posted on August 6, 2013 by Aykut Akin Python has a great integrated logging mechanism for developers. You don't have to make complicated stuffs to activate logger and you can easily log to file or console with separating different kinds of log levels. In this writing, I will create a basic initialization method and use it to log my main program. More complicated implications are up to you. First, I want to give some basic concepts of logger for python. Logger has a 5 different level in python. These are: debug info warning error critical Every output place is controlled by handlers. For example, if you want to console output, you need to define console related handler. After that, you can handle logging level or logging format via that handler. Now, I will give you a basic example code for logging. My file structure will be like below: There is loggerinitializer.py file: import logging import os.path def initialize_logger(output_dir): logger = logging.getLogger() logger.setLevel(logging.DEBUG) # create console handler and set level to info handler = logging.StreamHandler() handler.setLevel(logging.INFO) formatter = logging.Formatter("%(levelname)s - %(message)s") handler.setFormatter(formatter) logger.addHandler(handler) # create error file handler and set level to error handler = logging.FileHandler(os.path.join(output_dir, "error.log"),"w", encoding=None, delay="true") handler.setLevel(logging.ERROR) formatter = logging.Formatter("%(levelname)s - %(message)s") handler.setFormatter(formatter) logger.addHandler(handler) # create debug file handler and set level to debug handler = logging.FileHandler(os.path.join(output_dir, "all.log"),"w") handler.setLevel(logging.DEBUG) formatter = logging.Formatter("%(levelname)s - %(message)s") handler.setFormatter(formatter) logger.addHandler(handler) Line 5-6: Get main logger to add new specifications. Then set global log level to debug. Line 9-13: In this area I add console logging mechanism to logger. In first line I get StreamHandler() and this means console for me. Then I said I only want output for INFO messages or higher level like errors or critical messages. For example Debug me