My python script buffers the output and it causes delays before the text appiers on the console

Linux bash is exelent tool for every day use. It allows you to combine tools and chain them toggethr to achieve remarkable results. As one of my favorite I use this one when testing:

$ python some_script.py | tee log.$(date +%s).txt 

Problem

The problem is that althoug I get all the output on the console it appers to be bufffered and I can't monitor the logs in live when my script runs. An example code can be seen below.
 

	# Try to execute the script in two different modes to see the difference
	#
	# $ python log.py | tee log
	# <noting for a long time>
	#
	# $ python -u log.py | tee log
	# my log message 0
	#
	import time
	DEBUG = 0
	def log(message):
	print message
	def debug(message):
	if DEBUG>0:
	log("debug[%2d]: " % DEBUG + message)
	if __name__ == '__main__':
	for i in range(0,1000):
	log("my log message " + str(i))
	time.sleep(1)
	debug("my debug message" + str(i))

view raw example_debug.py hosted with ❤ by GitHub

Solution

You have to tell python to stop buffering the data sent the the stream you are using (stdin, stdout, stderr). On on the way I found convenient is by using the command line '-u' options.

References

• http://stackoverflow.com/questions/107705/python-output-buffering
• http://stackoverflow.com/questions/3515757/python-print-statements-being-buffered-with-output-redirection
• http://www.pixelbeat.org/programming/stdio_buffering/