Re: How to streamingly read text file and display whenever updated text
On 07.10.2013 03:54, galeom...@gmail.com wrote: https://docs.google.com/file/d/0B2D69u2pweEvelh1T25ra19oZEU/edit?usp=sharing For the readers who don't bother clicking on the link above: It's a short video where the OP demonstrates how her/his usage of tail doesn't work. no matter call tail directly in python or using the script of tail all failed it seems it can not read next line In your video you use gedit to write some file and tail -f file to follow it. But tail -f will follow the file descriptor. Usually, editors like gedit won't save your changes to the original file but create a new temporary file and rename it later to the original file name after deleting the original one. Thus tail will follow an already deleted file. See also this blog post: http://tech.shantanugoel.com/2009/12/23/continuous-monitor-tail-fails.html For your example you will have to use tail -F file which will follow the file name. Alternatively you could write a simple script to simulate a continously growing file like import time for i in range(1000): with open(test.txt, a) as f: f.write(str(i) + '\n') time.sleep(1) which should work with tail -f. Bye, Andreas -- https://mail.python.org/mailman/listinfo/python-list
Re: How to streamingly read text file and display whenever updated text
I can start thread and no exception error print, and I do not know how to use tail in python script I need to cope with MySQL in python later as all file path stored in it, it is to monitor all text files -- https://mail.python.org/mailman/listinfo/python-list
Re: How to streamingly read text file and display whenever updated text
On 06/10/2013 05:06, Steven D'Aprano wrote: On Sat, 05 Oct 2013 20:17:32 -0700, galeomaga wrote: if __name__ == '__main__': try: thread.start_new_thread( readfile, (Thread-1, ) ) except: print Error: unable to start thread Why not? If you can't start a thread, you have a problem with your code. How do you expect to debug this problem? I find it amusing when novice programmers believe their main job is preventing programs from crashing. More experienced programmers realize that correct code is great, code that crashes could use improvement, but incorrect code that doesn’t crash is a horrible nightmare. -- Chris Smith http://cdsmith.wordpress.com/2011/01/09/an-old-article-i-wrote/ Roughly translated for the benefit of newbies remove the try/except :) Also note that a bare except is extremely bad practice, e.g. you can't stop rogue programs with a CTRL-C -- Roses are red, Violets are blue, Most poems rhyme, But this one doesn't. Mark Lawrence -- https://mail.python.org/mailman/listinfo/python-list
Re: How to streamingly read text file and display whenever updated text
On Sun, Oct 6, 2013 at 9:36 PM, Mark Lawrence breamore...@yahoo.co.uk wrote: Also note that a bare except is extremely bad practice, e.g. you can't stop rogue programs with a CTRL-C Or to be more accurate, a Ctrl-C will cause a jump to your except clause. Since, in this instance, that's going to emit and die, Ctrl-C will still stop the program. But yes, catching KeyboardInterrupt usually isn't your intention. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Re: How to streamingly read text file and display whenever updated text
On 06/10/2013 12:03, Chris Angelico wrote: On Sun, Oct 6, 2013 at 9:36 PM, Mark Lawrence breamore...@yahoo.co.uk wrote: Also note that a bare except is extremely bad practice, e.g. you can't stop rogue programs with a CTRL-C Or to be more accurate, a Ctrl-C will cause a jump to your except clause. Since, in this instance, that's going to emit and die, Ctrl-C will still stop the program. But yes, catching KeyboardInterrupt usually isn't your intention. ChrisA Good point, but at least this time I typed rogue correctly, unlike on the tutor mailing list :) -- Roses are red, Violets are blue, Most poems rhyme, But this one doesn't. Mark Lawrence -- https://mail.python.org/mailman/listinfo/python-list
Re: How to streamingly read text file and display whenever updated text
On Sun, Oct 6, 2013 at 10:13 PM, Mark Lawrence breamore...@yahoo.co.uk wrote: Good point, but at least this time I typed rogue correctly, unlike on the tutor mailing list :) Obligatory TVTropes link. http://tvtropes.org/pmwiki/pmwiki.php/Main/RougeAnglesOfSatin ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Re: How to streamingly read text file and display whenever updated text
On 06/10/2013 12:15, Chris Angelico wrote: On Sun, Oct 6, 2013 at 10:13 PM, Mark Lawrence breamore...@yahoo.co.uk wrote: Good point, but at least this time I typed rogue correctly, unlike on the tutor mailing list :) Obligatory TVTropes link. http://tvtropes.org/pmwiki/pmwiki.php/Main/RougeAnglesOfSatin ChrisA awful How do I know that you're not trying to send me to a rouge site? /awful -- Roses are red, Violets are blue, Most poems rhyme, But this one doesn't. Mark Lawrence -- https://mail.python.org/mailman/listinfo/python-list
Re: How to streamingly read text file and display whenever updated text
On Sun, Oct 6, 2013 at 10:31 PM, Mark Lawrence breamore...@yahoo.co.uk wrote: awful How do I know that you're not trying to send me to a rouge site? /awful I assure you, the background color is most distinctly white. They probably contract with Google for their white pixel supply: http://www.google.com.au/technology/pigeonrank.html This is, however, quite distinctly off-topic for this list... though Google does use Python extensively, and until not long ago had GvR on their payroll. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Re: How to streamingly read text file and display whenever updated text
https://docs.google.com/file/d/0B2D69u2pweEvelh1T25ra19oZEU/edit?usp=sharing no matter call tail directly in python or using the script of tail all failed it seems it can not read next line -- https://mail.python.org/mailman/listinfo/python-list
How to streamingly read text file and display whenever updated text
#!/usr/bin/python
import time
f = open('/home/martin/Downloads/a.txt')
while 1:
for line in f:
print line;
time.sleep(1);
--
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Re: How to streamingly read text file and display whenever updated text
gale...@gmail.com於 2013年10月5日星期六UTC+8下午3時38分51秒寫道：
#!/usr/bin/python
import time
f = open('/home/martin/Downloads/a.txt')
while 1:
for line in f:
print line;
time.sleep(1);
if __name__ == '__main__':
logfile = open(/home/martin/Downloads/a.txt,r);
while True:
line = logfile.readline();
if not line:
print line;
time.sleep(1);
this also failed
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Re: How to streamingly read text file and display whenever updated text
galeom...@gmail.com wrote in message
news:04ee91f9-1cbf-4364-bca3-da25aa4db...@googlegroups.com...
#!/usr/bin/python
import time
f = open('/home/martin/Downloads/a.txt')
Looks like you are on Unix so you can do this from the shell
tail -F /home/martin/Downloads/a.txt
James
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Re: How to streamingly read text file and display whenever updated text
On 05/10/2013 08:54, galeom...@gmail.com wrote: if __name__ == '__main__': logfile = open(/home/martin/Downloads/a.txt,r); while True: line = logfile.readline(); if not line: print line; time.sleep(1); this also failed Usually please state your OS and Python versions, what you expected to happen, what actually happened and the full traceback if applicable. In this case I'd hazard a guess that as you're trying to print something that evaluates to false you're not likely to see much. You can also remove the semicolons as they're simply not needed. -- Roses are red, Violets are blue, Most poems rhyme, But this one doesn't. Mark Lawrence -- https://mail.python.org/mailman/listinfo/python-list
Re: How to streamingly read text file and display whenever updated text
On 05/10/2013 09:06, James Harris wrote:
galeom...@gmail.com wrote in message
news:04ee91f9-1cbf-4364-bca3-da25aa4db...@googlegroups.com...
#!/usr/bin/python
import time
f = open('/home/martin/Downloads/a.txt')
Looks like you are on Unix so you can do this from the shell
tail -F /home/martin/Downloads/a.txt
James
Tail also works on Windows if you've unxutils installed :)
--
Roses are red,
Violets are blue,
Most poems rhyme,
But this one doesn't.
Mark Lawrence
--
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Re: How to streamingly read text file and display whenever updated text
On Sat, 05 Oct 2013 00:38:51 -0700, galeomaga wrote:
#!/usr/bin/python
import time
f = open('/home/martin/Downloads/a.txt')
while 1:
for line in f:
print line;
time.sleep(1);
So you're trying to implement tail -f?
First, check that tail -f actually works for your particular use case.
If the process writing the file uses buffered output, data will only
actually be appended to the file when the buffer is full. You can't read
what isn't there.
And if the process creates a new file with the same name, rather than
appending to the existing file, you'll still be reading the old file. You
would need to open the file again to read the new file.
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Re: How to streamingly read text file and display whenever updated text
A bit of googling found me this: http://www.linux-support.com/cms/implementation-of-tail-in-python/ import time import sys def tail_f(file): interval = 1.0 while True: where = file.tell() line = file.readline() if not line: time.sleep(interval) file.seek(where) else: yield line -- https://mail.python.org/mailman/listinfo/python-list
Re: How to streamingly read text file and display whenever updated text
On 05/10/2013 12:02, Joost Molenaar wrote: A bit of googling found me this: http://www.linux-support.com/cms/implementation-of-tail-in-python/ import time import sys def tail_f(file): interval = 1.0 while True: where = file.tell() line = file.readline() if not line: time.sleep(interval) file.seek(where) else: yield line In future could you please quote some context so that it's easier for us mere mortals to follow the thread, thanks in anticipation. -- Roses are red, Violets are blue, Most poems rhyme, But this one doesn't. Mark Lawrence -- https://mail.python.org/mailman/listinfo/python-list
Re: How to streamingly read text file and display whenever updated text
Joost Molenaar於 2013年10月5日星期六UTC+8下午7時02分05秒寫道： A bit of googling found me this: http://www.linux-support.com/cms/implementation-of-tail-in-python/ import time import sys def tail_f(file): interval = 1.0 while True: where = file.tell() line = file.readline() if not line: time.sleep(interval) file.seek(where) else: yield line After tried many times, updated text file is not shown, it only print text at the first time. #!/usr/bin/python import time import sys import thread def tail_f(filehandler): interval = 1.0 while True: try: line = filehandler.readline() where = filehandler.tell() if not line: time.sleep(interval) filehandler.seek(where) else: yield line except: print tail_f error def readfile(systemname): try: filehandler = open(/home/martin/Downloads/a.txt,r); while 1: #for line in tail_f(filehandler): # print line try: interval = 1.0 line = filehandler.readline() where = filehandler.tell() if not line: time.sleep(interval) filehandler.seek(where) print where else: print line except: print tail_f error except: print Error: readfile if __name__ == '__main__': try: thread.start_new_thread( readfile, (Thread-1, ) ) except: print Error: unable to start thread while 1: pass -- https://mail.python.org/mailman/listinfo/python-list
Re: How to streamingly read text file and display whenever updated text
On Sun, Oct 6, 2013 at 2:17 PM, galeom...@gmail.com wrote: After tried many times, updated text file is not shown, it only print text at the first time. The implementation of tail has a lot of little oddities to deal with edge cases. Why not simply use it? A while ago, I wanted to make a system that would tail a bunch of logs on a bunch of computers, and display it all to me in a single unified view. Rather than write something that opened a whole lot of files and monitored them, I simply forked a 'tail' process for each file and reacted to its stdout. It was way WAY easier than dealing with everything that could possibly happen (log rotation, etc, etc, etc) - not that it'd be impossible to deal with, but it's a waste of time reinventing this particular wheel. Build on top of what's already there, save yourself the trouble. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Re: How to streamingly read text file and display whenever updated text
On Sat, 05 Oct 2013 20:17:32 -0700, galeomaga wrote: if __name__ == '__main__': try: thread.start_new_thread( readfile, (Thread-1, ) ) except: print Error: unable to start thread Why not? If you can't start a thread, you have a problem with your code. How do you expect to debug this problem? I find it amusing when novice programmers believe their main job is preventing programs from crashing. More experienced programmers realize that correct code is great, code that crashes could use improvement, but incorrect code that doesn’t crash is a horrible nightmare. -- Chris Smith http://cdsmith.wordpress.com/2011/01/09/an-old-article-i-wrote/ -- Steven -- https://mail.python.org/mailman/listinfo/python-list
