On Thu, Aug 21, 2008 at 02:58:24PM -0700, sab wrote: > I have been working on a python script to parse a continuously growing > log file on a UNIX server.
If you weren't aware, there are already a plethora of tools which do this... You might save yourself the trouble by just using one of those. Try searching for something like "parse log file" on google or freshmeat.net or whatever... > The input is the standard in, piped in from the log file. The > application works well for the most part, but the problem is when > attempting to continuously pipe information into the application via > the tail -f command. The command line looks something like this: > > tail -f <logfile> | grep <search string> | python parse.py The pipe puts STDIN/STDOUT into "fully buffered" mode, which results in the behavior you're seeing. You can set the buffering mode of those files in your program, but unfortunately tail and grep are not your program... You might get this to work by setting stdin to non-blocking I/O in your Python program, but I don't think it will be that easy... You can get around this in a couple of ways. One is to call tail and grep from within your program, using something like os.popen()... Then set the blocking mode on the resulting files. You'll have to feed the output of one to the input of the other, then read the output of grep and parse that. Yucky. That method isn't very efficient, since Python can do everything that tail and grep are doing for you... So I'd suggest you read the file directly in your python program, and use Python's regex parsing functionality to do what you're doing with grep. As for how to actually do what tail does, I'd suggest looking at the source code for tail to see how it does what it does. But, if I were you, I'd just download something like swatch, and be done with it. :) -- Derek D. Martin http://www.pizzashack.org/ GPG Key ID: 0x81CFE75D
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