27.01.2011, 15:55, "Roy Smith" <r...@panix.com>:
> In article <mailman.1353.1296119065.6505.python-l...@python.org>;,
> Alice Bevan–McGregor <al...@gothcandy.com>; wrote:
>
>> On 2011-01-26 02:59:26 -0800, Xavier Heruacles said:
>>> I have do some log processing which is usually huge. The length of each
>>> line is variable. How can I get the last line?? Don't tell me to use
>>> readlines or something like linecache...
>> This is not optimum or efficient, but it works! If you want to see
>> what's going on, use 4 instead of 4096 and 8 instead of 8192 and add a
>> print statement to the bottom of the while loop. :)
>>
>> import os
>>
>> with open('biglogfile.log', 'r') as fh:
>> fh.seek(-4096, os.SEEK_END)
>> buffer = fh.read(4096)
>>
>> # We are expecting a trailing newline.
>> while "\n" not in buffer[:-1]:
>> fh.seek(-8192, os.SEEK_CUR)
>> buffer = fh.read(4096) + buffer
>>
>> # Eliminate empty lines, they aren't useful.
>> lines = [line for line in buffer.split('\n') if line]
>> print lines[-1]
>>
>> — Alice. :)
>
> Back in the old days, if you wanted to read a file backwards, you just
> used a tape drive that had read-reverse capability :-)
>
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> http://mail.python.org/mailman/listinfo/python-list
Yeah. And if you wanted to zoom image -- you just had to go couple steps closer
to it)
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