how to read the last line of a huge file???

[Roy Smith]

In article <mailman.1353.1296119065.6505.python-list at python.org>,
 Alice Bevan–McGregor <alice at 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 :-)