Getting file extensions [linux fs]

[Cameron Simpson]

On 28Mar2019 01:12, Paulo da Silva <p_s_d_a_s_i_l_v_a_ns at netcabo.pt> wrote:
>Às 23:09 de 27/03/19, Cameron Simpson escreveu:
>> On 27Mar2019 21:49, Paulo da Silva <p_s_d_a_s_i_l_v_a_ns at netcabo.pt> wrote:
>...
>> The filefrag manual entry says it works by calling one of 2 ioctls. You
>> can do that from Python with the ioctl() function in the standard fcntl
>> module. I haven't tried to do this, but the results should be basicly as
>> fast as filefrag itself.
>>
>> You'll need to decode the result the ioctl returns of course.
>>
>Thanks Cameron, I'll take a look at that.

Oh, just tangential to this.

If you were doing this ad hoc, yes calling the filefrag executable is 
very expensive. But if you are always doing a large batch of filenames 
invoking:

  filefrag lots of filenames here ...

and reading from its output can be very effective, because the expense 
of the executable is amortized over all the files - the per file cost is 
much reduced. And it saves you working out how to use the ioctls from 
Python :-)

You'll learn more from going the ioctl route though, and it gives you 
complete control if you need it.

Cheers,
Cameron Simpson <cs at cskk.id.au>