[Feature] Piecewise and timing options

[simsong]

Converted from SourceForge issue 3571311, submitted by chudel

Good day,

I am interested in using hashdeep in some research capacities and could benefit from the following enhancement request(s):

• Piecewise, I would like to specify the number of Pieceiwse pieces (or range) to compute. For example "-p 1024b -P 2" would print only the second piecewise piece of size 1024bytes. -P 1-4 might print just the first 4 pieces, -P 1 just the first piece and -P 0 prints all the pieces (redundant way to achieve existing functionality)
• time - I would like to also see the time it takes to calculate each hash as part of the output.

Thanks,

[simsong]

Submitted by jessekornblum

These functions would be awkward to implement in hashdeep, and in general, can already be accomplished using other commands. For example, to get the first 1-4 lines of the output, use the 'head' command:

$ hashdeep [FILES] | head -n 4

For the timing, use the time command:

$ time hashdeep [FILES]

[simsong]

Submitted by chudel

I respect your answer. I will check-out the code and make the changes. While the capabilities are available in separte pieces (using as you mention the 'head' function and the 'time' function in unix), if I only wanted the first piece of every file in the system, it would be a challenge to calculate the time it takes just to compute the first piecewise hash. Also, it would be very inefficient because I would wind up hashing all the pieces when I only wanted the first.

Let me know if you would like to consider taking the changes once made.

Thanks & Cheers - this is some great software!

[simsong]

Submitted by jessekornblum

If you only want to hash the first part of each file, you can do that, for example, using the dd command:

$ dd if=FILENAME bs=BYTES count=1 | hashdeep

[chudel]

FYI - I made a fork to do this, calculating only the initial hash value of size xxx bytes of each file. Option for this is -P (capital P).