Calculate Hashes for new Files

[Ignis231]

If hashes have been calculated for a directory/folder, and when using this for verification at a later date it picks up there are some new files, is there any easy way after to calculate the hashes of the new files and incorporate that with the existing calculation?
From what I see, the only option is to either manually pick out each file, or calculate everything again from the start.

[jonelo]

Hello!

Yes, absolutely! You don't need to recalculate everything from scratch or pick out new files manually. Jacksum provides built-in options specifically designed to detect and process newly added files incrementally.

Here is a step-by-step example demonstrating how to do this:

1. Initial Hash Calculation

First, calculate the hashes for the directory (e.g., current working directory .) and save the output to .sha256:

jacksum . > .sha256

Your .sha256 file now contains the baseline hashes:

8409d74d1898bda8c6dee94cda14309f1a3cfa13c014af8a7c8885d581f03eee ./file1.txt
0c583c671b9b911489af393b9a09d7e2afd4626d65dcf1316991be115d64d8e3 ./file2.txt

2. Detect New Files

When new files (e.g., file3.txt) are added to the directory later, use --list-filter new together with --list to isolate new files and save their paths to a list:

jacksum -c .sha256 --list-filter new --list -O newfiles.list .

newfiles.list will now contain only the path to the newly detected file:

.\file3.txt

3. Calculate Hashes for New Files & Update

Finally, pass newfiles.list to Jacksum using --file-list and append (>>) the output to your existing .sha256 file:

jacksum --file-list newfiles.list >> .sha256

Result

Your .sha256 file is now updated with the newly added files, leaving existing hashes untouched:

8409d74d1898bda8c6dee94cda14309f1a3cfa13c014af8a7c8885d581f03eee ./file1.txt
0c583c671b9b911489af393b9a09d7e2afd4626d65dcf1316991be115d64d8e3 ./file2.txt
6886676d8195a1d3f6b84bee9bbd67cb2eee50708bd843b72a7e9a6a4f1bdac9 ./file3.txt

Hope this helps! Let me know if you run into any issues, please.