How to create a SHA256SUMS file?

Question

I can check the content of several files in a directory against checksums contained in a file named for example SHA256SUMS with sha256sum -c SHA256SUMS.

1. Is there an easy way to generate a SHA256SUMS file for all files in a directory?

2. What is the exact syntax of the SHA256SUMS file and where is the documentation (if any) of that syntax?

Answer 1

Probably not the best solution, but it worked for me:

cd directory
sha256sum -b * > SHA256SUMS

Don't know what it does if there are sub-directories in directory. For documentation see DavidPostill's answer.

Answer 2

sha256sum -b does not work recursively

Do this: find . -type f -exec sha256sum {} > checksums.txt \;

-type -f is needed to exclude directories , -exec rather than -execdir in order to get the path included in the checksums list, which facilitates automatic checking

Answer 3

Where is the documentation for sha256sums?

The GNU Core Utils documentation for md5sum can be found at:

• 6.4 md5sum: Print or check MD5 digests and
• 6.6 sha2 utilities: Print or check SHA-2 digests.

In addition:

The full documentation for sha256sum is maintained as a Texinfo manual. If info and sha256sum are properly installed at your site, the command

info coreutils 'sha256sum invocation'

should give you access to the complete manual.

Source sha256sum — compute and check SHA256 message digest