- https://en.wikipedia.org/wiki/Secure_Hash_Algorithms
- https://en.wikipedia.org/wiki/SHA-3 – “is the latest member of the Secure Hash Algorithm family of standards”
- https://en.wikipedia.org/wiki/SHA-2
- https://en.wikipedia.org/wiki/SHA-1
There is a book at O’Reilly’s:
- https://learning.oreilly.com/library/view/classic-shell-scripting/0596005954/ – “Classic Shell Scripting”
- https://learning.oreilly.com/library/view/classic-shell-scripting/0596005954/examples_page.html – the book comes with very nice supplemental files and examples
- one of these examples is: show-identical-files.sh
- you can find it there in the “sh” subdirectory
- that script makes use of md5sum as checksum utility, but in my copy I replaced it with sha512sum resp. shake-512sum
- that checksum utility makes that script decide, whether files are “the same”
- I have been using that script “almost every day of my life” for so many years for finding identical files having deliberate different names – it groups files by their checksums computed by this checksum utility
- this script has worked for me on Unix, Linux, macosx, …, and busybox
- I have no quicker and safer way to find copies of files – … and removing unnecessary copies