sha256 is a shorthand command equivalent to shasum -a 256 that returns the SHA256 digest of a given input. The information below pertains the command invoked in BSD mode, that is, the command does not end in “sum”.
sha256 [options] <files>Options
-c [checklist ...]
Provide hash(s) to check against. When sha256 is invoked with the an incorrect checksum with return SHA256 (file) = digest [ Failed ]. If the hashes match then it just spits out the calculated hash.
[-s string]
Calculate the hash of a string.
Alternative verification
There are various other ways to verify a checksum. If you want a positive output you could pipe something into the shasum command.
echo "hash file" | shasum -a 256 -cNote the two spaces in the above string, you need both or it will not work
This is probably the better way of doing this as it is a command with syntax that is more universally understood.
Further reading:
man sha256man shasum