Answer by mykhal for How can I get a base64 encoded shaX on the cli?

Base64 encoded SHA256 hash became rather standard file checksum in OpenBSD recently.. It can be done just with adding -b option to the OpenBSD's sha256 (or sha1, sha512) command:

$ FILE=/dev/null
$ sha256 -q -b $FILE
47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU=

or:

$ cksum -q -a sha256b $FILE