igest algorithm and default output format:
  sysv      (equivalent to sum -s)
  bsd       (equivalent to sum -r)
  crc       (equivalent to cksum)
  md5       (equivalent to md5sum)
  sha1      (equivalent to sha1sum)
  sha224    (equivalent to sha224sum)
  sha256    (equivalent to sha256sum)
  sha384    (equivalent to sha384sum)
  sha512    (equivalent to sha512sum)
  blake2b   (equivalent to b2sum)
  sm3       (only available through cksum)

