Compute a checksum with System V-compatible algorithm and 512-byte blocks

Compute checksums and the number of blocks for a file.
A predecessor to the more modern `cksum`.
More information: <https://www.gnu.org/software/coreutils/sum>.
Trick copyright: tl;dr; <https://github.com/tldr-pages/tldr>

sum --sysv {{file}}

click the source code to copy install sum on any operating system with command-not-found.com