Using BSD jot for generating file with random content

Quote from Using BSD jot > Most every Linux system comes with GNU seq (a utility to generate > sequences of numbers or characters). However, a much older utility – > and more flexible one – is the underutilized and unknown utility, jot. > Every BSD system, including MacOS X, will come with jot (and not with > seq). (...) > In fact, to generate a large file (5Gb in this case), try this: > >

>jot -r -c -s '' $(( 1024 * 1024 * 5 )) > file.5gb
>

When I try this out it generates a 5 MB file.

-console
$ jot -r -c -s '' $(( 1024 * 1024 * 5 )) > file.5gb
$ du -sh file.5gb
5.0M    file.5gb

What does this command exactly do? How to specify size, for example 2 GB file? Is this the recommended way to generate random content files on macOS? Do you use other tools for random content files? seq can't generate random content. Is this correct?