How do I split a file into multiple files on linux?

The classic UNIX environment includes a basic set of broadly available programming tools, but in the 21st century this classic environment is increasingly rare, as Unix-like operating system distributions diversify. Some include vastly more, and more modern and sophisticated, programming tools and environments, whereas others, focussing on serving a less technical audience, may disinclude even the most rudimentary programming utilities. Commands most familiar to a prior generation of UNIX users include: