D. Unix for Users

Unix is an operating system that manages files, directories,
programs, and users.  The basic operations are:

	login/logout
	directories and files
	    ls, mkdir, rmdir, cd, mv
	files
	    cat, more, rm, mv, cp
	programs
	i/o redir
	IDE - vi/emacs, cc, gdb
	Unix at home; Linux, BSD,