Linux uses a special booting facility named SysVinit that is
based on a concept of run-levels. It can be quite different from
one system to another, so it cannot be assumed that because
things worked in one particular Linux distribution, they should
work the same in LFS too. LFS has its own way of doing things,
but it respects generally accepted standards. SysVinit (which
will be referred to as “init” from now on) works using a run-
levels scheme. There are seven (numbered 0 to 6) run-levels
(actually, there are more run-levels, but they are for special
cases and are generally not used. See init(8) for more details),
and each one of those corresponds to the actions the computer is
supposed to perform when it starts up. The default run-level is
3. Here are the descriptions of the different run-levels as they
are implemented: 0: halt the computer 1: single-user mode 2:
multi-user mode without networking 3: multi-user mode with
networking 4: reserved for customization, otherwise does the
same as 3 5: same as 4, i