% The Mastodon init program
% Jessica L. Parsons <orc@pell.portland.or.us>
% Wed Jan 16 07:29:26 PST 2008

#Init for Mastodon Linux

**Init** is the mother of all processes -- it is the first 
process a UNIX(r) system starts up and it manages all runlevel
changes and essential programs (`getty`, and, on some systems
`xdm`.)   It reads the file `/etc/inittab` to find out
what processes to run and when to run them.

The [Mastodon](/Mastodon/) init setup
is a service based one, where each init script starts a particular
system service and refers to the other services by name.  **init**
maintains an incore registry of active services -- each init script
queries this database to see if its prerequisites are running and
starts them if they aren't.

**Init** puts the system into one of 4 different runlevels:

=(**`S`**)ingle-user=
    This conventionally is just a single
    shell, with all filesystems except the root filesystem unmounted.
=(**`M`**)ultiuser=
    This is the system as it normally functions,
    with all services running and accessable to users.
=(**`R`**)ebooting=
    **init** goes into this runlevel when it's
    stopping all services and preparing to do a software reboot of
    the computer.
=(**`H`**)alting=
    **init** goes into this runlevel when it's
    stopping all services and preparing to halt the computer.  It's
    much like the **`r`** runlevel, except that it will go back into
    multiuser mode if you press a key at the \*\*system halted\*\*
    prompt.

The **init** package comes with the following programs:

 *  **`init`**
 *  **`shutdown`** halts or reboots the system by either telling
    `init` to change to the appropriate runlevel or by just blindly
    taking the machine down.
 *  **`wall`** writes a message to everyone on the system.
 *  **`mesg`** sets your terminal to allow or deny messages.
 *  **`showreg`** shows all the processes currently registered.
 *  **`halt`** (and **`reboot`**) halt (and reboot) the system,
    either by telling `init` to go to runlevel **`h`** (**`r`**) or by
    bringing down the system by themselves.
 *  **`need`** queries the **`init`** service registry for a process,
    and if not found, starts that process and registers it.   Need
    assumes that your system has the init scripts in the directories
    `/etc/rc.d/rc.*` and `/etc/rc.d/init.d`.
 *  **`runlevel`** displays the current runlevel.
 *  **`telinit`** tells **`init`** what runlevel you wish to change
    to.  It is also used to tell **init** to reread `/etc/inittab`
    after it's been changed.
 *  **`check`** checks `/etc/inittab` for validity.

##Source Code

=[version 1.1](init-1.1.tar.gz)=
    With manpages! It also changes `shutdown` to not ask for a message
    unless you give the `-m` flag and checks in a fix to stop it
    from getting confused about how long to wait before entering
    _OhMyGodProcessesWon'tStopTimeToPanicNow!_ mode during
    shutdown.
=[version 1.0](init-1.0.tar.gz)=
    The first release of init.  It uses a fifo to pass commands
    into the init process, except for runlevel changes which are
    passed by signal.  A few manpages were written for this release,
    but not very many.