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.\" Copyright 1992, 1993 Rickard E. Faith (faith@cs.unc.edu)
.\" May be distributed under the GNU General Public License
.\" " for emacs's hilit19 mode :-)
.TH SIMPLEINIT 8 "20 November 1993" "Linux 0.99" "Linux Programmer's Manual"
.SH NAME
simpleinit \- process control initialization
.SH SYNOPSIS
.B "init [ single ]"
.SH DESCRIPTION
.B init
is invoked as the last step in the Linux boot sequence. If the
.B single
option is used, or if the file
.I /etc/singleboot
exists, then single user mode will be entered, by starting
.IR /bin/sh .
If the file
.I /etc/securesingle
exists, then the root password will be required to start single user mode.
If the root password does not exist, or if
.I /etc/passwd
does not exist, the checking of the password will be skipped.
If the file
.I /etc/TZ
exists, then the contents of that file will be read, and used to set the TZ
environment variable for each process started by
.BR simpleinit .
This "feature" is only available if it's configured at compile-time. It's
not normally needed.
After single user mode is terminated, the
.I /etc/rc
file is executed, and the information in
.I /etc/inittab
will be used to start processes.
While
.B init
is running, several signals are trapped, with special action taken. Since
.B init
has PID 1, sending signals to the
.B init
process is easy with the
.BR kill (1)
command.
If
.B init
catches a SIGHUP (hangup) signal, the
.I /etc/inittab
will be read again.
If
.B init
catches a SIGTSTP (terminal stop) signal, no more processes will be
spawned. This is a toggle, which is reset is
.B init
catches another SIGTSTP signal.
If
.B init
catches a SIGINT (interrupt) signal,
.B init
will sync a few times, and try to start
.IR reboot .
Failing this,
.B init
will execute the system
.BR reboot (2)
call. Under Linux, it is possible to configure the Ctrl-Alt-Del sequence
to send a signal to
.B init
instead of rebooting the system.
.SH "THE INITTAB FILE"
Because of the number of init programs which are appearing in the Linux
community, the documentation for the
.I /etc/inittab
file, which is usually found with the
.BR inittab (5)
man page, is presented here:
The format is
.RS
.B "ttyline:termcap-entry:getty-command"
.RE
An example is as follows:
.nf
.RS
tty1:console:/sbin/getty 9600 tty1
tty2:console:/sbin/getty 9600 tty2
tty3:console:/sbin/getty 9600 tty3
tty4:console:/sbin/getty 9600 tty4
# tty5:console:/sbin/getty 9600 tty5
# ttyS1:dumb:/sbin/getty 9600 ttyS1
# ttyS2:dumb:/sbin/getty -m -t60 2400 ttyS2
.RE
.fi
Lines beginning with the
.B #
character are treated as comments. Please see documentation for the
.B getty (8)
command that you are using, since there are several of these in the Linux
community at this time.
.SH FILES
.I /etc/inittab
.br
.I /etc/singleboot
.br
.I /etc/securesingle
.br
.I /etc/TZ
.br
.I /etc/passwd
.br
.I /etc/rc
.SH "SEE ALSO"
.BR inittab (5),
.BR ctrlaltdel (8)
.BR reboot (8),
.BR termcap (5),
.BR getty (8),
.BR agetty (8),
.BR shutdown (8)
.SH BUGS
This program is called
.B simpleinit
to distinguish it from the System V compatible versions of init which are
starting to appear in the Linux community.
.B simpleinit
should be linked to, or made identical with,
.I init
for correct functionality.
.SH AUTHOR
Peter Orbaek (poe@daimi.aau.dk)
.br
Version 1.20, with patches for singleuser mode by Werner Almesberger
|
