.\" 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 "25 February 2001" "Linux 0.99" "Linux Programmer's Manual" .SH NAME simpleinit \- process control initialization .SH SYNOPSIS .B init .RB [ single ] .RI [ script ] .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. Alternatively, the \fI/etc/inittab\fP file may be configured to run a different boot script. See below for details. .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 bootprog=file .B fileprefix=string .B PATH=search path .B INIT_PATH=search path .B "ttyline:termcap-entry:getty-command" .B finalprog=path .RE An example is as follows: .nf .RS bootprog = fileprefix = /sbin/init.d/ PATH = /usr/sbin:/usr/bin:/sbin:/bin INIT_PATH = /sbin/init.d tty1:linux:/sbin/getty 9600 tty1 tty2:linux:/sbin/getty 9600 tty2 tty3:linux:/sbin/getty 9600 tty3 tty4:linux:/sbin/getty 9600 tty4 # tty5:linux:/sbin/getty 9600 tty5 # ttyS1:dumb:/sbin/getty 9600 ttyS1 # ttyS2:dumb:/sbin/getty -m -t60 2400 ttyS2 finalprog = /sbin/rc.xdm .RE .fi Lines beginning with the .B # character are treated as comments. Please see documentation for the .BR getty (8) command that you are using, since there are several of these in the Linux community at this time. The \fBbootprog\fP value is appended to the \fBfileprefix\fP value, and the result specifies the boot programme (script) to run. If unspecified, the default is \fI/etc/rc\fP. If the boot programme is a directory, then all scripts in that directory tree are executed, in parallel. See the \fBneed\fP(8) programme for details on how to elegantly control order of execution and manage dependencies. The \fBPATH\fP value is assigned to the PATH environment variable of child processes (boot scripts). The \fBINIT_PATH\fP value is used by simpleinit(8) itself to find the location of scripts to run (if an absolute path is not given). If unset and the boot programme is a directory, that directory is used. Finally, if the script cannot be found in this path, the standard \fBPATH\fP is used. This separation allows boot scripts to invoke programmes of the same name without conflict and without needing to specify absolute paths. The \fBfinalprog\fP value specifies the path of the programme to run after all \fBgetty\fP(8) instances are spawned. At bootup, it is passed a single argument: "start". At shutdown, it is called again, this time with the argument: "stop". .SH SIGNALS \fBsimpleinit\fP(8) responds to signals in a variety of ways: .TP .B SIGHUP The \fI/etc/inittab\fP configuration file will be read again. .TP .B SIGTSTP This flips a toggle, which controls whether more processes will be spawned. .TP .B SIGINT \fBsimpleinit\fP(8) will sync a few times, and try to start \fBreboot\fP(8). Failing this, it will execute the system \fBreboot\fP(2) call. Under Linux, it is possible to configure the Ctrl-Alt-Del sequence to send a signal to the \fBinit\fP process instead of rebooting the system (\fBsimpleinit\fP(8) does this by default). .TP .B SIGQUIT The \fBreboot\fP(8) programme is executed in place of the \fBsimpleinit\fP(8) programme. This allows \fBreboot\fP(8) to cleanly remount (read-only) the root filesystem, even if the old inode for the \fBinit\fP process was unlinked. .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), .BR initctl (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 .br Richard Gooch .br Dependency support .SH AVAILABILITY The simpleinit command is part of the util-linux package and is available from ftp://ftp.kernel.org/pub/linux/utils/util-linux/.