login-utils/simpleinit.8

   1 .\" Copyright 1992, 1993 Rickard E. Faith (faith@cs.unc.edu)
   2 .\" May be distributed under the GNU General Public License
   3 .\" " for emacs's hilit19 mode :-)
   4 .TH SIMPLEINIT 8 "4 November 2000" "Linux 0.99" "Linux Programmer's Manual"
   5 .SH NAME
   6 simpleinit \- process control initialization
   7 .SH SYNOPSIS
   8 .B "init [ single ] [ script ]"
   9 .SH DESCRIPTION
  10 .B init
  11 is invoked as the last step in the Linux boot sequence.  If the
  12 .B single
  13 option is used, or if the file
  14 .I /etc/singleboot
  15 exists, then single user mode will be entered, by starting
  16 .IR /bin/sh .
  17 If the file
  18 .I /etc/securesingle
  19 exists, then the root password will be required to start single user mode.
  20 If the root password does not exist, or if
  21 .I /etc/passwd
  22 does not exist, the checking of the password will be skipped.
  23
  24 If the file
  25 .I /etc/TZ
  26 exists, then the contents of that file will be read, and used to set the TZ
  27 environment variable for each process started by
  28 .BR simpleinit .
  29 This "feature" is only available if it's configured at compile-time. It's
  30 not normally needed.
  31
  32 After single user mode is terminated, the
  33 .I /etc/rc
  34 file is executed, and the information in
  35 .I /etc/inittab
  36 will be used to start processes. Alternatively, the \fI/etc/inittab\fP
  37 file may be configured to run a different boot script. See below for
  38 details.
  39
  40 .SH "THE INITTAB FILE"
  41 Because of the number of init programs which are appearing in the Linux
  42 community, the documentation for the
  43 .I /etc/inittab
  44 file, which is usually found with the
  45 .BR inittab (5)
  46 man page, is presented here:
  47
  48 The format is
  49
  50 .RS
  51 .B bootprog=file
  52
  53 .B fileprefix=string
  54
  55 .B PATH=search path
  56
  57 .B INIT_PATH=search path
  58
  59 .B "ttyline:termcap-entry:getty-command"
  60
  61 .B finalprog=path
  62 .RE
  63
  64 An example is as follows:
  65
  66 .nf
  67 .RS
  68 bootprog     =
  69 fileprefix   =  /sbin/init.d/
  70 PATH         =  /usr/sbin:/usr/bin:/sbin:/bin
  71 INIT_PATH    =  /sbin/init.d
  72
  73 tty1:linux:/sbin/getty 9600 tty1
  74 tty2:linux:/sbin/getty 9600 tty2
  75 tty3:linux:/sbin/getty 9600 tty3
  76 tty4:linux:/sbin/getty 9600 tty4
  77 # tty5:linux:/sbin/getty 9600 tty5
  78 # ttyS1:dumb:/sbin/getty 9600 ttyS1
  79 # ttyS2:dumb:/sbin/getty -m -t60 2400 ttyS2
  80
  81 finalprog   = /sbin/rc.xdm
  82 .RE
  83 .fi
  84
  85 Lines beginning with the
  86 .B #
  87 character are treated as comments.  Please see documentation for the
  88 .B getty (8)
  89 command that you are using, since there are several of these in the Linux
  90 community at this time.
  91
  92 The \fBbootprog\fP value is appended to the \fBfileprefix\fP value,
  93 and the result specifies the boot programme (script) to run. If
  94 unspecified, the default is \fI/etc/rc\fP. If the boot programme is a
  95 directory, then all scripts in that directory tree are executed, in
  96 parallel. See the \fBneed\fP(8) programme for details on how to
  97 elegantly control order of execution and manage dependencies.
  98
  99 The \fBPATH\fP value is assigned to the PATH environment variable of
 100 child processes (boot scripts). The \fBINIT_PATH\fP value is used by
 101 simpleinit(8) itself to find the location of scripts to run (if an
 102 absolute path is not given). If unset the default value \fBPATH\fP is
 103 used. This separation allows boot scripts to invoke programmes of the
 104 same name without conflict and without needing to specify absolute
 105 paths.
 106
 107 The \fBfinalprog\fP value specifies the path of the programme to run
 108 after all \fBgetty\fP(8) instances are spawned. At bootup, it is
 109 passed a single argument: "start". At shutdown, it is called again,
 110 this time with the argument: "stop".
 111 .SH SIGNALS
 112 \fBsimpleinit\fP(8) responds to signals in a variety of ways:
 113 .TP
 114 .B SIGHUP
 115 The \fI/etc/inittab\fP configuration file will be read again.
 116 .TP
 117 .B SIGTSTP
 118 This flips a toggle, which controls whether more processes will be
 119 spawned.
 120 .TP
 121 .B SIGINT
 122 \fBsimpleinit\fP(8) will sync a few times, and try to start
 123 \fBreboot\fP(8). Failing this, it will execute the system
 124 \fBreboot\fP(2) call. Under Linux, it is possible to configure the
 125 Ctrl-Alt-Del sequence to send a signal to the \fBinit\fP process
 126 instead of rebooting the system (\fBsimpleinit\fP(8) does this by
 127 default).
 128 .TP
 129 .B SIGQUIT
 130 The \fBreboot\fP(8) programme is executed in place of the
 131 \fBsimpleinit\fP(8) programme. This allows \fBreboot\fP(8) to cleanly
 132 remount (read-only) the root filesystem, even if the old inode for the
 133 \fBinit\fP process was unlinked.
 134 .SH FILES
 135 .I /etc/inittab
 136 .br
 137 .I /etc/singleboot
 138 .br
 139 .I /etc/securesingle
 140 .br
 141 .I /etc/TZ
 142 .br
 143 .I /etc/passwd
 144 .br
 145 .I /etc/rc
 146 .SH "SEE ALSO"
 147 .BR inittab (5),
 148 .BR ctrlaltdel (8)
 149 .BR reboot (8),
 150 .BR termcap (5),
 151 .BR getty (8),
 152 .BR agetty (8),
 153 .BR shutdown (8),
 154 .BR need (8)
 155 .SH BUGS
 156 This program is called
 157 .B simpleinit
 158 to distinguish it from the System V compatible versions of init which are
 159 starting to appear in the Linux community.
 160 .B simpleinit
 161 should be linked to, or made identical with,
 162 .I init
 163 for correct functionality.
 164 .SH AUTHOR
 165 Peter Orbaek (poe@daimi.aau.dk)
 166 .br
 167 Version 1.20, with patches for singleuser mode by Werner Almesberger
 168 .br
 169 Richard Gooch <rgooch@atnf.csiro.au>
 170 .br
 171 Dependency support