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