add directory Minix
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Minix/2.0.0/wwwman/man8/init.8.html
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Minix/2.0.0/wwwman/man8/init.8.html
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<HTML>
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<HEAD>
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<TITLE>init(8)</TITLE>
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</HEAD>
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<BODY>
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<H1>init(8)</H1>
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<HR>
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<PRE>
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</PRE>
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<H2>NAME</H2><PRE>
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init - grandparent of all processes
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</PRE>
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<H2>DESCRIPTION</H2><PRE>
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The first program started by Minix is <STRONG>init</STRONG>. The actions performed by
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<STRONG>init</STRONG> can be summarized by this pseudo shell program:
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# Open 0, 1, 2.
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exec </dev/null >/dev/log 2>&1
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# Run the system initialization script.
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sh /etc/rc $bootopts
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>/etc/utmp
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echo reboot >>/usr/adm/wtmp
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while :; do
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# Wait for a process to exit, but don't always block.
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wait
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# Record logout. (Not in this dumb way, of course.)
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if "pid is in my tables" $pid
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then
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echo "logout $pid" >/etc/utmp
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echo "logout $pid" >>/usr/adm/wtmp
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fi
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# Start a new session.
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while read line type getty init
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do
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if idle $line
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then
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$init ... <$tty >$tty
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$getty <$tty >$tty 2>&1 &
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pid=$!
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"add pid to tables" $pid
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echo "login $line $pid" >/etc/utmp
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echo "login $line $pid" >>/usr/adm/wtmp
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fi
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done < /dev/ttytab
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done
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The first action of <STRONG>init</STRONG> is to run <STRONG>/etc/rc</STRONG> to initialize the system as
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described in <STRONG><A HREF="../man8/boot.8.html">boot(8)</A></STRONG>. <STRONG>Init</STRONG> then enters its main loop where it waits for
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processes to exit, and starts processes on each enabled terminal line.
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The file <STRONG>/etc/ttytab</STRONG> contains a list of terminal devices, their terminal
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types, the program to execute on them to allow one to login (usually
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<STRONG><A HREF="../man8/getty.8.html">getty(8)</A></STRONG>), and the program to execute first to initialize the line
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(usually <STRONG><A HREF="../man1/stty.1.html">stty(1)</A></STRONG>). These fields may be left out to indicate that a line
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is disabled or that initialization is not necessary. The commands are
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searched using the path <STRONG>/sbin:/bin:/usr/sbin:/usr/bin</STRONG>.
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<STRONG>Init</STRONG> accepts several signals that must be sent to process id 1. (It is
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the first process, so natually its process id is 1.) The signals are:
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<STRONG>SIGHUP</STRONG>
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When receiving a hangup signal, <STRONG>init</STRONG> will forget about errors and
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rescan <STRONG>ttytab</STRONG> for processes to execute. <STRONG>Init</STRONG> normally rescans
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<STRONG>ttytab</STRONG> each time it feels the need to respawn a process, so the
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hangup signal is only needed if a line has been shut down, or after
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a terminate signal. Note that after turning a line off you will
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have to kill the process running on that line manually, <STRONG>init</STRONG> doesn't
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do that for you.
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<STRONG>SIGTERM</STRONG>
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Normally sent by programs that halt or reboot Minix. Causes <STRONG>init</STRONG> to
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stop spawning new processes.
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<STRONG>SIGABRT</STRONG>
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Sent by the keyboard driver when the <STRONG>CTRL</STRONG>-<STRONG>ALT</STRONG>-<STRONG>DEL</STRONG> key combination is
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typed. Causes <STRONG>init</STRONG> to run the <STRONG>shutdown</STRONG> command. A second abort
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signal makes <STRONG>init</STRONG> halt the system directly with a system call. The
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keyboard driver halts the system, without a sync, after the third
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CTRL-ALT-DEL.
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<STRONG>Minix</STRONG> <STRONG>vs.</STRONG> <STRONG>Minix</STRONG>-<STRONG>vmd</STRONG>
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There are a few differences between standard Minix and Minix-vmd on how
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<STRONG>init</STRONG> is run. The <STRONG>/etc/rc</STRONG> file is executed under standard Minix with
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input connected to <STRONG>/dev/console</STRONG>, but under Minix-vmd this is still
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<STRONG>/dev/null</STRONG>. This means that under Minix-vmd processes must be reconnected
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to <STRONG>/dev/console</STRONG> with the <STRONG>intr</STRONG> program if they need user interaction.
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Minix-vmd passes the value of the <STRONG>bootopts</STRONG> boot variable to /etc/rc.
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Standard Minix does not.
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</PRE>
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<H2>FILES</H2><PRE>
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<STRONG>/etc/ttytab</STRONG> List of terminals devices.
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<STRONG>/etc/utmp</STRONG> List of currently logged in users.
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<STRONG>/usr/adm/wtmp</STRONG> Login/logout history.
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</PRE>
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<H2>SEE ALSO</H2><PRE>
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<STRONG><A HREF="../man5/ttytab.5.html">ttytab(5)</A></STRONG>, <STRONG><A HREF="../man5/utmp.5.html">utmp(5)</A></STRONG>, <STRONG><A HREF="../man8/getty.8.html">getty(8)</A></STRONG>, <STRONG><A HREF="../man1/stty.1.html">stty(1)</A></STRONG>, <STRONG><A HREF="../man8/boot.8.html">boot(8)</A></STRONG>.
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</PRE>
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<H2>AUTHOR</H2><PRE>
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Kees J. Bot (kjb@cs.vu.nl)
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</PRE>
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</BODY>
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</HTML>
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