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diff --git a/sag-0.6.1-www/Invisible/sag-0.6/node74.html b/sag-0.6.1-www/Invisible/sag-0.6/node74.html new file mode 100644 index 0000000..7ed9108 --- /dev/null +++ b/sag-0.6.1-www/Invisible/sag-0.6/node74.html @@ -0,0 +1,74 @@ +<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN"> +<!--Converted with LaTeX2HTML 96.1-h (September 30, 1996) by Nikos Drakos (nikos@cbl.leeds.ac.uk), CBLU, University of Leeds --> +<HTML> +<HEAD> +<TITLE>init comes first</TITLE> +<META NAME="description" CONTENT="init comes first"> +<META NAME="keywords" CONTENT="sag"> +<META NAME="resource-type" CONTENT="document"> +<META NAME="distribution" CONTENT="global"> +<LINK REL=STYLESHEET HREF="sag.css"> +</HEAD> +<BODY LANG="EN" > + <A NAME="tex2html1245" HREF="node75.html"><IMG WIDTH=37 HEIGHT=24 ALIGN=BOTTOM ALT="next" SRC="./next_motif.gif"></A> <A NAME="tex2html1243" HREF="node73.html"><IMG WIDTH=26 HEIGHT=24 ALIGN=BOTTOM ALT="up" SRC="./up_motif.gif"></A> <A NAME="tex2html1237" HREF="node73.html"><IMG WIDTH=63 HEIGHT=24 ALIGN=BOTTOM ALT="previous" SRC="./previous_motif.gif"></A> <A NAME="tex2html1247" HREF="node1.html"><IMG WIDTH=65 HEIGHT=24 ALIGN=BOTTOM ALT="contents" SRC="./contents_motif.gif"></A> <A NAME="tex2html1248" HREF="node114.html"><IMG WIDTH=43 HEIGHT=24 ALIGN=BOTTOM ALT="index" SRC="./index_motif.gif"></A> <BR> +<B> Next:</B> <A NAME="tex2html1246" HREF="node75.html">Configuring init to start </A> +<B>Up:</B> <A NAME="tex2html1244" HREF="node73.html">init</A> +<B> Previous:</B> <A NAME="tex2html1238" HREF="node73.html">init</A> +<BR> <P> +<A NAME="2327"> </A><H1><A NAME="SECTION00810000000000000000"><tt>init</tt> comes first</A></H1> +<P> + <tt>init</tt><A NAME="2329"> </A> is one of those programs that are absolutely essential + to the operation of a Linux system, but that you still can mostly + ignore. A good Linux distribution will come with a configuration + for <tt>init</tt><A NAME="2331"> </A> that will work for most systems, and on these + systems there is nothing you need to do about <tt>init</tt><A NAME="2333"> </A>. Usually, + you only need to worry about <tt>init</tt><A NAME="2335"> </A> if you hook up serial + terminals, dial-in (not dial-out) modems, or if you want to change + the default run level. +<P> + When the kernel has started itself (has been loaded into memory, + has started running, and has initialized all device drivers and + data structures and such), it finishes its own part of the boot + process by starting a user level program, <tt>init</tt><A NAME="2337"> </A>. Thus, + <tt>init</tt><A NAME="2339"> </A> is always the first process (its process number is + always 1). +<P> + The kernel looks for <tt>init</tt><A NAME="2341"> </A> in a few locations that have + been historically used for it, but the proper location for it + (on a Linux system) is <tt>/sbin/init</tt><A NAME="2343"> </A>. If the kernel can't + find <tt>init</tt><A NAME="2345"> </A>, it tries to run <tt>/bin/sh</tt><A NAME="2347"> </A>, and if that + also fails, the startup of the system fails. +<P> + When <tt>init</tt><A NAME="2349"> </A> starts, it finishes the boot process by doing + a number of administrative tasks, such as checking filesystems, + cleaning up <tt>/tmp</tt><A NAME="2351"> </A>, starting various services, and starting + a <tt>getty</tt><A NAME="2353"> </A> for each terminal and virtual console where users + should be able to log in (see chapter <A HREF="node79.html#chlogins">8</A>). +<P> + After the system is properly up, <tt>init</tt><A NAME="2355"> </A> restarts + <tt>getty</tt><A NAME="2357"> </A> for each terminal after a user has logged out (so + that the next user can log in). <tt>init</tt><A NAME="2359"> </A> also adopts orphan + processes: when a process starts a child process and dies before + its child, the child immediately becomes a child of <tt>init</tt><A NAME="2361"> </A>. + This is important for various technical reasons, but it is good + to know it, since it makes it easier to understand process lists + and process tree graphs.<A NAME="tex2html32" HREF="footnode.html#2308"><IMG ALIGN=BOTTOM ALT="gif" SRC="./foot_motif.gif"></A> +<P> + There are a few variants of <tt>init</tt><A NAME="2367"> </A> available. Most Linux + distributions use <tt>sysvinit</tt><A NAME="2369"> </A> (written by Miquel van + Smoorenburg), which is based on the System V <tt>init</tt><A NAME="2371"> </A> design. + The BSD versions of Unix have a different <tt>init</tt><A NAME="2373"> </A>. The primary + difference is run levels: System V has them, BSD does not + (at least traditionally). This difference is not essential. + We'll look at <tt>sysvinit</tt><A NAME="2375"> </A> only. +<P> +<HR><A NAME="tex2html1245" HREF="node75.html"><IMG WIDTH=37 HEIGHT=24 ALIGN=BOTTOM ALT="next" SRC="./next_motif.gif"></A> <A NAME="tex2html1243" HREF="node73.html"><IMG WIDTH=26 HEIGHT=24 ALIGN=BOTTOM ALT="up" SRC="./up_motif.gif"></A> <A NAME="tex2html1237" HREF="node73.html"><IMG WIDTH=63 HEIGHT=24 ALIGN=BOTTOM ALT="previous" SRC="./previous_motif.gif"></A> <A NAME="tex2html1247" HREF="node1.html"><IMG WIDTH=65 HEIGHT=24 ALIGN=BOTTOM ALT="contents" SRC="./contents_motif.gif"></A> <A NAME="tex2html1248" HREF="node114.html"><IMG WIDTH=43 HEIGHT=24 ALIGN=BOTTOM ALT="index" SRC="./index_motif.gif"></A> <BR> +<B> Next:</B> <A NAME="tex2html1246" HREF="node75.html">Configuring init to start </A> +<B>Up:</B> <A NAME="tex2html1244" HREF="node73.html">init</A> +<B> Previous:</B> <A NAME="tex2html1238" HREF="node73.html">init</A> +<P><ADDRESS> +<I>Lars Wirzenius <BR> +Sat Nov 15 02:32:11 EET 1997</I> +</ADDRESS> +</BODY> +</HTML> |