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diff --git a/sag-0.6.1-www/sag-0.6.1.html/c1582.html b/sag-0.6.1-www/sag-0.6.1.html/c1582.html new file mode 100644 index 0000000..cd13d0e --- /dev/null +++ b/sag-0.6.1-www/sag-0.6.1.html/c1582.html @@ -0,0 +1,281 @@ +<!DOCTYPE HTML PUBLIC "-//Norman Walsh//DTD DocBook HTML 1.0//EN"> +<HTML +><HEAD +><TITLE +>Boots And Shutdowns</TITLE +><META +NAME="GENERATOR" +CONTENT="Modular DocBook HTML Stylesheet"><LINK +REL="HOME" +TITLE="The Linux System Administrators' Guide" +HREF="book1.html"><LINK +REL="PREVIOUS" +TITLE="The buffer cache" +HREF="x1551.html"><LINK +REL="NEXT" +TITLE="The boot process in closer look" +HREF="x1602.html"></HEAD +><BODY +BGCOLOR="#FFFFFF" +TEXT="#000000" +><DIV +CLASS="NAVHEADER" +><TABLE +WIDTH="100%" +BORDER="0" +CELLPADDING="0" +CELLSPACING="0" +><TR +><TH +COLSPAN="3" +ALIGN="center" +>The Linux System Administrators' Guide</TH +></TR +><TR +><TD +WIDTH="10%" +ALIGN="left" +VALIGN="bottom" +><A +HREF="x1551.html" +>Prev</A +></TD +><TD +WIDTH="80%" +ALIGN="center" +VALIGN="bottom" +></TD +><TD +WIDTH="10%" +ALIGN="right" +VALIGN="bottom" +><A +HREF="x1602.html" +>Next</A +></TD +></TR +></TABLE +><HR +ALIGN="LEFT" +WIDTH="100%"></DIV +><DIV +CLASS="CHAPTER" +><H1 +><A +NAME="BOOTS-AND-SHUTDOWNS" +>Chapter 6. Boots And Shutdowns</A +></H1 +><DIV +CLASS="TOC" +><DL +><DT +><B +>Table of Contents</B +></DT +><DT +><A +HREF="c1582.html#AEN1588" +>An overview of boots and shutdowns</A +></DT +><DT +><A +HREF="x1602.html" +>The boot process in closer look</A +></DT +><DT +><A +HREF="x1650.html" +>More about shutdowns</A +></DT +><DT +><A +HREF="x1684.html" +>Rebooting</A +></DT +><DT +><A +HREF="x1693.html" +>Single user mode</A +></DT +><DT +><A +HREF="x1697.html" +>Emergency boot floppies</A +></DT +></DL +></DIV +><BLOCKQUOTE +><P +><P +CLASS="LITERALLAYOUT" +>Start me up<br> +Ah... you've got to... you've got to<br> +Never, never never stop<br> +Start it up<br> +Ah... start it up, never, never, never<br> + You make a grown man cry,<br> + you make a grown man cry<br> +(Rolling Stones)</P +></P +></BLOCKQUOTE +><P +> This section explains what goes on when a Linux system is + brought up and taken down, and how it should be done properly. + If proper procedures are not followed, files might be corrupted + or lost.</P +><DIV +CLASS="SECT1" +><H1 +CLASS="SECT1" +><A +NAME="AEN1588" +>An overview of boots and shutdowns</A +></H1 +><P +>The act of turning on a computer system and causing its + operating system to be loaded + + <A +NAME="AEN1591" +HREF="#FTN.AEN1591" +>[1]</A +> + + is called <I +CLASS="GLOSSTERM" +>booting</I +>. The name comes from + an image of the computer pulling itself up from its bootstraps, + but the act itself slightly more realistic.</P +><P +>During bootstrapping, the computer first loads a small piece + of code called the <I +CLASS="GLOSSTERM" +>bootstrap loader</I +>, which + in turn loads and starts the operating system. The bootstrap + loader is usually stored in a fixed location on a hard disk + or a floppy. The reason for this two step process is that + the operating system is big and complicated, but the first + piece of code that the computer loads must be very small (a + few hundred bytes), to avoid making the firmware unnecessarily + complicated.</P +><P +>Different computers do the bootstrapping differently. + For PC's, the computer (its BIOS) reads in the first sector + (called the <I +CLASS="GLOSSTERM" +>boot sector</I +>) of a floppy or + hard disk. The bootstrap loader is contained within this sector. + It loads the operating system from elsewhere on the disk (or + from some other place).</P +><P +>After Linux has been loaded, it initializes the hardware and + device drivers, and then runs <B +CLASS="COMMAND" +>init</B +>. <B +CLASS="COMMAND" +>init</B +> + starts other processes to allow users to log in, and do things. + The details of this part will be discussed below.</P +><P +>In order to shut down a Linux system, first all processes + are told to terminate (this makes them close any files and + do other necessary things to keep things tidy), then filesystems + and swap areas are unmounted, and finally a message is printed + to the console that the power can be turned off. If the proper + procedure is not followed, terrible things can and will happen; + most importantly, the filesystem buffer cache might not be flushed, + which means that all data in it is lost and the filesystem on + disk is inconsistent, and therefore possibly unusable. + </P +></DIV +></DIV +><H3 +>Notes</H3 +><TABLE +BORDER="0" +CLASS="FOOTNOTES" +WIDTH="100%" +><TR +><TD +ALIGN="LEFT" +VALIGN="TOP" +WIDTH="5%" +><A +NAME="FTN.AEN1591" +HREF="c1582.html#AEN1591" +>[1]</A +></TD +><TD +ALIGN="LEFT" +VALIGN="TOP" +WIDTH="95%" +><P +>On early computers, it wasn't enough + to merely turn on the computer, you had to manually load the + operating system as well. These new-fangled thing-a-ma-jigs do + it all by themselves.</P +></TD +></TR +></TABLE +><DIV +CLASS="NAVFOOTER" +><HR +ALIGN="LEFT" +WIDTH="100%"><TABLE +WIDTH="100%" +BORDER="0" +CELLPADDING="0" +CELLSPACING="0" +><TR +><TD +WIDTH="33%" +ALIGN="left" +VALIGN="top" +><A +HREF="x1551.html" +>Prev</A +></TD +><TD +WIDTH="34%" +ALIGN="center" +VALIGN="top" +><A +HREF="book1.html" +>Home</A +></TD +><TD +WIDTH="33%" +ALIGN="right" +VALIGN="top" +><A +HREF="x1602.html" +>Next</A +></TD +></TR +><TR +><TD +WIDTH="33%" +ALIGN="left" +VALIGN="top" +>The buffer cache</TD +><TD +WIDTH="34%" +ALIGN="center" +VALIGN="top" +> </TD +><TD +WIDTH="33%" +ALIGN="right" +VALIGN="top" +>The boot process in closer look</TD +></TR +></TABLE +></DIV +></BODY +></HTML +>
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