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diff --git a/sag-0.6.1-www/sag-0.6.1.html/x1880.html b/sag-0.6.1-www/sag-0.6.1.html/x1880.html new file mode 100644 index 0000000..ceb8431 --- /dev/null +++ b/sag-0.6.1-www/sag-0.6.1.html/x1880.html @@ -0,0 +1,261 @@ +<!DOCTYPE HTML PUBLIC "-//Norman Walsh//DTD DocBook HTML 1.0//EN"> +<HTML +><HEAD +><TITLE +>Booting in single user mode</TITLE +><META +NAME="GENERATOR" +CONTENT="Modular DocBook HTML Stylesheet"><LINK +REL="HOME" +TITLE="The Linux System Administrators' Guide" +HREF="book1.html"><LINK +REL="UP" +TITLE="init" +HREF="c1705.html"><LINK +REL="PREVIOUS" +TITLE="Special configuration in /etc/inittab" +HREF="x1852.html"><LINK +REL="NEXT" +TITLE="Logging In And Out" +HREF="c1905.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="x1852.html" +>Prev</A +></TD +><TD +WIDTH="80%" +ALIGN="center" +VALIGN="bottom" +>Chapter 7. <B +CLASS="COMMAND" +>init</B +></TD +><TD +WIDTH="10%" +ALIGN="right" +VALIGN="bottom" +><A +HREF="c1905.html" +>Next</A +></TD +></TR +></TABLE +><HR +ALIGN="LEFT" +WIDTH="100%"></DIV +><DIV +CLASS="SECT1" +><H1 +CLASS="SECT1" +><A +NAME="AEN1880" +>Booting in single user mode</A +></H1 +><P +>An important run level is <I +CLASS="GLOSSTERM" +>single user mode</I +> (run level 1), + in which only the system administrator is using the machine + and as few system services, including logins, as possible are + running. Single user mode is necessary for a few administrative + tasks, + + <A +NAME="AEN1884" +HREF="#FTN.AEN1884" +>[1]</A +> + + such as running <B +CLASS="COMMAND" +>fsck</B +> on a + <TT +CLASS="FILENAME" +>/usr</TT +> partition, since this requires that + the partition be unmounted, and that can't happen, unless just + about all system services are killed.</P +><P +>A running system can be taken to single user mode by using + <B +CLASS="COMMAND" +>telinit</B +> to request run level 1. At bootup, + it can be entered by giving the word <TT +CLASS="LITERAL" +>single</TT +> + or <TT +CLASS="LITERAL" +>emergency</TT +> on the kernel command line: the + kernel gives the command line to <B +CLASS="COMMAND" +>init</B +> as well, + and <B +CLASS="COMMAND" +>init</B +> understands from that word that it + shouldn't use the default run level. (The kernel command line is + entered in a way that depends on how you boot the system.)</P +><P +>Booting into single user mode is sometimes necessary so + that one can run <B +CLASS="COMMAND" +>fsck</B +> by hand, before anything + mounts or otherwise touches a broken <TT +CLASS="FILENAME" +>/usr</TT +> + partition (any activity on a broken filesystem is likely to + break it more, so <B +CLASS="COMMAND" +>fsck</B +> should be run as soon + as possible).</P +><P +>The bootup scripts <B +CLASS="COMMAND" +>init</B +> runs + will automatically enter single user mode, if the automatic + <B +CLASS="COMMAND" +>fsck</B +> at bootup fails. This is an attempt to + prevent the system from using a filesystem that is so broken that + <B +CLASS="COMMAND" +>fsck</B +> can't fix it automatically. Such breakage + is relatively rare, and usually involves a broken hard disk or an + experimental kernel release, but it's good to be prepared.</P +><P +>As a security measure, a properly configured system + will ask for the root password before starting the shell in + single user mode. Otherwise, it would be simple to just enter + a suitable line to LILO to get in as root. (This will break if + <TT +CLASS="FILENAME" +>/etc/passwd</TT +> has been broken by filesystem + problems, of course, and in that case you'd better have a boot + floppy handy.)</P +></DIV +><H3 +>Notes</H3 +><TABLE +BORDER="0" +CLASS="FOOTNOTES" +WIDTH="100%" +><TR +><TD +ALIGN="LEFT" +VALIGN="TOP" +WIDTH="5%" +><A +NAME="FTN.AEN1884" +HREF="x1880.html#AEN1884" +>[1]</A +></TD +><TD +ALIGN="LEFT" +VALIGN="TOP" +WIDTH="95%" +><P +>It probably shouldn't be used for playing + <B +CLASS="COMMAND" +>nethack</B +>.</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="x1852.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="c1905.html" +>Next</A +></TD +></TR +><TR +><TD +WIDTH="33%" +ALIGN="left" +VALIGN="top" +>Special configuration in <TT +CLASS="FILENAME" +>/etc/inittab</TT +></TD +><TD +WIDTH="34%" +ALIGN="center" +VALIGN="top" +><A +HREF="c1705.html" +>Up</A +></TD +><TD +WIDTH="33%" +ALIGN="right" +VALIGN="top" +>Logging In And Out</TD +></TR +></TABLE +></DIV +></BODY +></HTML +>
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