diff options
Diffstat (limited to 'sag-0.6.1-www/Invisible/sag-0.6/node78.html')
| -rw-r--r-- | sag-0.6.1-www/Invisible/sag-0.6/node78.html | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/sag-0.6.1-www/Invisible/sag-0.6/node78.html b/sag-0.6.1-www/Invisible/sag-0.6/node78.html new file mode 100644 index 0000000..176d85e --- /dev/null +++ b/sag-0.6.1-www/Invisible/sag-0.6/node78.html @@ -0,0 +1,69 @@ +<!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>Booting in single user mode</TITLE> +<META NAME="description" CONTENT="Booting in single user mode"> +<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="tex2html1291" HREF="node79.html"><IMG WIDTH=37 HEIGHT=24 ALIGN=BOTTOM ALT="next" SRC="./next_motif.gif"></A> <A NAME="tex2html1289" HREF="node73.html"><IMG WIDTH=26 HEIGHT=24 ALIGN=BOTTOM ALT="up" SRC="./up_motif.gif"></A> <A NAME="tex2html1285" HREF="node77.html"><IMG WIDTH=63 HEIGHT=24 ALIGN=BOTTOM ALT="previous" SRC="./previous_motif.gif"></A> <A NAME="tex2html1293" HREF="node1.html"><IMG WIDTH=65 HEIGHT=24 ALIGN=BOTTOM ALT="contents" SRC="./contents_motif.gif"></A> <A NAME="tex2html1294" HREF="node114.html"><IMG WIDTH=43 HEIGHT=24 ALIGN=BOTTOM ALT="index" SRC="./index_motif.gif"></A> <BR> +<B> Next:</B> <A NAME="tex2html1292" HREF="node79.html">Logging In And Out</A> +<B>Up:</B> <A NAME="tex2html1290" HREF="node73.html">init</A> +<B> Previous:</B> <A NAME="tex2html1286" HREF="node77.html">Special configuration in /etc/inittab</A> +<BR> <P> +<H1><A NAME="SECTION00850000000000000000">Booting in single user mode</A></H1> +<P> +<A NAME="secsingleusermode"> </A> +<P> + An important run level is <b>single user mode</b> (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="tex2html38" HREF="footnode.html#2315"><IMG ALIGN=BOTTOM ALT="gif" SRC="./foot_motif.gif"></A> such as running <tt>fsck</tt><A NAME="2475"> </A> on a <tt>/usr</tt><A NAME="2477"> </A> + partition--this requires that the partition be unmounted, + and that can't happen, unless just about all system services + are killed. +<P> + A running system can be taken to single user mode by using + <tt>telinit</tt><A NAME="2479"> </A> to request run level 1. At bootup, it can be + entered by giving the word <tt>single</tt> or <tt>emergency</tt> + on the kernel command line: the kernel gives the command line + to <tt>init</tt><A NAME="2481"> </A> as well, and <tt>init</tt><A NAME="2483"> </A> 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> + Booting into single user mode is sometimes necessary so that + one can run <tt>fsck</tt><A NAME="2485"> </A> by hand, before anything mounts or + otherwise touches a broken <tt>/usr</tt><A NAME="2487"> </A> partition (any activity + on a broken filesystem is likely to break it more, so <tt>fsck</tt><A NAME="2489"> </A> + should be run as soon as possible). +<P> + The bootup scripts <tt>init</tt><A NAME="2491"> </A> runs will automatically enter single + user mode, if the automatic <tt>fsck</tt><A NAME="2493"> </A> at bootup fails. This is an + attempt to prevent the system from using a filesystem that is so + broken that <tt>fsck</tt><A NAME="2495"> </A> 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> + As a security measure, a properly configured system will ask + for the <tt>root</tt> 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 <tt>root</tt>. (This will + break if <tt>/etc/passwd</tt><A NAME="2497"> </A> has been broken by filesystem problems, + of course, and in that case you'd better have a boot floppy handy.) +<P> +<HR><A NAME="tex2html1291" HREF="node79.html"><IMG WIDTH=37 HEIGHT=24 ALIGN=BOTTOM ALT="next" SRC="./next_motif.gif"></A> <A NAME="tex2html1289" HREF="node73.html"><IMG WIDTH=26 HEIGHT=24 ALIGN=BOTTOM ALT="up" SRC="./up_motif.gif"></A> <A NAME="tex2html1285" HREF="node77.html"><IMG WIDTH=63 HEIGHT=24 ALIGN=BOTTOM ALT="previous" SRC="./previous_motif.gif"></A> <A NAME="tex2html1293" HREF="node1.html"><IMG WIDTH=65 HEIGHT=24 ALIGN=BOTTOM ALT="contents" SRC="./contents_motif.gif"></A> <A NAME="tex2html1294" HREF="node114.html"><IMG WIDTH=43 HEIGHT=24 ALIGN=BOTTOM ALT="index" SRC="./index_motif.gif"></A> <BR> +<B> Next:</B> <A NAME="tex2html1292" HREF="node79.html">Logging In And Out</A> +<B>Up:</B> <A NAME="tex2html1290" HREF="node73.html">init</A> +<B> Previous:</B> <A NAME="tex2html1286" HREF="node77.html">Special configuration in /etc/inittab</A> +<P><ADDRESS> +<I>Lars Wirzenius <BR> +Sat Nov 15 02:32:11 EET 1997</I> +</ADDRESS> +</BODY> +</HTML> |