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diff --git a/sag-0.6.1-www/sag-0.6.1.html/x1752.html b/sag-0.6.1-www/sag-0.6.1.html/x1752.html new file mode 100644 index 0000000..eeabdb9 --- /dev/null +++ b/sag-0.6.1-www/sag-0.6.1.html/x1752.html @@ -0,0 +1,402 @@ +<!DOCTYPE HTML PUBLIC "-//Norman Walsh//DTD DocBook HTML 1.0//EN"> +<HTML +><HEAD +><TITLE +>Configuring init to start getty: the /etc/inittab file</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="init" +HREF="c1705.html"><LINK +REL="NEXT" +TITLE="Run levels" +HREF="x1812.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="c1705.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="x1812.html" +>Next</A +></TD +></TR +></TABLE +><HR +ALIGN="LEFT" +WIDTH="100%"></DIV +><DIV +CLASS="SECT1" +><H1 +CLASS="SECT1" +><A +NAME="AEN1752" +>Configuring <B +CLASS="COMMAND" +>init</B +> to start <B +CLASS="COMMAND" +>getty</B +>: the <TT +CLASS="FILENAME" +>/etc/inittab</TT +> file</A +></H1 +><P +>When it starts up, <B +CLASS="COMMAND" +>init</B +> reads the <TT +CLASS="FILENAME" +>/etc/inittab</TT +> + configuration file. While the system is running, it will + re-read it, if sent the HUP signal; + + <A +NAME="AEN1760" +HREF="#FTN.AEN1760" +>[1]</A +> + + this feature makes it unnecessary to boot the system to make + changes to the <B +CLASS="COMMAND" +>init</B +> configuration take + effect.</P +><P +>The <TT +CLASS="FILENAME" +>/etc/inittab</TT +> file is + a bit complicated. We'll start with the simple case + of configuring <B +CLASS="COMMAND" +>getty</B +> lines. Lines in + <TT +CLASS="FILENAME" +>/etc/inittab</TT +> consist of four colon-delimited + fields: + +<PRE +CLASS="SCREEN" +>id:runlevels:action:process</PRE +> + + The fields are described below. In addition, + <TT +CLASS="FILENAME" +>/etc/inittab</TT +> can contain empty lines, and + lines that begin with a number sign (`<TT +CLASS="LITERAL" +>#</TT +>'); + these are both ignored. + + <DIV +CLASS="GLOSSLIST" +><DL +><DT +><B +>id</B +></DT +><DD +><P +> This identifies the line in the file. For + <B +CLASS="COMMAND" +>getty</B +> lines, it specifies the terminal + it runs on (the characters after <TT +CLASS="FILENAME" +>/dev/tty</TT +> + in the device file name). For other lines, + it doesn't matter (except for length restrictions), + but it should be unique. + </P +></DD +><DT +><B +>runlevels</B +></DT +><DD +><P +> The run levels the line should be considered + for. The run levels are given as single digits, + without delimiters. (Run levels are described + in the next section.) + </P +></DD +><DT +><B +>action</B +></DT +><DD +><P +> What action should be taken by the line, e.g., + <TT +CLASS="LITERAL" +>respawn</TT +> to run the command in the + next field again, when it exits, or <TT +CLASS="LITERAL" +>once</TT +> + to run it just once. + </P +></DD +><DT +><B +>process</B +></DT +><DD +><P +> The command to run. + </P +></DD +></DL +></DIV +> + + To start a <B +CLASS="COMMAND" +>getty</B +> on the first virtual terminal + (<TT +CLASS="FILENAME" +>/dev/tty1</TT +>}), in all the normal multi-user + run levels (2-5), one would write the following line: + +<PRE +CLASS="SCREEN" +>1:2345:respawn:/sbin/getty 9600 tty1</PRE +> + + The first field says that this is the line for <TT +CLASS="FILENAME" +>/dev/tty1</TT +>. + The second field says that it applies to run levels 2, 3, 4, + and 5. The third field means that the command should be run + again, after it exits (so that one can log in, log out, and + then log in again). The last field is the command that runs + <B +CLASS="COMMAND" +>getty</B +> on the first virtual terminal. + + <A +NAME="AEN1797" +HREF="#FTN.AEN1797" +>[2]</A +> + </P +><P +>If you wanted to add terminals or dial-in modem lines to a + system, you'd add more lines to <TT +CLASS="FILENAME" +>/etc/inittab</TT +>, + one for each terminal or dial-in line. For more details, see the + manual pages <B +CLASS="COMMAND" +>init</B +>, <TT +CLASS="FILENAME" +>inittab</TT +>, + and <B +CLASS="COMMAND" +>getty</B +>.</P +><P +>If a command fails when it starts, + and <B +CLASS="COMMAND" +>init</B +> is configured to + <TT +CLASS="LITERAL" +>restart</TT +> it, it will use a lot of + system resources: <B +CLASS="COMMAND" +>init</B +> starts it, + it fails, <B +CLASS="COMMAND" +>init</B +> starts it, it fails, + <B +CLASS="COMMAND" +>init</B +> starts it, it fails, and so on, ad + infinitum. To prevent this, <B +CLASS="COMMAND" +>init</B +> will keep + track of how often it restarts a command, and if the frequency + grows to high, it will delay for five minutes before restarting + again. </P +></DIV +><H3 +>Notes</H3 +><TABLE +BORDER="0" +CLASS="FOOTNOTES" +WIDTH="100%" +><TR +><TD +ALIGN="LEFT" +VALIGN="TOP" +WIDTH="5%" +><A +NAME="FTN.AEN1760" +HREF="x1752.html#AEN1760" +>[1]</A +></TD +><TD +ALIGN="LEFT" +VALIGN="TOP" +WIDTH="95%" +><P +>Using the command <B +CLASS="COMMAND" +>kill -HUP + 1</B +> as root, for example </P +></TD +></TR +><TR +><TD +ALIGN="LEFT" +VALIGN="TOP" +WIDTH="5%" +><A +NAME="FTN.AEN1797" +HREF="x1752.html#AEN1797" +>[2]</A +></TD +><TD +ALIGN="LEFT" +VALIGN="TOP" +WIDTH="95%" +><P +>Different versions of + <B +CLASS="COMMAND" +>getty</B +> are run differently. Consult + your manual page, and make sure it is the correct + manual page.</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="c1705.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="x1812.html" +>Next</A +></TD +></TR +><TR +><TD +WIDTH="33%" +ALIGN="left" +VALIGN="top" +><B +CLASS="COMMAND" +>init</B +></TD +><TD +WIDTH="34%" +ALIGN="center" +VALIGN="top" +><A +HREF="c1705.html" +>Up</A +></TD +><TD +WIDTH="33%" +ALIGN="right" +VALIGN="top" +>Run levels</TD +></TR +></TABLE +></DIV +></BODY +></HTML +>
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