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diff --git a/sag-0.6.1-www/sag-0.6.1.html/c1905.html b/sag-0.6.1-www/sag-0.6.1.html/c1905.html new file mode 100644 index 0000000..ee4b091 --- /dev/null +++ b/sag-0.6.1-www/sag-0.6.1.html/c1905.html @@ -0,0 +1,315 @@ +<!DOCTYPE HTML PUBLIC "-//Norman Walsh//DTD DocBook HTML 1.0//EN"> +<HTML +><HEAD +><TITLE +>Logging In And Out</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="Booting in single user mode" +HREF="x1880.html"><LINK +REL="NEXT" +TITLE="Logins via the network" +HREF="x1944.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="x1880.html" +>Prev</A +></TD +><TD +WIDTH="80%" +ALIGN="center" +VALIGN="bottom" +></TD +><TD +WIDTH="10%" +ALIGN="right" +VALIGN="bottom" +><A +HREF="x1944.html" +>Next</A +></TD +></TR +></TABLE +><HR +ALIGN="LEFT" +WIDTH="100%"></DIV +><DIV +CLASS="CHAPTER" +><H1 +><A +NAME="LOG-IN-AND-OUT" +>Chapter 8. Logging In And Out</A +></H1 +><DIV +CLASS="TOC" +><DL +><DT +><B +>Table of Contents</B +></DT +><DT +><A +HREF="c1905.html#AEN1911" +>Logins via terminals</A +></DT +><DT +><A +HREF="x1944.html" +>Logins via the network</A +></DT +><DT +><A +HREF="x1956.html" +>What <B +CLASS="COMMAND" +>login</B +> does</A +></DT +><DT +><A +HREF="x1988.html" +>X and xdm</A +></DT +><DT +><A +HREF="x1991.html" +>Access control</A +></DT +><DT +><A +HREF="x2008.html" +>Shell startup</A +></DT +></DL +></DIV +><BLOCKQUOTE +><P +>“I don't care to belong to a club + that accepts people like me as a member.” + (Groucho Marx)</P +></BLOCKQUOTE +><P +> This section describes what happens when a user logs + in or out. The various interactions of background processes, + log files, configuration files, and so on are described in + some detail. + </P +><DIV +CLASS="SECT1" +><H1 +CLASS="SECT1" +><A +NAME="AEN1911" +>Logins via terminals</A +></H1 +><P +><A +HREF="c1905.html#TERMINAL-LOGINS" +>Figure 8-1</A +> shows how logins happen via + terminals. First, <B +CLASS="COMMAND" +>init</B +> makes sure there is + a <B +CLASS="COMMAND" +>getty</B +> program for the terminal connection + (or console). <B +CLASS="COMMAND" +>getty</B +> listens at the terminal + and waits for the user to notify that he is ready to login in + (this usually means that the user must type something). When it + notices a user, <B +CLASS="COMMAND" +>getty</B +> outputs a welcome message + (stored in <TT +CLASS="FILENAME" +>/etc/issue</TT +>), and prompts for + the username, and finally runs the <B +CLASS="COMMAND" +>login</B +> + program. <B +CLASS="COMMAND" +>login</B +> gets the username as a + parameter, and prompts the user for the password. If these + match, <B +CLASS="COMMAND" +>login</B +> starts the shell configured + for the user; else it just exits and terminates the process + (perhaps after giving the user another chance at entering the + username and password). <B +CLASS="COMMAND" +>init</B +> notices that + the process terminated, and starts a new <B +CLASS="COMMAND" +>getty</B +> + for the terminal. + </P +><DIV +CLASS="FIGURE" +><P +><B +><A +NAME="TERMINAL-LOGINS" +>Figure 8-1. Logins via terminals: the interaction of <B +CLASS="COMMAND" +>init</B +>, <B +CLASS="COMMAND" +>getty</B +>, <B +CLASS="COMMAND" +>login</B +>, and the shell.</A +></B +></P +><P +><IMG +SRC="logins-via-terminals.gif"></P +></DIV +><P +> Note that the only new process is the + one created by <B +CLASS="COMMAND" +>init</B +> (using the + <TT +CLASS="FUNCTION" +>fork</TT +> system call); <B +CLASS="COMMAND" +>getty</B +> + and <B +CLASS="COMMAND" +>login</B +> only replace the program running in + the process (using the <TT +CLASS="FUNCTION" +>exec</TT +> system call). + </P +><P +> A separate program, for noticing the user, is needed + for serial lines, since it can be (and traditionally was) + complicated to notice when a terminal becomes active. + <B +CLASS="COMMAND" +>getty</B +> also adapts to the speed and other + settings of the connection, which is important especially for + dial-in connections, where these parameters may change from call + to call. </P +><P +> There are several versions of <B +CLASS="COMMAND" +>getty</B +> + and <B +CLASS="COMMAND" +>init</B +> in use, all with their good and + bad points. It is a good idea to learn about the versions on + your system, and also about the other versions (you could use the + Linux Software Map to search them). If you don't have dial-in's, + you probably don't have to worry about <B +CLASS="COMMAND" +>getty</B +>, + but <B +CLASS="COMMAND" +>init</B +> is still important. </P +></DIV +></DIV +><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="x1880.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="x1944.html" +>Next</A +></TD +></TR +><TR +><TD +WIDTH="33%" +ALIGN="left" +VALIGN="top" +>Booting in single user mode</TD +><TD +WIDTH="34%" +ALIGN="center" +VALIGN="top" +> </TD +><TD +WIDTH="33%" +ALIGN="right" +VALIGN="top" +>Logins via the network</TD +></TR +></TABLE +></DIV +></BODY +></HTML +>
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