add some documentation for the init scripts

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@5140 3c298f89-4303-0410-b956-a3cf2f4a3e73

docs/init-scripts.tex

@@ -0,0 +1,61 @@
+Because OpenWrt uses its own init script system, all init scripts must be installed
+as \texttt{/etc/init.d/\textit{name}} use \texttt{/etc/rc.common} as a wrapper.
+
+Example: \texttt{/etc/init.d/httpd}
+
+\begin{Verbatim}
+#!/bin/sh /etc/rc.common
+# Copyright (C) 2006 OpenWrt.org
+
+START=50
+start() {
+    [ -d /www ] && httpd -p 80 -h /www -r OpenWrt
+}
+
+stop() {
+    killall httpd
+}
+\end{Verbatim}
+
+as you can see, the script does not actually parse the command line arguments itself.
+This is done by the wrapper script \texttt{/etc/rc.common}.
+
+\texttt{start()} and \texttt{stop()} are the basic functions, which almost any init
+script should provide. \texttt{start()} is called when the user runs \texttt{/etc/init.d/httpd start}
+or (if the script is enabled and does not override this behavior) at system boot time.
+
+Enabling and disabling init scripts is done by running \texttt{/etc/init.d/\textit{name} start} 
+or \texttt{/etc/init.d/\textit{name} stop}. This creates or removes symbolic links to the
+init script in \texttt{/etc/rc.d}, which is processed by \texttt{/etc/init.d/rcS} at boot time.
+
+The order in which these scripts are run is defined in the variable \texttt{START} in the init
+script, which is optional and defaults to \texttt{50}. Changing it requires running 
+\texttt{/etc/init.d/\textit{name} enable} again.
+
+You can also override these standard init script functions:
+\begin{itemize}
+	\item \texttt{boot()} \\
+		Commands to be run at boot time. Defaults to \texttt{start()}
+		
+	\item \texttt{restart()} \\
+		Restart your service. Defaults to \texttt{stop(); start()}
+	
+	\item \texttt{reload()} \\
+		Reload the configuration files for your service. Defaults to \texttt{restart()}
+
+\end{itemize}
+
+You can also add custom commands by creating the appropriate functions and referencing them
+in the \texttt{EXTRA\_COMMANDS} variable. Helptext is added in \texttt{EXTRA\_HELP}.
+
+Example:
+
+\begin{Verbatim}
+status() {
+    # print the status info
+}
+
+EXTRA_COMMANDS="status"
+EXTRA_HELP="        status  Print the status of the service"
+\end{Verbatim}
+

docs/openwrt.tex

@@ -25,6 +25,7 @@
 
 \subsection{Hotplug}
 \subsection{Init scripts}
+\include{init-scripts}
 \subsection{Network scripts}
 \include{network-scripts}