openwrt-archive/docs/init-scripts.tex

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} enable}
or \texttt{/etc/init.d/\textit{name} disable}. 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. 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}