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diff --git a/usermanual/reference/class_update-rc.d.xml b/usermanual/reference/class_update-rc.d.xml new file mode 100644 index 0000000000..2da9b0bf86 --- /dev/null +++ b/usermanual/reference/class_update-rc.d.xml @@ -0,0 +1,133 @@ +<?xml version="1.0" encoding="UTF-8"?> +<section id="update-rc-d_class" xreflabel="update-rc.d class"> + <title>update-rc.d class</title> + + <para>Services which need to be started during boot need to be registered + using the update-rc.d command. These services are required to have an init + script which is installed into <command>/etc/init.d</command> that can be + used to start and stop the service.</para> + + <para>The following examples show a service being manually stopped and + started using it's init script:<screen>root@titan:/etc# /etc/init.d/syslog stop +Stopping syslogd/klogd: stopped syslogd (pid 1551). +stopped klogd (pid 1553). +done +root@titan:/etc# /etc/init.d/syslog start +Starting syslogd/klogd: done +root@titan:/etc#</screen>The update-rc.d class takes care of the following + automatically:</para> + + <orderedlist> + <listitem> + <para>Registers the service with the system during postinst so it will + be automatically started on boot;</para> + </listitem> + + <listitem> + <para>Stops the service during prerm so it will no longer be running + after being removed;</para> + </listitem> + + <listitem> + <para>Unregisters the service during prerm so there will be no attempts + to start the removed service during boot;</para> + </listitem> + + <listitem> + <para>Adds a build and run time dependency on the update-rc.d package + which it uses to register and unregister the services.</para> + </listitem> + </orderedlist> + + <para>Usage is very simple, as shown by this example from dropbear:<screen>INITSCRIPT_NAME = "dropbear" +INITSCRIPT_PARAMS = "defaults 10" + +inherit autotools update-rc.d</screen></para> + + <para>where the variables are:</para> + + <variablelist> + <varlistentry> + <term>INITSCRIPT_NAME</term> + + <listitem> + <para>The name of the init script, which the package will have + installed into /etc/init.d</para> + </listitem> + </varlistentry> + + <varlistentry> + <term>INITSCRIPT_PARAMS</term> + + <listitem> + <para>The parameters to pass to the update-rc.d call during + installation. Typically this will be the work default followed by + either single number or a pair of numbers representing the start/stop + sequence number (both are set to the same if only one number is + supplied.)</para> + </listitem> + </varlistentry> + </variablelist> + + <para>The help from update-rc.d shows show the required parameters:<screen>root@titan:/etc# update-rc.d -h +usage: update-rc.d [-n] [-f] [-r <root>] <basename> remove + update-rc.d [-n] [-r <root>] [-s] <basename> defaults [NN | sNN kNN] + update-rc.d [-n] [-r <root>] [-s] <basename> start|stop NN runlvl [runlvl] [...] . + -n: not really + -f: force + -r: alternate root path (default is /) + -s: invoke start methods if appropriate to current runlevel +root@titan:/etc#</screen>The start and stop sequence numbers need to ensure + that the the service is started at the appropriate time relative to other + services, such as waiting for any service that it depends on before starting + (networking for example). Unless the service is a system or security related + service it's better to be started as late as possible.</para> + + <section> + <title>Multiple update-rc.d packages</title> + + <para>Defining multiple init scripts within the one recipe is also + supported. Note that each init script must be in it's own package. The + following example is from the quagga recipe:<screen># Main init script starts all deamons +# Seperate init script for watchquagga +INITSCRIPT_PACKAGES = "${PN} ${PN}-watchquagga" +INITSCRIPT_NAME_${PN} = "quagga" +INITSCRIPT_PARAMS_${PN} = "defaults 15 85" +INITSCRIPT_NAME_${PN}-watchquagga = "watchquagga" +INITSCRIPT_PARAMS_${PN}-watchquagga = "defaults 90 10" + +inherit autotools update-rc.d</screen> The variables that need to be declared + are:</para> + + <variablelist> + <varlistentry> + <term>INITSCRIPT_PACKAGES</term> + + <listitem> + <para>The names of each package which includes an init + script.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term>INITSCRIPT_NAME_x</term> + + <listitem> + <para>The same meaning as INITSCRIPT_NAME, but for the package x. + This would be repeated for each package that includes an init + script.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term>INITSCRIPT_PARAMS_x</term> + + <listitem> + <para>The same meaning as INITSCRIPT_PARAMS, but for the package x. + This would be repeated for each package that includes an init + script.</para> + </listitem> + </varlistentry> + </variablelist> + </section> +</section>
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