[673b0d8] | 1 | <?xml version="1.0" encoding="ISO-8859-1"?>
|
---|
| 2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN" "http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd" [
|
---|
| 3 | <!ENTITY % general-entities SYSTEM "../general.ent">
|
---|
| 4 | %general-entities;
|
---|
| 5 | ]>
|
---|
[3be4d97] | 6 | <sect1 id="ch-scripts-usage">
|
---|
[4cfd9f0f] | 7 | <title>How work these bootscripts?</title>
|
---|
[673b0d8] | 8 | <?dbhtml filename="usage.html"?>
|
---|
| 9 |
|
---|
| 10 | <indexterm zone="ch-scripts-usage">
|
---|
| 11 | <primary sortas="a-Bootscripts">Bootscripts</primary>
|
---|
| 12 | <secondary>usage</secondary></indexterm>
|
---|
[0ad6d9a] | 13 |
|
---|
[b822811] | 14 | <para>Linux uses a special booting facility named SysVinit. It's based on a
|
---|
[673b0d8] | 15 | concept of <emphasis>run-levels</emphasis>. It can be widely different
|
---|
[51c0c603] | 16 | from one system to another, so it can't be assumed that because things
|
---|
[0ad6d9a] | 17 | worked in <insert distro name> they should work like that in LFS
|
---|
[51c0c603] | 18 | too. LFS has its own way of doing things, but it respects generally
|
---|
[b822811] | 19 | accepted standards.</para>
|
---|
[0ad6d9a] | 20 |
|
---|
[b822811] | 21 | <para>SysVinit (which we'll call <emphasis>init</emphasis> from now on) works
|
---|
[673b0d8] | 22 | using a run-levels scheme. There are 7 (from 0 to 6) run-levels
|
---|
| 23 | (actually, there are more run-levels but they are for special cases and
|
---|
[f67f5cf] | 24 | generally not used. The <command>init</command> man page describes those details), and each
|
---|
[53b5ccf] | 25 | one of those corresponds to the things the computer is supposed to do when
|
---|
[673b0d8] | 26 | it starts up. The default run-level is 3. Here are the descriptions of the
|
---|
| 27 | different run-levels as they are often implemented:</para>
|
---|
[0ad6d9a] | 28 |
|
---|
[b822811] | 29 | <literallayout>0: halt the computer
|
---|
[0ad6d9a] | 30 | 1: single-user mode
|
---|
| 31 | 2: multi-user mode without networking
|
---|
| 32 | 3: multi-user mode with networking
|
---|
| 33 | 4: reserved for customization, otherwise does the same as 3
|
---|
[3ccc1df] | 34 | 5: same as 4, it is usually used for GUI login (like X's xdm or KDE's kdm)
|
---|
[b822811] | 35 | 6: reboot the computer</literallayout>
|
---|
[0ad6d9a] | 36 |
|
---|
[673b0d8] | 37 | <para>The command used to change run-levels is <command>init
|
---|
| 38 | <runlevel></command> where <runlevel> is the target run-level. For
|
---|
[f67f5cf] | 39 | example, to reboot the computer, a user would issue the <userinput>init
|
---|
| 40 | 6</userinput> command. The <command>reboot</command> command is just an alias for
|
---|
[90e3cb3] | 41 | it, as is the <command>halt</command> command an alias for <command>init
|
---|
| 42 | 0</command>.</para>
|
---|
[0ad6d9a] | 43 |
|
---|
[f67f5cf] | 44 | <para>There are a number of directories under <filename class="directory">/etc/rc.d</filename>
|
---|
| 45 | that look like like <filename class="directory">rc?.d</filename> (where ? is the
|
---|
| 46 | number of the run-level) and <filename class="directory">rcsysinit.d</filename>
|
---|
[673b0d8] | 47 | all containing a number of symbolic links. Some begin with a K, the others begin
|
---|
[90e3cb3] | 48 | with an S, and all of them have two numbers following the initial letter. The K
|
---|
| 49 | means to stop (kill) a service, and the S means to start a service. The numbers
|
---|
| 50 | determine the order in which the scripts are run, from 00 to 99; the lower the
|
---|
[673b0d8] | 51 | number the sooner it gets executed. When init switches to another run-level, the
|
---|
[90e3cb3] | 52 | appropriate services get killed and others get started.</para>
|
---|
[d535079] | 53 |
|
---|
[f67f5cf] | 54 | <para>The real scripts are in <filename class="directory">/etc/rc.d/init.d</filename>.
|
---|
| 55 | They do all the work, and the symlinks all point to them. Killing links and starting links
|
---|
| 56 | point to the same script in <filename class="directory">/etc/rc.d/init.d</filename>.
|
---|
| 57 | That's because the scripts can be called with different parameters like
|
---|
| 58 | <parameter>start</parameter>, <parameter>stop</parameter>,
|
---|
| 59 | <parameter>restart</parameter>, <parameter>reload</parameter>,
|
---|
| 60 | <parameter>status</parameter>. When a K link is encountered, the appropriate
|
---|
| 61 | script is run with the <parameter>stop</parameter> argument. When an S link is
|
---|
| 62 | encountered, the appropriate script is run with the <parameter>start</parameter>
|
---|
| 63 | argument.</para>
|
---|
[0ad6d9a] | 64 |
|
---|
[fa914e5] | 65 | <para>There is one exception. Links that start with an S in the
|
---|
| 66 | rc0.d and rc6.d directories will not cause anything to be started. They
|
---|
[f67f5cf] | 67 | will be called with the parameter <parameter>stop</parameter> to stop
|
---|
[fa914e5] | 68 | something. The logic behind it is that when you are going to reboot or
|
---|
| 69 | halt the system, you don't want to start anything, only stop the
|
---|
| 70 | system.</para>
|
---|
| 71 |
|
---|
[b822811] | 72 | <para>These are descriptions of what the arguments make the
|
---|
| 73 | scripts do:</para>
|
---|
[b2c0c79] | 74 |
|
---|
[f67f5cf] | 75 | <variablelist>
|
---|
| 76 | <varlistentry>
|
---|
| 77 | <term><parameter>start</parameter></term>
|
---|
| 78 | <listitem><para>The service is started.</para></listitem>
|
---|
| 79 | </varlistentry>
|
---|
| 80 |
|
---|
| 81 | <varlistentry>
|
---|
| 82 | <term><parameter>stop</parameter></term>
|
---|
| 83 | <listitem><para>The service is stopped.</para></listitem>
|
---|
| 84 | </varlistentry>
|
---|
| 85 |
|
---|
| 86 | <varlistentry>
|
---|
| 87 | <term><parameter>restart</parameter></term>
|
---|
| 88 | <listitem><para>The service is stopped and then started again.</para></listitem>
|
---|
| 89 | </varlistentry>
|
---|
| 90 |
|
---|
| 91 | <varlistentry>
|
---|
| 92 | <term><parameter>reload</parameter></term>
|
---|
| 93 | <listitem><para>The configuration of the service is updated.
|
---|
[53b5ccf] | 94 | This is used after the configuration file of a service was modified, when
|
---|
[b822811] | 95 | the service doesn't need to be restarted.</para></listitem>
|
---|
[f67f5cf] | 96 | </varlistentry>
|
---|
[b2c0c79] | 97 |
|
---|
[f67f5cf] | 98 | <varlistentry>
|
---|
| 99 | <term><parameter>status</parameter></term>
|
---|
| 100 | <listitem><para>Tells if the service is running and with which PIDs.</para></listitem>
|
---|
| 101 | </varlistentry>
|
---|
| 102 | </variablelist>
|
---|
[0ad6d9a] | 103 |
|
---|
[a2cd10f] | 104 | <para>Feel free to modify the way the boot process works (after all, it's your
|
---|
| 105 | own LFS system). The files given here are just an example of how it can be
|
---|
| 106 | done in a nice way (well, what we consider nice -- you may hate it).</para>
|
---|
[0ad6d9a] | 107 |
|
---|
| 108 | </sect1>
|
---|