path: root/src/admin/7_config.xml

<?xml version="1.0" encoding="utf-8"?>
<chapter label="7" id="config">
    <title>System Configuration</title>
    <highlights><para>In this chapter, we will overview the main configuration files present in the Adélie Linux system.</para></highlights>
    <section>
        <title>Introduction</title>
        <para>This chapter will cover the main configuration files that are commonly referenced in the daily administration of Adélie Linux systems.  This list is not exhaustive, and is not a list of every configuration file in the Adélie Linux system.  Some configuration files are only present when a specific system option (such as audio, graphics, or networking) is installed.</para>
        <para>Each section in this chapter has the following subsections:</para>
        <itemizedlist>
            <listitem><para><firstterm>Purpose</firstterm>, which describes for what the configuration file is responsible;</para></listitem>
            <listitem><para><firstterm>Syntax</firstterm>, which describes the high-level syntax type used by the configuration file; and finally,</para></listitem>
            <listitem><para>either <firstterm>Detailed Information</firstterm> for information on configuration files specific to the Adélie Linux system, or <firstterm>External References</firstterm> for either manual pages or online links to more information about configuration files from packages.</para></listitem>
        </itemizedlist>
    </section>
    <section>
        <title><filename>/etc/abuild.conf</filename>: Package build configuration</title>
        <section role="NotInToc">
            <title>Purpose</title>
            <para>The <filename>/etc/abuild.conf</filename> file determines how packages are built on the system.  This file sets global parameters; <filename>$HOME/.abuild.conf</filename> can override any setting from the <filename>/etc/abuild.conf</filename> on a per-user basis.</para>
        </section>
        <section role="NotInToc">
            <title>Syntax</title>
            <para>Shell script.  Comments may appear anywhere, and start with '<literal>#</literal>'.  Variables are in uppercase and follow shell quote syntax.</para>
        </section>
        <section role="NotInToc">
            <title>External References</title>
            <para>Please reference the Adélie Linux Developer's Handbook for more information about how to configure <filename>/etc/abuild.conf</filename>.  If you are reading this documentation on your local computer, the Developer's Handbook may be found in the <filename class="directory">devel/</filename> directory at the same level as this handbook's <filename class="directory">admin/</filename> directory.  If you are reading this documentation online via the Internet, you may find the newest version of the Developer's Handbook at the <ulink url="https://help.adelielinux.org/html/devel/">Adélie Linux Help Centre</ulink>.</para>
        </section>
    </section>
    <section id="e-a-r">
        <title><filename>/etc/apk/repositories</filename>: Package repository configuration</title>
        <section role="NotInToc">
            <title>Purpose</title>
            <para>The <filename>/etc/apk/repositories</filename> file determines the repositories used by the APK package manager for obtaining packages.  As noted in <xref linkend="apk_repos" />, package repositories contain packages that you may install and uninstall on an Adélie Linux system.</para>
        </section>
        <section role="NotInToc">
            <title>Syntax</title>
            <para>A single URL or file location per line.  Comments are not allowed.</para>
        </section>
        <section role="NotInToc">
            <title>Detailed Information</title>
            <para>A repository must be either a URL (beginning with <literal>https://</literal>) or an absolute path (such as <filename class="directory">/srv/packages</filename>).  The computer's architecture (as specified in <filename>/etc/apk/arch</filename>) will be appened to the path &ndash; for example, specifying the path <filename class="directory">/srv/packages/repository</filename> on a <literal>ppc64</literal> computer will result in the packages and <filename>APKINDEX</filename> being retrieved from <filename class="directory">/srv/packages/repository/ppc64</filename>.</para>
            <para>If a repository is invalid, does not have a recognised signing key, or does not exist, it will not be considered by APK.  Depending on the parameters passed to APK and the operation being performed, this may be a warning or a fatal error.</para>
        </section>
    </section>
    <section>
        <title><filename>/etc/asound.conf</filename>: System audio configuration</title>
        <section role="NotInToc">
            <title>Purpose</title>
            <para>The <filename>/etc/asound.conf</filename> file determines the behaviour audio hardware present on the system.  It can be used to select default bitrates, configure hardware options, and determine which sound card is the default/primary in a system with multiple sound cards present.  This file is only significant on systems that have audio options installed.</para>
        </section>
        <section role="NotInToc">
            <title>Syntax</title>
            <para>Sections are blocks, with the name followed by curly braces (<literal>{</literal> and <literal>}</literal>) where the options are specified for that section.  See the external reference for more information.</para>
        </section>
        <section role="NotInToc">
            <title>External References</title>
            <para>For more information on configuring system audio hardware, refer to <ulink url="https://www.alsa-project.org/main/index.php/Asoundrc">the official documentation at the ALSA Project Web site</ulink> on the Internet.  <!-- If you do not have an internet connection, XXX TODO help!  does anyone know if asoundrc(5) exists?  can't find it in any of our packages --></para>
        </section>
    </section>
    <section>
        <title><filename>/etc/bash/bashrc</filename>: Bash shell startup configuration</title>
        <section role="NotInToc">
            <title>Purpose</title>
            <para>The <filename>/etc/bash/bashrc</filename> file is sourced by the Bash shell when it starts up.  This can set shell options and configure the shell environment for you.  It is highly recommended to create your own scripts inside <filename class="directory">/etc/profile.d</filename> instead of modifying <filename>/etc/bash/bashrc</filename>, since it may change during upgrades to the Bash package.  This file is only present on systems that have the Bash shell installed.</para>
        </section>
        <section role="NotInToc">
            <title>Syntax</title>
            <para>Shell script.</para>
        </section>
        <section role="NotInToc">
            <title>External References</title>
            <para>For more information, refer to the bash(1) manpage.  If this manpage is not present on your system, it may be installed via the <package>bash-doc</package> package.</para>
        </section>
    </section>
    <section>
        <title><filename>/etc/conf.d/alsa</filename>: Mixer level configuration</title>
        <section role="NotInToc">
            <title>Purpose</title>
            <para>The <filename>/etc/conf.d/alsa</filename> file determines if volume levels are preserved across system restarts when the <literal>alsasound</literal> service is enabled.  This file is only significant on systems that have audio options installed.</para>
        </section>
        <section role="NotInToc">
            <title>Syntax</title>
            <para>Shell script.  Variables are in uppercase.</para>
        </section>
        <section role="NotInToc">
            <title>External References</title>
            <para>For more information, refer to the comments in the <filename>/etc/conf.d/alsa</filename> file.</para>
        </section>
    </section>
    <section>
        <title><filename>/etc/conf.d/bootmisc</filename>: Boot behaviour configuration</title>
        <section role="NotInToc">
            <title>Purpose</title>
            <para>The <filename>/etc/conf.d/bootmisc</filename> file determines certain characteristics about boot behaviour.  It controls whether the <filename class="directory">/tmp</filename> directory is cleaned, and whether <literal>dmesg</literal> is written to <filename>/var/log/dmesg</filename> on boot.  It also controls if the previous <filename>/var/log/dmesg</filename> is renamed to <filename>/var/log/dmesg.old</filename> for later comparison.</para>
        </section>
        <section role="NotInToc">
            <title>Syntax</title>
            <para>Shell script.  Variables are in lowercase.  Booleans may be set as <literal>YES</literal> or <literal>NO</literal>.</para>
        </section>
        <section role="NotInToc">
            <title>Detailed Information</title>
            <para>The following variables are configurable in the <filename>/etc/conf.d/bootmisc</filename> file:</para>
            <table frame="none">
                <title>Configurable variables in <filename>/etc/conf.d/bootmisc</filename></title>
                <tgroup cols="3" align="left" colsep="1" rowsep="1">
                <thead>
                    <row>
                        <entry>Variable</entry>
                        <entry>Meaning</entry>
                        <entry>Default</entry>
                    </row>
                </thead>
                <tbody>
                    <row>
                        <entry><varname>clean_tmp_dirs</varname></entry>
                        <entry>Directories to be treated as temporary, to be cleaned when <varname>wipe_tmp</varname> is <literal>YES</literal>.</entry>
                        <entry><literal><filename class="directory">/tmp</filename></literal></entry>
                    </row>
                    <row>
                        <entry><varname>wipe_tmp</varname></entry>
                        <entry>Determines if the directories listed in <varname>clean_tmp_dirs</varname> are completely erased on system boot.</entry>
                        <entry><literal>YES</literal></entry>
                    </row>
                    <row>
                        <entry><varname>log_dmesg</varname></entry>
                        <entry>Determines if the contents of the <literal>dmesg</literal> kernel message buffer are written to <filename>/var/log/dmesg</filename> on system boot.</entry>
                        <entry><literal>YES</literal></entry>
                    </row>
                    <row>
                        <entry><varname>previous_dmesg</varname></entry>
                        <entry>When <varname>log_dmesg</varname> is <literal>YES</literal>, determines if <filename>/var/log/dmesg</filename> is moved to <filename>/var/log/dmesg.old</filename> on system boot instead of being overwritten.</entry>
                        <entry><literal>NO</literal></entry>
                    </row>
                </tbody>
                </tgroup>
            </table>
        </section>
    </section>
    <section>
        <title><filename>/etc/conf.d/devfs</filename>: <filename class="directory">/dev</filename> configuration</title>
        <section role="NotInToc">
            <title>Purpose</title>
            <para>The <filename>/etc/conf.d/devfs</filename> file determines if the system attempts to mount <filename class="directory">/dev</filename> during system initialisation.  Most systems will not need this configuration modified.</para>
        </section>
        <section role="NotInToc">
            <title>Syntax</title>
            <para>Shell script.  Variables are in lowercase.  Booleans may be set as <literal>YES</literal> or <literal>NO</literal>.</para>
        </section>
        <section role="NotInToc">
            <title>Detailed Information</title>
            <para>The <varname>skip_mount_dev</varname> variable may be set to <literal>YES</literal> to prevent the system from automatically attempting to mount <filename class="directory">/dev</filename> during system initialisation.  The default setting of the <varname>skip_mount_dev</varname> variable is <literal>NO</literal>.</para>
        </section>
    </section>
    <section>
        <title><filename>/etc/conf.d/dmesg</filename>: <literal>dmesg</literal> configuration</title>
        <section role="NotInToc">
            <title>Purpose</title>
            <para>The <filename>/etc/conf.d/dmesg</filename> file determines the behaviour of the <literal>dmesg</literal> kernel log buffer.</para>
        </section>
        <section role="NotInToc">
            <title>Syntax</title>
            <para>Shell script.  Variables are in lowercase.</para>
        </section>
        <section role="NotInToc">
            <title>Detailed Information</title>
            <para>The <varname>dmesg_level</varname> controls the "console level", or the severity required for a message to be printed to the system console.  The default value is <literal>1</literal>, which corresponds to the <literal>emerg</literal> log level.  This prevents all messages from being written to the console except kernel panics.</para>
        </section>
    </section>
    <section>
        <title><filename>/etc/conf.d/fsck</filename>: Startup file system check configuration</title>
        <section role="NotInToc">
            <title>Purpose</title>
            <para>The <filename>/etc/conf.d/fsck</filename> file determines the behaviour of the <command>fsck</command> (file system check) command during system initialisation.  It is important to note that the configuration in the <filename>/etc/conf.d/fsck</filename> does not control manual invocations of the <command>fsck</command> command.</para>
        </section>
        <section role="NotInToc">
            <title>Syntax</title>
            <para>Shell script.  Variables are in lowercase.  Booleans may be set as <literal>YES</literal> or <literal>NO</literal>.</para>
        </section>
        <section role="NotInToc">
            <title>Detailed Information</title>
            <para>The following variables are configurable in the <filename>/etc/conf.d/fsck</filename> file:</para>
            <table frame="none">
                <title>Configurable variables in <filename>/etc/conf.d/fsck</filename></title>
                <tgroup cols="3" align="left" colsep="1" rowsep="1">
                <thead>
                    <row>
                        <entry>Variable</entry>
                        <entry>Meaning</entry>
                        <entry>Default</entry>
                    </row>
                </thead>
                <tbody>
                    <row>
                        <entry><varname>fsck_args</varname></entry>
                        <entry>Determines the command line arguments passed for routine <command>fsck</command>.</entry>
                        <entry><literal>-p -C0 -T -A</literal></entry>
                    </row>
                    <row>
                        <entry><varname>fsck_passno</varname></entry>
                        <entry>Determines which file systems will be checked by routine <command>fsck</command> during system initialisation by their "pass number" in <filename>/etc/fstab</filename>.</entry>
                        <entry><literal></literal></entry>
                    </row>
                    <row>
                        <entry><varname>fsck_on_battery</varname></entry>
                        <entry>Determines if <command>fsck</command> will be run on startup if the computer is running on battery power.</entry>
                        <entry><literal>YES</literal></entry>
                    </row>
                    <row>
                        <entry><varname>fsck_shutdown</varname></entry>
                        <entry>Determines if routine <command>fsck</command> should be performed during system shutdown, instead of during system initialisation.</entry>
                        <entry><literal>NO</literal></entry>
                    </row>
                    <row>
                        <entry><varname>fsck_abort_on_errors</varname></entry>
                        <entry>Determines if system initialisation should be halted if <command>fsck</command> finds errors.</entry>
                        <entry><literal>YES</literal></entry>
                    </row>
                </tbody>
                </tgroup>
            </table>
        </section>
    </section>
    <section>
        <title><filename>/etc/conf.d/gettys</filename>: System console configuration</title>
        <section role="NotInToc">
            <title>Purpose</title>
            <para>The <filename>/etc/conf.d/gettys</filename> file determines the parameters and behaviour of virtual terminals (VTs) and serial consoles on the system.</para>
        </section>
        <section role="NotInToc">
            <title>Syntax</title>
            <para>Shell script.  Variables are mixed-case.</para>
        </section>
        <section role="NotInToc">
            <title>Detailed Information</title>
            <para>The <filename>/etc/conf.d/gettys</filename> file defines the variable <varname>GETTYS</varname>.  The <varname>GETTYS</varname> variable controls the devices that the system will search for, on which to run VTs.  Each device is separated by a space ("<literal> </literal>").  The default is "<literal>tty1 tty2 tty3 tty4 tty5 tty6 hvc0</literal>", which will start a VT on each virtual TTY 1-6, and also start a VT on <literal>hvc0</literal> if it exists.  The <literal>hvc0</literal> device is present on most IBM servers, and also most Xen guests.</para>
            <para>For every device specified in <varname>GETTYS</varname>, the following two variables can be used for further device configuration:</para>
            <variablelist>
                <title>Configuration variables in <filename>/etc/conf.d/gettys</filename></title>
                <varlistentry>
                    <term><varname>GETTYS_<replaceable>term</replaceable>_OPTIONS</varname></term>
                    <listitem><para>Determines the options passed to <command>agetty</command> for this VT.  For more information, refer to the <command>agetty</command> manual, found in the <package>util-linux-doc</package> package.</para></listitem>
                </varlistentry>
                <varlistentry>
                    <term><varname>GETTYS_<replaceable>term</replaceable>_BAUDRATE</varname></term>
                    <listitem><para>Determines the baud rate of the specified serial line.  This option is only effective on devices that act as serial lines.</para></listitem>
                </varlistentry>
            </variablelist>
            <important><title>Important</title><para>Changes to this file will not take effect until the system is restarted.</para></important>
        </section>
    </section>
    <section>
        <title><filename>/etc/conf.d/hwclock</filename>: System time configuration</title>
        <section role="NotInToc">
            <title>Purpose</title>
            <para>The <filename>/etc/conf.d/hwclock</filename> file determines how the system will use the hardware real time clock (RTC), if present.</para>
        </section>
        <section role="NotInToc">
            <title>Syntax</title>
            <para>Shell script.  Variables are in lowercase.  Booleans may be set as <literal>YES</literal> or <literal>NO</literal>.</para>
        </section>
        <section role="NotInToc">
            <title>Detailed Information</title>
            <para></para>
        </section>
    </section>
    <section>
        <title><filename>/etc/conf.d/keymaps</filename>: Keyboard layout configuration</title>
        <section role="NotInToc">
            <title>Purpose</title>
            <para>The <filename>/etc/conf.d/keymaps</filename> file determines certain behaviours of the keyboard connected to the system console.</para>
        </section>
        <section role="NotInToc">
            <title>Syntax</title>
            <para>Shell script.  Variables are in lowercase.  Booleans may be set as <literal>YES</literal> or <literal>NO</literal>.</para>
        </section>
        <section role="NotInToc">
            <title>Detailed Information</title>
            <para>The <filename>/etc/conf.d/keymaps</filename> file </para>
        </section>
    </section>
    <section>
        <title><filename>/etc/conf.d/modules</filename>: Kernel module configuration</title>
        <section role="NotInToc">
            <title>Purpose</title>
            <para>The <filename>/etc/conf.d/</filename> file </para>
        </section>
        <section role="NotInToc">
            <title>Syntax</title>
            <para>Shell script.  Variables are in </para>
        </section>
        <section role="NotInToc">
            <title>Detailed Information</title>
            <para></para>
        </section>
    </section>
    <section>
        <title><filename>/etc/conf.d/net</filename>: Network configuration</title>
        <section role="NotInToc">
            <title>Purpose</title>
            <para>The <filename>/etc/conf.d/net</filename> file determines the configuration of the network adaptor(s) installed in the system.</para>
        </section>
        <section role="NotInToc">
            <title>Syntax</title>
            <para>Shell script style.</para>
        </section>
        <section role="NotInToc">
            <title>Detailed Information</title>
            <para>Refer to <xref linkend="networking" /> for information on configuring networks using the Adélie Linux system.</para>
        </section>
    </section>
    <section>
        <title><filename>/etc/conf.d/netmount</filename>: Network file system configuration</title>
        <section role="NotInToc">
            <title>Purpose</title>
            <para>The <filename>/etc/conf.d/</filename> file </para>
        </section>
        <section role="NotInToc">
            <title>Syntax</title>
            <para>Shell script.  Variables are in </para>
        </section>
        <section role="NotInToc">
            <title>Detailed Information</title>
            <para></para>
        </section>
    </section>
    <section>
        <title><filename>/etc/conf.d/swap</filename>: Network swap file configuration</title>
        <section role="NotInToc">
            <title>Purpose</title>
            <para>The <filename>/etc/conf.d/</filename> file </para>
        </section>
        <section role="NotInToc">
            <title>Syntax</title>
            <para>Shell script.  Variables are in </para>
        </section>
        <section role="NotInToc">
            <title>Detailed Information</title>
            <para></para>
        </section>
    </section>
    <section>
        <title><filename>/etc/conf.d/udev-trigger</filename>: Hardware hot-plug configuration</title>
        <section role="NotInToc">
            <title>Purpose</title>
            <para>The <filename>/etc/conf.d/</filename> file </para>
        </section>
        <section role="NotInToc">
            <title>Syntax</title>
            <para>Shell script.  Variables are in </para>
        </section>
        <section role="NotInToc">
            <title>Detailed Information</title>
            <para></para>
        </section>
    </section>
    <section>
        <title><filename>/etc/conf.d/urandom</filename>: Random number configuration</title>
        <section role="NotInToc">
            <title>Purpose</title>
            <para>The <filename>/etc/conf.d/</filename> file </para>
        </section>
        <section role="NotInToc">
            <title>Syntax</title>
            <para>Shell script.  Variables are in </para>
        </section>
        <section role="NotInToc">
            <title>Detailed Information</title>
            <para></para>
        </section>
    </section>
</chapter>