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 <filename>/etc/conf.d/bootmisc</filename> file defines the following configuration variables:</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 <filename>/etc/conf.d/fsck</filename> file defines the following configuration variables:</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/modules</filename>: Kernel module configuration</title>
        <section role="NotInToc">
            <title>Purpose</title>
            <para>The <filename>/etc/conf.d/modules</filename> file specifies additional kernel modules to load during system initialisation.</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 <filename>/etc/conf.d/modules</filename> file allows you to specify additional kernel modules for the system to load during initialisation.  This is typically unnecessary as the <package>eudev</package> system will automatically load any modules required for the correct functioning of your hardware.  However, some advanced use cases may require the loading of additional kernel modules.</para>
            <para>The <filename>/etc/conf.d/modules</filename> file defines the <varname>modules</varname> configuration variables.  This is a space-delimited list of modules to load.</para>
            <para>For each module specified, an additional variable, <varname>module_<replaceable>MODNAME</replaceable>_args</varname>, is defined, where <replaceable>MODNAME</replaceable> is the name of the module.  The <varname>module_<replaceable>MODNAME</replaceable>_args</varname> variable controls the arguments passed to the module.  Refer to the documentation for each module for a list of arguments it supports.</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/urandom</filename>: Random number configuration</title>
        <section role="NotInToc">
            <title>Purpose</title>
            <para>The <filename>/etc/conf.d/urandom</filename> file determines the path where the random number seed is stored when the system is shut down.</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 <filename>/etc/conf.d/urandom</filename> file defines a single configuration variable, <varname>urandom_seed</varname>, which specifies the path in which to save the random number seed when the system is shut down.  The default is <filename>/var/lib/misc/random-seed</filename>.  This variable must point to a path that is on the root filesystem; if <filename class="directory">/var</filename> is a separate filesystem, you must configure this variable to use a different path.</para>
        </section>
    </section>
    <section>
        <title><filename>/etc/default/console-setup</filename>: Virtual terminal configuration</title>
        <section role="NotInToc">
            <title>Purpose</title>
            <para>The <filename>/etc/default/console-setup</filename> file determines the configuration of the system virtual terminals or consoles.  Note that this does not include graphical terminals run inside X11 (such as Konsole or XFCE Terminal).</para>
        </section>
        <section role="NotInToc">
            <title>Syntax</title>
            <para>Shell script style.  Variables are in uppercase.</para>
        </section>
        <section role="NotInToc">
            <title>External References</title>
            <para>For more information, consult the official manual page for console-setup(5).  This manual page is available in the <package>console-setup-doc</package> package.  If your computer has an Internet connection, you may also read it <ulink url="https://manpages.debian.org/stable/console-setup/console-setup.5.en.html">on the Web</ulink>.</para>
        </section>
    </section>
    <section>
        <title><filename>/etc/default/keyboard</filename>: Console keyboard configuration</title>
        <section role="NotInToc">
            <title>Purpose</title>
            <para>The <filename>/etc/default/keyboard</filename> file determines the configuration of the keyboard on the system virtual terminals or consoles.  This file does not control the configuration of the keyboard inside X11 or a desktop environment (such as KDE or LXQt).</para>
        </section>
        <section role="NotInToc">
            <title>Syntax</title>
            <para>Shell script style.  Variables are in uppercase.</para>
        </section>
        <section role="NotInToc">
            <title>Detailed Information</title>
            <para>The <filename>/etc/default/keyboard</filename> file is used by the <package>console-setup</package> package (when the <literal>console-setup</literal> service is enabled) to configure the keyboard model and layout in use on the system's virtual terminals.  The most important variables in the <filename>/etc/default/keyboard</filename> file are the <varname>XKBMODEL</varname> variable, which controls the model of keyboard, and the <varname>XKBLAYOUT</varname> variable, which controls the layout of the keyboard.</para>
            <para>In order to use additional keyboard layouts, you must install the <package>console-keymaps</package> package.</para>
        </section>
        <section role="NotInToc">
            <title>External Resources</title>
            <para>For more information, consult the official manual page for keyboard(5).  This manual page is available in the <package>console-setup-doc</package> package.  If your computer has an Internet connection, you may also read it <ulink url="https://manpages.debian.org/stable/console-setup/keyboard.5.en.html">on the Web</ulink>.</para>
        </section>
    </section>
    <section>
        <title><filename class="directory">/etc/dracut.conf.d/</filename>: Early system initialisation configuration</title>
        <section role="NotInToc">
            <title>Purpose</title>
            <para>The <filename class="directory">/etc/dracut.conf.d</filename> directory contains files that determine the configuration of <package>dracut</package>, the initial RAM disk generation system for the Adélie Linux system.  The initial RAM disk is needed on some computers during system initialisation; tasks it may perform include enabling access to a disk, unlocking an encrypted partition, or establishing a network connection.</para>
        </section>
        <section role="NotInToc">
            <title>Syntax</title>
            <para>Shell script style.  Variables are in lowercase.</para>
        </section>
        <section role="NotInToc">
            <title>External Resources</title>
            <para>For more information, consult the dracut.conf(5) manual page.  This manual page is available in the <package>dracut-doc</package> package.</para>
        </section>
    </section>
    <section>
        <title><filename>/etc/fstab</filename>: Filesystem mount point configuration</title>
        <section role="NotInToc">
            <title>Purpose</title>
            <para>The <filename>/etc/fstab</filename> file determines the mount points of file systems on the hard disk(s) connected to a system.  It may also control whether or not users may mount removable storage devices such as CD-ROM devices, and where they may mount them.</para>
        </section>
        <section role="NotInToc">
            <title>Syntax</title>
            <para>The syntax for <filename>/etc/fstab</filename> is columnar in nature.  There may be any amount of whitespace between columns; the following two lines will be viewed identically to the system:</para>
            <informalexample>
<programlisting>
/dev/sda1 /boot ext3 defaults 0 1
/dev/sda1       /boot       ext3        defaults    0   1
</programlisting>
            </informalexample>
        </section>
        <section role="NotInToc">
            <title>External Resources</title>
            <para>For more information, consult the fstab(5) manual page.  This manual page is available in the <package>util-linux-doc</package> package.</para>
        </section>
    </section>
    <section>
        <title><filename>/etc/hostname</filename>: Host name configuration</title>
        <section role="NotInToc">
            <title>Purpose</title>
            <para>The <filename>/etc/hostname</filename> file determines the host name of the system.  This is used in system prompts, and for identification on a network.</para>
        </section>
        <section role="NotInToc">
            <title>Syntax</title>
            <para>The host name must appear as the only content of this file.  Any other contents are invalid.</para>
        </section>
        <section role="NotInToc">
            <title>Detailed Information</title>
            <para>The <filename>/etc/hostname</filename> is read during system initialisation.  The system host name is set to the contents of this file.  If the <filename>/etc/hostname</filename> file is missing or corrupt, the system will retain the kernel's default host name &mdash; with the default Adélie Linux kernel, this is "<literal>adelie</literal>".</para>
        </section>
    </section>
    <section>
        <title><filename>/etc/inputrc</filename>: Bash shell keyboard configuration</title>
        <section role="NotInToc">
            <title>Purpose</title>
            <para>The <filename>/etc/inputrc</filename> file determines the behaviour of keyboard input and the system bell in programs that use the GNU readline library.  The GNU readline library is not packaged for the Adélie Linux system; therefore, the only system packages that would use the configuration in this file are <package>bash</package> and <package>gdb</package>, which contain their own private copies of the GNU readline library.</para>
        </section>
        <section role="NotInToc">
            <title>Syntax</title>
            <para>The <filename>/etc/inputrc</filename> is declarative in nature; variables are set using the <command>set</command> command, and escape sequences are mapped to functions using the format: <literal>"<replaceable>&lt;escape sequence&gt;</replaceable>": <replaceable>function</replaceable></literal>.</para>
        </section>
        <section role="NotInToc">
            <title>External Resources</title>
            <para>There are a few comments in the <filename>/etc/inputrc</filename> file.  Since the GNU readline library is not packaged for the Adélie Linux system, it is not possible to read the manual page.</para>
        </section>
    </section>
</chapter>