mirror of
https://github.com/systemd/systemd
synced 2024-07-22 10:44:58 +00:00
357376d0bb
If KERNEL_INSTALL_MACHINE_ID is defined in /etc/machine-info, prefer it over the machine ID from /etc/machine-id. If a machine ID is defined in neither /etc/machine-info nor in /etc/machine-id, generate a new UUID and try to write it to /etc/machine-info as KERNEL_INSTALL_MACHINE_ID and use it as the machine ID if writing it to /etc/machine-info succeeds. In practice, this means we have a more robust fallback if there's no machine ID in /etc/machine-id than just using "Default" and allows image builders to force kernel-install to use KERNEL_INSTALL_MACHINE_ID by simply writing it to /etc/machine-info themselves.
269 lines
14 KiB
XML
269 lines
14 KiB
XML
<?xml version='1.0'?>
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
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<refentry id="kernel-install"
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xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>kernel-install</title>
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<productname>systemd</productname>
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</refentryinfo>
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<refmeta>
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<refentrytitle>kernel-install</refentrytitle>
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<manvolnum>8</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>kernel-install</refname>
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<refpurpose>Add and remove kernel and initramfs images to and from /boot</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<cmdsynopsis>
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<command>kernel-install</command>
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<arg choice="plain">COMMAND</arg>
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<arg choice="opt" rep="repeat">OPTIONS</arg>
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<arg choice="plain"><replaceable>KERNEL-VERSION</replaceable></arg>
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<arg choice="plain"><replaceable>KERNEL-IMAGE</replaceable></arg>
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<arg choice="opt" rep="repeat"><replaceable>INITRD-FILE</replaceable></arg>
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</cmdsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><command>kernel-install</command> is used to install and remove kernel and initramfs images to and
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from the boot loader partition, referred to as <varname>$BOOT</varname> here. It will usually be one of
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<filename>/boot/</filename>, <filename>/efi/</filename>, or <filename>/boot/efi/</filename>, see below.
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</para>
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<para><command>kernel-install</command> will execute the files
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located in the directory <filename>/usr/lib/kernel/install.d/</filename>
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and the local administration directory <filename>/etc/kernel/install.d/</filename>.
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All files are collectively sorted and executed in lexical order, regardless of the directory in
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which they live. However, files with identical filenames replace each other.
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Files in <filename>/etc/kernel/install.d/</filename> take precedence over files with the same name
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in <filename>/usr/lib/kernel/install.d/</filename>. This can be used to override a system-supplied
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executables with a local file if needed; a symbolic link in <filename>/etc/kernel/install.d/</filename>
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with the same name as an executable in <filename>/usr/lib/kernel/install.d/</filename>,
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pointing to <filename>/dev/null</filename>, disables the executable entirely. Executables must have the
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extension <literal>.install</literal>; other extensions are ignored.</para>
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<para>An executable should return <constant>0</constant> on success. It may also
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return <constant>77</constant> to cause the whole operation to terminate
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(executables later in lexical order will be skipped).</para>
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</refsect1>
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<refsect1>
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<title>Commands</title>
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<para>The following commands are understood:</para>
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<variablelist>
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<varlistentry>
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<term><command>add <replaceable>KERNEL-VERSION</replaceable> <replaceable>KERNEL-IMAGE</replaceable> [<replaceable>INITRD-FILE</replaceable> ...]</command></term>
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<listitem>
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<para>This command expects a kernel version string and a path to a kernel image file as
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arguments. <command>kernel-install</command> calls the executables from
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<filename>/usr/lib/kernel/install.d/*.install</filename> and
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<filename>/etc/kernel/install.d/*.install</filename> with the following arguments:
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<programlisting>add <replaceable>KERNEL-VERSION</replaceable> <filename>$BOOT/<replaceable>MACHINE-ID</replaceable>/<replaceable>KERNEL-VERSION</replaceable>/</filename> <replaceable>KERNEL-IMAGE</replaceable> [<replaceable>INITRD-FILE</replaceable> ...]</programlisting>
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</para>
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<para>Three default plugins execute the following operations in this case:</para>
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<itemizedlist>
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<listitem><para><filename>00-entry-directory.install</filename> creates the directory
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<filename>$BOOT/<replaceable>MACHINE-ID</replaceable>/<replaceable>KERNEL-VERSION</replaceable>/</filename>
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if <filename>$BOOT/<replaceable>MACHINE-ID</replaceable>/</filename> already exists.
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</para></listitem>
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<listitem><para><filename>50-depmod.install</filename> runs
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<citerefentry project='man-pages'><refentrytitle>depmod</refentrytitle><manvolnum>8</manvolnum></citerefentry> for the
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<replaceable>KERNEL-VERSION</replaceable>.</para></listitem>
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<listitem><para><filename>90-loaderentry.install</filename> copies <replaceable>KERNEL-IMAGE</replaceable>
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to
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<filename>$BOOT/<replaceable>MACHINE-ID</replaceable>/<replaceable>KERNEL-VERSION</replaceable>/linux</filename>.
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If an <replaceable>INITRD-FILE</replaceable> is provided, it also copies <replaceable>INITRD-FILE</replaceable>
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to
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<filename>$BOOT/<replaceable>MACHINE-ID</replaceable>/<replaceable>KERNEL_VERSION</replaceable>/<replaceable>INITRD-FILE</replaceable></filename>.
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It also creates a boot loader entry according to the <ulink
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url="https://systemd.io/BOOT_LOADER_SPECIFICATION">Boot Loader Specification</ulink> in
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<filename>$BOOT/loader/entries/<replaceable>MACHINE-ID</replaceable>-<replaceable>KERNEL-VERSION</replaceable>.conf</filename>.
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The title of the entry is the <replaceable>PRETTY_NAME</replaceable> parameter specified in
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<filename>/etc/os-release</filename> or <filename>/usr/lib/os-release</filename> (if the former is
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missing), or "Linux <replaceable>KERNEL-VERSION</replaceable>", if unset.</para>
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<para>If the entry directory
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<filename>$BOOT/<replaceable>MACHINE-ID</replaceable>/<replaceable>KERNEL-VERSION</replaceable>/</filename>
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does not exist, this plugin does nothing.</para></listitem>
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</itemizedlist>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><command>remove <replaceable>KERNEL-VERSION</replaceable></command></term>
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<listitem>
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<para>This command expects a kernel version string as single argument. This calls executables from
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<filename>/usr/lib/kernel/install.d/*.install</filename> and
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<filename>/etc/kernel/install.d/*.install</filename> with the following arguments:
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<programlisting>remove <replaceable>KERNEL-VERSION</replaceable> <filename>$BOOT/<replaceable>MACHINE-ID</replaceable>/<replaceable>KERNEL-VERSION</replaceable>/</filename></programlisting>
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</para>
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<para>Afterwards, <command>kernel-install</command> removes the directory
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<filename>$BOOT/<replaceable>MACHINE-ID</replaceable>/<replaceable>KERNEL-VERSION</replaceable>/</filename>
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and its contents.</para>
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<para>Two default plugins execute the following operations in this case:</para>
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<itemizedlist>
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<listitem><para><filename>50-depmod.install</filename> removes the files generated by <command>depmod</command> for this kernel again.</para></listitem>
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<listitem><para><filename>90-loaderentry.install</filename> removes the file
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<filename>$BOOT/loader/entries/<replaceable>MACHINE-ID</replaceable>-<replaceable>KERNEL-VERSION</replaceable>.conf</filename>.</para></listitem>
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</itemizedlist>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>The <varname>$BOOT</varname> partition</title>
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<para>The partition where the kernels and <ulink url="https://systemd.io/BOOT_LOADER_SPECIFICATION">Boot
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Loader Specification</ulink> snippets are located is called <varname>$BOOT</varname>.
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<command>kernel-install</command> determines the location of this partition by checking
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<filename>/efi/</filename>, <filename>/boot/</filename>, and <filename>/boot/efi/</filename>
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in turn. The first location where <filename>$BOOT/loader/entries/</filename> or
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<filename>$BOOT/$MACHINE_ID/</filename> exists is used.</para>
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</refsect1>
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<refsect1>
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<title>Options</title>
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<para>The following options are understood:</para>
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<variablelist>
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<varlistentry>
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<term><option>-v</option></term>
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<term><option>--verbose</option></term>
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<listitem>
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<para>Output additional information about operations being performed.</para>
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</listitem>
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</varlistentry>
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<xi:include href="standard-options.xml" xpointer="help" />
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Environment variables</title>
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<para>If <option>--verbose</option> is used, <varname>$KERNEL_INSTALL_VERBOSE=1</varname> will be set for
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the plugins. They may output additional logs in this case.</para>
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<para>If <varname>MACHINE_ID=</varname> is set and not empty, it will be used as <replaceable>MACHINE-ID</replaceable>,
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overriding any automatic detection attempts. The value must be a valid machine ID (32 hexadecimal characters).</para>
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<para><varname>KERNEL_INSTALL_MACHINE_ID=</varname> is set for the plugins to the desired <replaceable>MACHINE-ID</replaceable> –
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either 32 hexadecimal characters or the special value <literal>Default</literal>.</para>
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<para><varname>KERNEL_INSTALL_BOOT_ROOT=</varname> is set for the plugins to the root directory (mount point, usually) of the hierarchy
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where boot-loader entries, kernel images, and associated resources should be placed. Can be overridden by setting <varname>BOOT_ROOT=</varname>.</para>
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</refsect1>
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<refsect1>
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<title>Exit status</title>
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<para>If every executable returns 0 or 77, 0 is returned, and a non-zero failure code otherwise.</para>
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</refsect1>
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<refsect1>
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<title>Files</title>
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<variablelist>
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<varlistentry>
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<term>
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<filename>/usr/lib/kernel/install.d/*.install</filename>
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<filename>/etc/kernel/install.d/*.install</filename>
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</term>
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<listitem>
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<para>Drop-in files which are executed by kernel-install.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<filename>/usr/lib/kernel/cmdline</filename>
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<filename>/etc/kernel/cmdline</filename>
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<filename>/proc/cmdline</filename>
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</term>
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<listitem>
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<para>Read by <filename>90-loaderentry.install</filename>. The content of the file
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<filename>/etc/kernel/cmdline</filename> specifies the kernel command line to use. If that file does not
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exist, <filename>/usr/lib/kernel/cmdline</filename> is used. If that also does not exist,
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<filename>/proc/cmdline</filename> is used.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<filename>/etc/kernel/tries</filename>
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</term>
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<listitem>
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<para>Read by <filename>90-loaderentry.install</filename>. If this file exists a numeric value is read from
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it and the naming of the generated entry file is slightly altered to include it as
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<filename>$BOOT/loader/entries/<replaceable>MACHINE-ID</replaceable>-<replaceable>KERNEL-VERSION</replaceable>+<replaceable>TRIES</replaceable>.conf</filename>. This
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is useful for boot loaders such as
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<citerefentry><refentrytitle>systemd-boot</refentrytitle><manvolnum>7</manvolnum></citerefentry> which
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implement boot attempt counting with a counter embedded in the entry file name.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<filename>/etc/machine-id</filename>
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</term>
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<listitem>
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<para>The content of this file specifies the machine identification
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<replaceable>MACHINE-ID</replaceable>. If <filename>/etc/machine-id</filename>
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cannot be read or is temporary (backed by a file on <constant>tmpfs</constant>),
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<command>kernel-install</command> will use <literal>Default</literal> instead.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<filename>/etc/machine-info</filename>
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</term>
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<listitem>
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<para>If this file contains the <varname>KERNEL_INSTALL_MACHINE_ID</varname> variable,
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<command>kernel-install</command> will use it as <replaceable>MACHINE-ID</replaceable> instead of
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the contents of <filename>/etc/machine-id</filename>. If the variable is not found in
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<filename>/etc/machine-info</filename>, <command>kernel-install</command> will try to save the
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machine ID it uses to install to <varname>$BOOT</varname> to this file.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<filename>/etc/os-release</filename>
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<filename>/usr/lib/os-release</filename>
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</term>
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<listitem>
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<para>Read by <filename>90-loaderentry.install</filename>.
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If available, <varname>PRETTY_NAME</varname> is read from these files and used as the title of the boot menu entry.
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Otherwise, <literal>Linux <replaceable>KERNEL-VERSION</replaceable></literal> will be used.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>os-release</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry project='man-pages'><refentrytitle>depmod</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd-boot</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
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<ulink url="https://systemd.io/BOOT_LOADER_SPECIFICATION">Boot Loader Specification</ulink>
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</para>
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</refsect1>
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</refentry>
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