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