2 <!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.2//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
6 SPDX-License-Identifier: LGPL-2.1+
9 <refentry id=
"kernel-install">
12 <title>kernel-install
</title>
13 <productname>systemd
</productname>
17 <refentrytitle>kernel-install
</refentrytitle>
18 <manvolnum>8</manvolnum>
22 <refname>kernel-install
</refname>
23 <refpurpose>Add and remove kernel and initramfs images to and from /boot
</refpurpose>
28 <command>kernel-install
</command>
29 <arg choice=
"plain">COMMAND
</arg>
30 <arg choice=
"plain"><replaceable>KERNEL-VERSION
</replaceable></arg>
31 <arg choice=
"opt"><replaceable>KERNEL-IMAGE
</replaceable></arg>
36 <title>Description
</title>
38 <command>kernel-install
</command> is used to install and remove kernel and
39 initramfs images to and from
<filename>/boot
</filename>.
42 <para><command>kernel-install
</command> will execute the files
43 located in the directory
<filename>/usr/lib/kernel/install.d/
</filename>
44 and the local administration directory
<filename>/etc/kernel/install.d/
</filename>.
45 All files are collectively sorted and executed in lexical order, regardless of the directory in
46 which they live. However, files with identical filenames replace each other.
47 Files in
<filename>/etc/kernel/install.d/
</filename> take precedence over files with the same name
48 in
<filename>/usr/lib/kernel/install.d/
</filename>. This can be used to override a system-supplied
49 executables with a local file if needed; a symbolic link in
<filename>/etc/kernel/install.d/
</filename>
50 with the same name as an executable in
<filename>/usr/lib/kernel/install.d/
</filename>,
51 pointing to
<filename>/dev/null
</filename>, disables the executable entirely. Executables must have the
52 extension
<literal>.install
</literal>; other extensions are ignored.
</para>
54 <para>An executable should return
<constant>0</constant> on success. It may also
55 return
<constant>77</constant> to cause the whole operation to terminate
56 (executables later in lexical order will be skipped).
</para>
60 <title>Commands
</title>
61 <para>The following commands are understood:
</para>
64 <term><command>add
<replaceable>KERNEL-VERSION
</replaceable> <replaceable>KERNEL-IMAGE
</replaceable></command></term>
66 <para>This command expects a kernel version string and a path to a kernel image file as
67 arguments.
<command>kernel-install
</command> creates the directory
68 <filename>/boot/
<replaceable>MACHINE-ID
</replaceable>/
<replaceable>KERNEL-VERSION
</replaceable>/
</filename>
69 and calls the executables from
<filename>/usr/lib/kernel/install.d/*.install
</filename> and
70 <filename>/etc/kernel/install.d/*.install
</filename> with the following arguments:
72 <programlisting>add
<replaceable>KERNEL-VERSION
</replaceable> <filename>/boot/
<replaceable>MACHINE-ID
</replaceable>/
<replaceable>KERNEL-VERSION
</replaceable>/
</filename> <replaceable>KERNEL-IMAGE
</replaceable></programlisting>
75 <para>Two default plugins execute the following operations in this case:
</para>
79 <listitem><para><filename>50-depmod.install
</filename> runs
80 <citerefentry><refentrytitle>depmod
</refentrytitle><manvolnum>8</manvolnum></citerefentry> for the
81 <replaceable>KERNEL-VERSION
</replaceable>.
</para></listitem>
83 <listitem><para><filename>90-loaderentry.install
</filename> copies
<replaceable>KERNEL-IMAGE
</replaceable>
85 <filename>/boot/
<replaceable>MACHINE-ID
</replaceable>/
<replaceable>KERNEL-VERSION
</replaceable>/linux
</filename>.
86 It also creates a boot loader entry according to the
<ulink
87 url=
"https://systemd.io/BOOT_LOADER_SPECIFICATION">Boot Loader Specification
</ulink> in
88 <filename>/boot/loader/entries/
<replaceable>MACHINE-ID
</replaceable>-
<replaceable>KERNEL-VERSION
</replaceable>.conf
</filename>.
89 The title of the entry is the
<replaceable>PRETTY_NAME
</replaceable> parameter specified in
90 <filename>/etc/os-release
</filename> or
<filename>/usr/lib/os-release
</filename> (if the former is
91 missing), or
"Linux <replaceable>KERNEL-VERSION</replaceable>", if unset. If the file
92 <filename>initrd
</filename> is found next to the kernel image file, the initrd will be added to the
93 configuration.
</para></listitem>
98 <term><command>remove
<replaceable>KERNEL-VERSION
</replaceable></command></term>
100 <para>This command expects a kernel version string as single argument. This calls executables from
101 <filename>/usr/lib/kernel/install.d/*.install
</filename> and
102 <filename>/etc/kernel/install.d/*.install
</filename> with the following arguments:
104 <programlisting>remove
<replaceable>KERNEL-VERSION
</replaceable> <filename>/boot/
<replaceable>MACHINE-ID
</replaceable>/
<replaceable>KERNEL-VERSION
</replaceable>/
</filename></programlisting>
107 <para>Afterwards,
<command>kernel-install
</command> removes the directory
108 <filename>/boot/
<replaceable>MACHINE-ID
</replaceable>/
<replaceable>KERNEL-VERSION
</replaceable>/
</filename>
109 and its contents.
</para>
111 <para>Two default plugins execute the following operations in this case:
</para>
115 <listitem><para><filename>50-depmod.install
</filename> removes the files generated by
<command>depmod
</command> for this kernel again.
</para></listitem>
117 <listitem><para><filename>90-loaderentry.install
</filename> removes the file
118 <filename>/boot/loader/entries/
<replaceable>MACHINE-ID
</replaceable>-
<replaceable>KERNEL-VERSION
</replaceable>.conf
</filename>.
</para></listitem>
129 <title>Exit status
</title>
130 <para>If every executable returns
0 or
77,
0 is returned, and a non-zero failure code otherwise.
</para>
138 <filename>/usr/lib/kernel/install.d/*.install
</filename>
139 <filename>/etc/kernel/install.d/*.install
</filename>
142 <para>Drop-in files which are executed by kernel-install.
</para>
147 <filename>/etc/kernel/cmdline
</filename>
148 <filename>/proc/cmdline
</filename>
151 <para>Read by
<filename>90-loaderentry.install
</filename>. The content of the file
152 <filename>/etc/kernel/cmdline
</filename> specifies the kernel command line to use. If that file does not
153 exist,
<filename>/proc/cmdline
</filename> is used.
</para>
158 <filename>/etc/kernel/tries
</filename>
161 <para>Read by
<filename>90-loaderentry.install
</filename>. If this file exists a numeric value is read from
162 it and the naming of the generated entry file is slightly altered to include it as
163 <filename>/boot/loader/entries/
<replaceable>MACHINE-ID
</replaceable>-
<replaceable>KERNEL-VERSION
</replaceable>+
<replaceable>TRIES
</replaceable>.conf
</filename>. This
164 is useful for boot loaders such as
165 <citerefentry><refentrytitle>systemd-boot
</refentrytitle><manvolnum>7</manvolnum></citerefentry> which
166 implement boot attempt counting with a counter embedded in the entry file name.
</para>
171 <filename>/etc/machine-id
</filename>
174 <para>The content of the file specifies the machine identification
<replaceable>MACHINE-ID
</replaceable>.
</para>
179 <filename>/etc/os-release
</filename>
180 <filename>/usr/lib/os-release
</filename>
183 <para>The content of the file specifies the operating system title
<replaceable>PRETTY_NAME
</replaceable>.
</para>
190 <title>See Also
</title>
192 <citerefentry><refentrytitle>machine-id
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
193 <citerefentry><refentrytitle>os-release
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
194 <citerefentry><refentrytitle>depmod
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
195 <citerefentry><refentrytitle>systemd-boot
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
196 <ulink url=
"https://systemd.io/BOOT_LOADER_SPECIFICATION">Boot Loader Specification
</ulink>