NAME

       kernel-install - Add and remove kernel and initramfs images to and from /boot

SYNOPSIS

       kernel-install COMMAND [OPTIONS...] KERNEL-VERSION KERNEL-IMAGE [INITRD-FILE...]

DESCRIPTION

       kernel-install is used to install and remove kernel and initramfs images to and from the
       boot loader partition, referred to as $BOOT here. It will usually be one of /boot/, /efi/,
       or /boot/efi/, see below.

       kernel-install will execute the files located in the directory /usr/lib/kernel/install.d/
       and the local administration directory /etc/kernel/install.d/. 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
       /etc/kernel/install.d/ take precedence over files with the same name in
       /usr/lib/kernel/install.d/. This can be used to override a system-supplied executables
       with a local file if needed; a symbolic link in /etc/kernel/install.d/ with the same name
       as an executable in /usr/lib/kernel/install.d/, pointing to /dev/null, disables the
       executable entirely. Executables must have the extension ".install"; other extensions are
       ignored.

       An executable should return 0 on success. It may also return 77 to cause the whole
       operation to terminate (executables later in lexical order will be skipped).

COMMANDS

       The following commands are understood:

       add KERNEL-VERSION KERNEL-IMAGE [INITRD-FILE ...]
           This command expects a kernel version string and a path to a kernel image file as
           arguments.  kernel-install calls the executables from
           /usr/lib/kernel/install.d/*.install and /etc/kernel/install.d/*.install with the
           following arguments:

               add KERNEL-VERSION $BOOT/MACHINE-ID/KERNEL-VERSION/ KERNEL-IMAGE [INITRD-FILE ...]

           Three default plugins execute the following operations in this case:

           •   00-entry-directory.install creates the directory $BOOT/MACHINE-ID/KERNEL-VERSION/
               if $BOOT/MACHINE-ID/ already exists.

           •   50-depmod.install runs depmod(8) for the KERNEL-VERSION.

           •   90-loaderentry.install copies KERNEL-IMAGE to
               $BOOT/MACHINE-ID/KERNEL-VERSION/linux. If an INITRD-FILE is provided, it also
               copies INITRD-FILE to $BOOT/MACHINE-ID/KERNEL_VERSION/INITRD-FILE. It also creates
               a boot loader entry according to the Boot Loader Specification[1] in
               $BOOT/loader/entries/MACHINE-ID-KERNEL-VERSION.conf. The title of the entry is the
               PRETTY_NAME parameter specified in /etc/os-release or /usr/lib/os-release (if the
               former is missing), or "Linux KERNEL-VERSION", if unset.

               If the entry directory $BOOT/MACHINE-ID/KERNEL-VERSION/ does not exist, this
               plugin does nothing.

       remove KERNEL-VERSION
           This command expects a kernel version string as single argument. This calls
           executables from /usr/lib/kernel/install.d/*.install and
           /etc/kernel/install.d/*.install with the following arguments:

               remove KERNEL-VERSION $BOOT/MACHINE-ID/KERNEL-VERSION/

           Afterwards, kernel-install removes the directory $BOOT/MACHINE-ID/KERNEL-VERSION/ and
           its contents.

           Two default plugins execute the following operations in this case:

           •   50-depmod.install removes the files generated by depmod for this kernel again.

           •   90-loaderentry.install removes the file
               $BOOT/loader/entries/MACHINE-ID-KERNEL-VERSION.conf.

THE $BOOT PARTITION

       The partition where the kernels and Boot Loader Specification[1] snippets are located is
       called $BOOT.  kernel-install determines the location of this partition by checking /efi/,
       /boot/, and /boot/efi/ in turn. The first location where $BOOT/loader/entries/ or
       $BOOT/$MACHINE_ID/ exists is used.

OPTIONS

       The following options are understood:

       -v, --verbose
           Output additional information about operations being performed.

       -h, --help
           Print a short help text and exit.

ENVIRONMENT VARIABLES

       If --verbose is used, $KERNEL_INSTALL_VERBOSE=1 will be set for the plugins. They may
       output additional logs in this case.

EXIT STATUS

       If every executable returns 0 or 77, 0 is returned, and a non-zero failure code otherwise.

FILES

       /usr/lib/kernel/install.d/*.install /etc/kernel/install.d/*.install
           Drop-in files which are executed by kernel-install.

       /etc/kernel/cmdline /proc/cmdline
           Read by 90-loaderentry.install. The content of the file /etc/kernel/cmdline specifies
           the kernel command line to use. If that file does not exist, /proc/cmdline is used.

       /etc/kernel/tries
           Read by 90-loaderentry.install. 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
           $BOOT/loader/entries/MACHINE-ID-KERNEL-VERSION+TRIES.conf. This is useful for boot
           loaders such as systemd-boot(7) which implement boot attempt counting with a counter
           embedded in the entry file name.

       /etc/machine-id
           The content of this file specifies the machine identification MACHINE-ID. If it cannot
           read /etc/machine-id, kernel-install will use "Linux" as the machine ID instead.

       /etc/os-release /usr/lib/os-release
           The content of the file specifies the operating system title PRETTY_NAME.

SEE ALSO

       machine-id(5), os-release(5), depmod(8), systemd-boot(7), Boot Loader Specification[1]

NOTES

        1. Boot Loader Specification
           https://systemd.io/BOOT_LOADER_SPECIFICATION