kernel-install — Add and remove kernel and initramfs images to and from /boot
kernel-install COMMAND [Options...] KERNEL-VERSION KERNEL-IMAGE [INITRD-FILE...]
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).
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 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.
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 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.
The following options are understood:
- -v, --verbose
Output additional information about operations being performed.
- -h, --help
Print a short help text and exit.
If --verbose is used, $KERNEL_INSTALL_VERBOSE=1 will be set for the plugins. They may output additional logs in this case.
If every executable returns 0 or 77, 0 is returned, and a non-zero failure code otherwise.
- /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.
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.
The content of the file specifies the machine identification MACHINE-ID.
- /etc/os-release /usr/lib/os-release
The content of the file specifies the operating system title PRETTY_NAME.
machine-id(5), os-release(5), depmod(8), systemd-boot(7), Boot Loader Specification
Boot Loader Specification
systemd-boot(7), systemd.directives(7), systemd.index(7).