alt

alt

    The specific kernel version to switch to. This typically corresponds to the directory or file name representing the kernel within the `/boot` directory.

The `alt` command in Linux, often part of older systems or specialized distributions like Debian or systems that supported multiple installed kernels, provided a mechanism for switching between different installed kernels. It primarily operated by modifying symbolic links and bootloader configurations to select a specific kernel version to load upon the next system boot. This was useful for testing new kernels, reverting to stable versions after upgrades, or accommodating different hardware configurations that might require specific kernel modules. The command typically interacted with configuration files within `/boot` and `/etc` to manage available kernels and their corresponding initrd (initial ramdisk) images. While no longer as commonplace with advancements in bootloaders like GRUB (which directly provides kernel selection menus), `alt` historically offered a simpler interface for kernel management, particularly for users less comfortable with manually editing GRUB configuration files or similar bootloader setups. Its functionality has largely been superseded by more robust bootloader capabilities and distribution-specific kernel management tools, but served as a helpful way to manage Linux kernels for users who preferred command line interfaces.

The `alt` command is heavily distribution-dependent. Its availability and functionality vary. It might require root privileges to execute.

The `alt` command frequently interacted with files such as `/etc/lilo.conf`, `/boot/grub/menu.lst` or similar bootloader configuration files in order to affect change of the kernel which would be loaded.

Older versions of `alt` may lack robust error handling. Always ensure proper backups and understanding of your bootloader configuration before use.

The `alt` command was primarily utilized in older Linux distributions before GRUB2 became the dominant bootloader. Its aim was to simplify the process of switching between kernels for testing or fallback purposes. With the wider adoption of GRUB and similar bootloaders featuring built-in kernel selection menus, the necessity for dedicated tools like `alt` diminished. Therefore it is largely not in use.

update-initramfs(8), mkinitramfs(8), grub-mkconfig(8), bootctl(1)