The /etc/kernel/postinst.d directory is used for storing scripts that are executed after the installation of a new Linux kernel image. These scripts are typically part of the package management system and are executed as part of the post-installation process when a new kernel is installed or updated on a Debian-based Linux system.

Here's how it works:

    When a new kernel package is installed or updated on a Debian-based system (e.g., Ubuntu), a set of scripts, including those in /etc/kernel/postinst.d, are executed automatically. These scripts handle tasks related to configuring the system for the new kernel.

    Each script in the /etc/kernel/postinst.d directory is responsible for a specific task, such as updating bootloader configurations, creating kernel modules, or handling other necessary configurations.

    These scripts are executed with specific arguments and in a specific order. Typically, they receive arguments like the kernel version and image path, allowing them to perform actions related to the installed kernel.

    These post-installation scripts ensure that the new kernel is properly integrated into the system, that boot configurations are updated, and that any necessary modules are built or loaded.

By organizing these scripts into the /etc/kernel/postinst.d directory, the package management system makes it easy to add or modify post-installation steps when dealing with kernel updates. This helps maintain system integrity and ensures that the new kernel functions correctly in the context of the specific system configuration.

he scripts in the /etc/kernel/postinst.d directory are typically executed in alphanumeric order, which is based on the names of the script files. The order is determined by sorting the filenames lexicographically. In your directory listing, the order in which these scripts will be executed is as follows:

    dkms (Executed first)
    initramfs-tools
    unattended-upgrades
    update-notifier
    xx-initramfs-cleanup
    xx-update-initrd-links (Executed last)

So, based on the filenames, the scripts will be executed in the order shown above. If you need to control the order in which these scripts run, you can rename them to change their lexicographical order or add numeric prefixes to the filenames. Scripts with lower numeric prefixes will be executed before those with higher numeric prefixes.