initramfs-tools
TLDR
Update initramfs for current kernel
$ sudo update-initramfs -u
Create new initramfs$ sudo update-initramfs -c -k [$(uname -r)]
Update all initramfs images$ sudo update-initramfs -u -k all
Delete initramfs for kernel$ sudo update-initramfs -d -k [5.10.0-1]
Show verbose output$ sudo update-initramfs -u -v
SYNOPSIS
update-initramfs [options]
DESCRIPTION
initramfs-tools manages the initial RAM filesystem (initramfs) on Debian-based systems. The initramfs contains the minimal filesystem loaded before the real root filesystem is mounted.
It includes drivers, scripts, and tools needed for early boot, such as filesystem drivers, LVM, RAID, or encryption setup.
PARAMETERS
-c
Create new initramfs.-u
Update existing initramfs.-d
Delete initramfs.-k version
Kernel version (or "all").-v
Verbose output.-b directory
Set boot directory.
CONFIGURATION
$ /etc/initramfs-tools/initramfs.conf Main config
/etc/initramfs-tools/modules Modules to include
/etc/initramfs-tools/hooks/ Hook scripts
/etc/initramfs-tools/scripts/ Boot scripts
/etc/initramfs-tools/modules Modules to include
/etc/initramfs-tools/hooks/ Hook scripts
/etc/initramfs-tools/scripts/ Boot scripts
CAVEATS
Debian/Ubuntu specific. Incorrect configuration may prevent boot. Always keep a working backup. Custom modules need manual configuration.
HISTORY
initramfs-tools replaced the older initrd mechanism on Debian. It provides a modular, scriptable framework for building the initial filesystem, developed by the Debian project.
SEE ALSO
mkinitramfs(8), initramfs.conf(5), dracut(8)
