update-initramfs -c|-d|-u [-k version] [-t] [-v] [-b directory] [-h]
The update-initramfs script manages your initramfs images on your local box. It keeps track of the existing initramfs archives in /boot. There are three modes of operation create, update or delete. You must at least specify one of those modes.
The initramfs is a gzipped cpio archive. At boot time, the kernel unpacks that archive into RAM disk, mounts and uses it as initial root file system. All finding of the root device happens in this early userspace.
The use of "all" for the version string specifies update-initramfs to execute the chosen action for all kernel versions, that are already known to update-initramfs.
Update the initramfs of the newest kernel:
Create the initramfs for a specific kernel:
update-initramfs -c -k 2.6.18-1-686
The initramfs-tools are written by Maximilian Attems <email@example.com>, Jeff Bailey <firstname.lastname@example.org> and numerous others.
initramfs.conf(5), initramfs-tools(8), mkinitramfs(8), lsinitramfs(8).